DE102021101223A1 - More wear-resistant bicycle sprocket pairing and sprocket cassette with such - Google Patents

Abstract

The present invention relates to a bicycle rear wheel sprocket pair (11, 13, 15, 17) for meshing, force-transmitting positive engagement with a bicycle roller chain (50), the rear wheel sprocket pair (11, 13, 15, 17) being rotatable about a pinion axis (R). , wherein the pinion axis (R) defines an axial direction running along the pinion axis (R), a radial direction running orthogonally to the pinion axis (R) and a circumferential direction running around the pinion axis (R), the rear wheel pinion pair (11, 13, 15, 17) a larger sprocket (12, 14, 16, 18) and a smaller sprocket which is coaxially connected to it for joint non-slip rotation about the sprocket axis (R) and is axially immediately adjacent to the larger sprocket (12, 14, 16, 18). (10, 12, 14, 16), wherein the larger sprocket (12, 14, 16, 18) has an even number of teeth equal to or less than 22 teeth and wherein the difference in the number of teeth between the larger and the smaller sprocket (10, 12, 14, 16) gen au is two teeth.

Description

The present invention relates to a bicycle rear wheel sprocket pairing for meshing, force-transmitting positive engagement with a bicycle roller chain. The pair of rear wheel pinions can be rotated about a pinion axis, with the pinion axis defining an axial direction running along the pinion axis, a radial direction running orthogonally to the pinion axis and a circumferential direction running around the pinion axis, with the pair of rear wheel pinions having a larger pinion and one with it for common non-slip rotation which comprises a smaller pinion coaxially connected to the pinion axis and immediately adjacent axially to the larger pinion.

From the EP 1 188 658 B1 a rear wheel sprocket cassette is known which comprises seven sprockets. The tooth gradation of the sprocket from the smallest, outermost sprocket to the largest, innermost sprocket is 11 - 13 - 15 - 17 - 21 - 25 - 29 - 33. The known sprocket cassette therefore only has sprockets with an odd number of teeth. The outermost sprocket is the sprocket furthest away from the longitudinal center plane of a bicycle, which is orthogonal to the sprocket axis, of a bicycle carrying the sprocket cassette. Accordingly, the innermost sprocket is the sprocket closest to the longitudinal center plane of the bicycle.

Bicycle roller chains circulating in meshing engagement around the rear wheel sprocket are also known, having a plurality of chain rollers spaced apart from one another in the chain longitudinal direction by a predetermined chain pitch and link plates connecting the chain rollers. The chain links of the well-known and conventional bicycle roller chains are formed by pairs of plates, with inner plate pairs and outer plate pairs alternating in the longitudinal direction of the chain, which is also a chain direction because of the closed circulating design of a bicycle roller chain. End areas of pairs of outer plates overlap end areas of pairs of inner plates in a manner known per se, so that the end areas of a pair of inner plates are arranged between an end area of a pair of outer plates and the chain roller held between this end area, namely one inner plate end area on each of the two end faces of the chain roller. The clear width to be measured in the chain width direction, i.e. parallel to the roller axes of the chain rollers, is therefore smaller between two inner plates of a pair of inner plates than the clear width between two outer plates of a pair of outer plates. The clear width of a pair of link plates defines the engagement space available for engagement of a tooth of a pinion with the roller chain. Consequently, narrow chain links defined by pairs of inner link plates and wide chain links defined by pairs of outer link plates alternately follow one another on the roller chain as chain link types. Due to the alternating inner and outer link chain links in the direction of chain rotation, a bicycle roller chain always has an even number of chain links. The bicycle roller chain is also simply referred to below as a "bicycle chain" or "chain".

For the sake of simplicity, pinions with an odd number of teeth are also referred to below as "odd-numbered pinions" and accordingly pinions with an even number of teeth are referred to as "even-numbered pinions".

The disadvantage of odd-numbered sprockets is that the engagement assignment of one and the same tooth to a chain link type changes with each cycle of the bicycle chain. Thus, one and the same tooth alternately engages a narrow inner-plate link and a wide outer-plate link on successive revolutions of the bicycle chain. Each tooth of an odd-numbered sprocket must therefore be designed in such a way that it can engage in a narrow chain link.

A physical weakening of the sprocket can result from the shifting conditions that must be met in order to shift the bicycle chain from the sprocket to the next smaller sprocket. As is well known, this shifting is done on the rear wheel cassette by a derailleur, whose chain guide roller, which guides the bicycle chain in a deflecting manner, is coplanar with the rider of a bicycle using appropriate power transmission mechanisms, such as mechanically using a cable pull or an electric motor using a "shift-by-wire" system with the sprocket that takes over the chain after the shifting process. The chain is thus shifted from the currently chain-guiding sprocket to the future chain-guiding sprocket.

On the front side of the sprockets, which points to the next smaller sprocket, there are depression formations in the form of flat depressions in the front side, into which plates, usually outer plates, of the bicycle chain can dip at least in sections in order to be able to bring the chain axially close to the larger sprocket and thus support the switching process. There are upshift indentations that assist in shifting the chain from the larger sprocket to the next smaller sprocket for an upshift, and there are downshift indentations that assist in shifting the chain from the adjacent small sprocket to the larger sprocket for a downshift. The depression formations follow in their shape and/or their radially inner boundary - When viewed axially from the outside of a pair of sprockets consisting of a larger and an adjacent smaller sprocket, i.e. with the smaller sprocket located closer to the viewer - the course of the bicycle chain in the transition area between the smaller and the larger sprocket during the associated switching process. That is, the upshift indentation or/and a radially inner edge thereof roughly approaches the smaller sprocket radially from a radially more outward location on the larger sprocket progressing counterclockwise, and the downshift indentation or/and a radially inner edge thereof roughly approaches the smaller sprocket radially from a more radially outward location on the larger sprocket as it progresses clockwise.

Usually, sprockets have teeth designed as release teeth, which when shifting up to the next smaller sprocket are the last to engage between pairs of link plates of a chain link, before the chain leaves the larger sprocket for the smaller sprocket. In the usual driving directions of rotation of rear wheel sprockets, i.e. clockwise from the outside when viewed along the sprocket axis as a reference, an output tooth is usually clockwise adjacent to its associated upshift indentation formation, so that the chain engages with the output tooth laterally on the counterclockwise on the Delivery tooth can move past the following teeth using the upshift recess formation as a movement space radially inwards.

Likewise, for downshifts, fangs are formed on the larger sprocket, which are intended to engage as the first teeth with the bicycle chain to be shifted onto the larger sprocket. Here, the bicycle chain is axially brought closer to the larger sprocket using the downshift indentation formation as movement space, so that the chain first moves past the clockwise teeth preceding the fang laterally radially outwards using the upshift indentation formation as movement space, and finally the fang tooth moves first Tooth of the pinion can engage in the engagement space between two link plates. A fang is therefore counterclockwise adjacent to its associated downshift pit formation.

An output tooth and a catcher tooth are physically distinct from other teeth of the sprocket to perform their respective engagement roles in the associated shift. They can have a different tooth height to be measured in the radial direction and/or different tooth width to be measured in the circumferential direction and/or different tooth thickness to be measured in the axial direction and/or different tooth tip shape and/or different shape of at least one tooth flank and/or different from the other pinion teeth Position of one or both tooth side faces relative to the pinion end face closest to it and/and deviating tooth inclination about an inclination axis orthogonal to the radial overhang direction of the tooth and/and deviating tooth inclination about an inclination axis parallel to the radial overhang direction of the tooth, in order to be the last to engage when shifting up Tooth or to act as the first meshing tooth when downshifting.

A chain is usually caught on the larger sprocket of a sprocket pair because of the larger engagement space on an outer plate pair. In addition, outer links and thus pairs of outer links can, due to the system, come closer to a sprocket axially than pairs of inner links, since the outer links facing a larger sprocket of a chain running on a smaller sprocket are always axially closer to the larger sprocket than the inner links facing the larger sprocket.

Since in the case of odd-numbered sprockets, as described above, the assignment of a tooth to the type of chain link meshing with it changes alternately per revolution of the sprocket, in the known sprocket cassette it depends on the number of revolutions that the smaller sprocket guiding the chain has completed before the shifting process , how the chain is transferred to the larger sprocket. In order to securely catch the chain without undesired latency, which is the time interval between the initiation of a shifting process by the driver and the actual execution of the shifting process on the sprocket, two fangs are provided on the larger sprocket, one directly behind the other in the circumferential direction, so that at least one can be used when shifting down engages an outer pair of link plates and will thereby catch the chain.

The same applies, mutatis mutandis, to the output teeth when shifting up.

Catching teeth and delivery teeth are often designed to be thinner than other teeth that do not have to fulfill the tasks of the catching teeth and delivery teeth in order to facilitate the engagement with the chain that is not yet completely or no longer completely rotating on the larger sprocket. This further structurally weakens the fangs and delivery teeth and the pinion as a whole.

Especially with modern electric motor-assisted bicycle drives, compared with the from the EP 1 188 658 B1 well-known chain drive, permanently higher amounts of torque be transmitted. In addition, the gear spread has increased due to the electromotive support of bicycle drives, i.e. the difference in the number of teeth of the largest and the smallest sprocket on a cassette, divided by the number of teeth on the smallest sprocket. In addition, the driving behavior and the shifting behavior on the electric motor-assisted bicycles has changed compared to bicycles powered only by muscle power.

Due to the higher gear spread compared to the past, rear wheel sprocket cassettes with a large number of sprockets must be implemented in order to take into account the desire of cyclists for small gear increments between individual adjacent sprockets. Small gear jumps, i.e. the difference in the number of teeth in a pair of sprockets in relation to the number of teeth on the smaller sprocket, are always required when the bicycle is only driven with muscle power without electric motor support. The trend towards more voluminous tires and shorter chainstays often lead to the use of a relatively small chainring on the pedal crank. As a result, the speed range in which an electromotive support of the driving force of the cyclist is permitted according to the provisions of most road traffic regulations is increasingly shifting towards smaller rear wheel sprockets. In Germany, for example, electric motor assistance is permitted up to a speed of 25 km/h, in other countries up to 20 km/h or up to 30 km/h. Therefore, the smaller sprockets of a sprocket cassette in particular are at risk of increased wear.

It is therefore the object of the present invention to further develop a bicycle/rear wheel sprocket pairing mentioned at the outset in such a way that it can be made more stable without increasing the structural space requirements and can thus be used for operation under higher mechanical loads.

The present invention solves this problem in that the larger sprocket of the bicycle/rear wheel sprocket pairing mentioned at the outset has an even number of teeth equal to or less than 22 teeth, with the difference in the number of teeth between the larger and the smaller sprocket being exactly two teeth. Thus, both sprockets of the sprocket pair are even-numbered sprockets, so that the assignment of the individual sprocket teeth to the chain link type with which they are engaged does not change for the duration of the meshing of the sprocket with the bicycle chain. Thus, if a tooth meshes with an outer-plate chain link in one revolution, this tooth engages with an outer-plate chain link with each revolution of the sprocket.

The larger sprocket has, in its face facing the smaller sprocket, along a portion of its circumference, an upshift area having an upshift indentation formation. As described above, the shift-up range is designed and arranged to allow a change of engagement of the bicycle roller chain from the larger to the smaller sprocket on the pair of rear wheel sprockets rotating clockwise about the sprocket axis.

As a rule, only the upshift range allows the chain to be shifted up to the next smaller sprocket. Also, only one downshift range typically allows the chain to downshift from the next smaller sprocket to the larger sprocket.

If clockwise and counterclockwise are used as directions for the pair of sprockets in the present application, this always refers to a reference view of the pair of sprockets or a sprocket cassette containing the pair of sprockets in the axial direction, with the smaller sprocket of the pair of sprockets being closer to the Viewer located than the larger sprocket. Since the smaller sprocket on the rear wheel of the bicycle carrying the sprocket pair is further away from the longitudinal center plane of the bicycle orthogonal to the sprocket axis and is therefore "further outside" than the larger sprocket, the axial reference view is also referred to below as the axial view "from the outside".

On the larger sprocket, the upshift indentation formation is assigned according to the invention to exactly one delivery tooth, which, due to its shape and orientation, is designed to be the last tooth in cooperation with the front-side upshift indentation formation during an upshifting process from the larger sprocket to the smaller sprocket engages between a pair of tabs of a chain link of the bicycle roller chain. As a rule, only this specially designed output tooth and no other tooth is engaged with the chain when shifting up as the last tooth of the larger sprocket.

The provision of only one delivery tooth per upshift range has two advantages: firstly, the chain is transferred to the smaller wheel in a defined alignment with regard to its chain link sequence, because, unlike in the prior art mentioned above, there are no longer two teeth following one another in the circumferential direction, of which each can act as the last meshing tooth by shape and orientation. The dispensing tooth usually engages in an outer-plate link, since the inner-plate chain link that follows in the counterclockwise direction, as viewed in reference, is considerably simpler due to its narrower dimension can slide past the counterclockwise tooth following the delivery tooth on the face of the larger pinion facing the smaller pinion radially inwards. Secondly, it is sufficient to form only this one delivery tooth as such. As described above, an output tooth is typically axially thinner than a conventional non-output tooth to allow the bicycle chain to move axially toward the smaller sprocket. Thus, the number of teeth structurally weakened by thickness reduction can be reduced on the larger sprocket.

Additionally or alternatively, the larger sprocket has a shift-down area with a shift-down recess formation along its circumference in its end face pointing towards the smaller sprocket. As discussed above, the downshift range is designed to allow a change of engagement of the bicycle roller chain from the smaller to the larger sprocket on the rear wheel sprocket pair rotating clockwise about the sprocket axis.

Additionally or alternatively, the downshift indentation on the larger sprocket is assigned only exactly one fang tooth, which, due to its shape and orientation, is designed to be the first tooth in cooperation with the front downshift indentation during a downshifting process from the smaller sprocket to the larger sprocket , which engages between tabs of a chain link of the bicycle roller chain. As a rule, only the fang is designed to engage in a chain link of the chain as the first tooth when shifting down to the larger sprocket.

Due to the described configuration of the downshift depression formation with only exactly one associated fang, the chain is taken over by the larger sprocket in a defined manner when shifting down from the smaller to the larger sprocket in terms of its chain link sequence. Due to its configuration and orientation, the catching tooth only engages in the chain to be shifted onto the larger sprocket if there is an outer link chain link at the circumferential position of the catching tooth, which provides a larger engagement space than an inner link chain link. If, for whatever reason, an inner plate link is in the place of the fang, the chain will reject. In addition, it also applies here that the formation of only one catching tooth per downshift indentation formation reduces the number of teeth which are structurally weakened in order to implement the catching function.

The larger sprocket of the sprocket pair according to the invention can only have the feature of the upshift recess formation related to the upshifting process with only exactly one assigned delivery tooth, only the feature of the downshift recessed formation related to the downshifting process with only exactly one assigned catch tooth or, particularly advantageously, both features , in order to take over the bicycle chain clearly directed both from the smaller sprocket of the pairing and to hand it over to it.

The basic functional assignment of the output tooth to the upshift depression formation with which it interacts is usually a spatial assignment, because when shifting up, the bicycle chain usually angles towards the smaller sprocket on the chain roller following the meshing output tooth in a counterclockwise direction, wherein at least one of the links following the chain link engaged with the output tooth in a counterclockwise direction dips axially into the upshift valley formation. The upshift indentation is a recess on the face facing the smaller sprocket that provides axial movement space for the chain. Therefore, preferably, the clockwise output tooth immediately follows the upshift valley formation. Preferably, therefore, there is no further tooth in the clockwise direction between the upshift indentation formation and the delivery tooth.

In the case of the above-mentioned sprockets with a number of teeth no greater than 22, it has proven to be sufficient for the larger sprocket to have exactly one upshift area along its entire circumference with only one upshift depression formation and consequently only exactly one output tooth. When an upshift is initiated, it takes place within one sprocket revolution. This is a latency readily accepted by cyclists. The formation of only one upshift depression formation and only one delivery tooth results in the lowest possible weakening of the pinion caused by an upshift process.

For the fang, what was said above for the delivery tooth applies mutatis mutandis mutatis mutandis. First, the chain is brought axially closer to the larger sprocket receiving the chain using the downshift depression formed as an axial recess in the end face and then caught by the catch tooth through positive engagement with a chain link and guided to the larger sprocket. Therefore, the functional association of the fang with its downshift pit formation is also a spatial association. The fang preferably immediately follows the downshift pit formation in a counterclockwise direction. Anti-clockwise is therefore preferred There is no other tooth between the downshift pit formation and the fang.

With a maximum shift latency of one sprocket revolution, with minimal weakening of the larger sprocket due to a downshift, the larger sprocket can have exactly one downshift area along its entire circumference and consequently only exactly one fang.

Tests have shown that it has a positive influence on the wear pattern of the larger sprocket and thus on its overall service life if the catching tooth, starting from the output tooth, has the greatest possible distance from the output tooth in a clockwise direction. The formation of only one delivery tooth and only one catching tooth is also advantageous for achieving this greatest possible distance in the clockwise direction. A large clockwise spacing while at the same time maintaining the boundary conditions necessary for shifting between the larger and the smaller sprocket can be obtained in that, starting from the output tooth, a number k of teeth are located clockwise between the output tooth and the catch tooth, where k = T - d where T is the number of teeth of the larger sprocket and where d is equal to 5 or equal to 7. Don't count the delivery tooth and the fang. Only the teeth located clockwise between the delivery tooth and the fang tooth apply. It is preferable if the number of teeth T of the larger sprocket is an integer divisible by 6 without remainder, d is equal to 5. If the number of teeth T of the larger sprocket is not an integer divisible by 6 without remainder, d is preferably equal to 7 however, it is pointed out that d can also be equal to 7 if the number of teeth T of the larger pinion is an integer divisible by six without a remainder.

With the same objective of the largest possible distance of the fang tooth clockwise from the output tooth of the larger sprocket, the larger sprocket can be designed in such a way that, starting from the fang tooth, there are 3 or 5 teeth clockwise between the fang tooth and the output tooth, with the fang tooth and the delivery tooth are not to be counted.

According to an advantageous but not mandatory development, if the number of teeth of the larger sprocket is divisible by 6 without a remainder, 3 teeth are preferred, and if the number of teeth of the larger sprocket is not divisible by 6 without a remainder, 5 teeth are preferred located clockwise between the fang and delivery teeth.

In order to give the bicycle chain sufficient axial movement possibilities even with a small axial distance between the smaller and the larger sprocket, the tooth following the output tooth in a clockwise direction can be designed as an upshift mobilizing tooth, whose tooth surface facing away from the smaller sprocket is located closer to the smaller sprocket than the tooth surface facing away from the smaller sprocket of the next but one tooth following the mobilization tooth in a clockwise direction. This mobilizing tooth, whose tooth surface facing the smaller sprocket is generally not axially offset compared to the next-but-one clockwise tooth and which is therefore thinner than the next-but-one clockwise tooth, is generally engaged with an inner plate chain link and broaches axial movement play towards the smaller pinion.

Additionally or alternatively, for better axial mobility of the chain, the tooth following the catch tooth in the counterclockwise direction can be designed as a downshift mobilization tooth, the tooth surface of which pointing away from the smaller sprocket is closer to the smaller sprocket than the tooth surface pointing away from the smaller sprocket of the counterclockwise mobilization tooth following next but one tooth. This mobilizing tooth, whose tooth surface facing the smaller sprocket is generally not axially offset compared to the counterclockwise next-but-one tooth and is therefore thinner than the counterclockwise next-but-one tooth, is usually engaged with an inner plate link and broaches axial movement play towards the smaller pinion.

The possibility obtained with the present sprocket pairing of switching the chain from the smaller sprocket to the larger sprocket and/or from the larger sprocket to the smaller sprocket in a defined manner with regard to the sequence of its chain link types can ensure that one and the same tooth of at least one sprocket, preferably both sprockets of the sprocket pair come into meshing engagement not only during the sprocket rotations of an engagement phase, but during all engagement phases of the at least one sprocket with the bicycle chain with one and the same type of chain link.

In principle, all the teeth of the larger and/or the smaller pinion of the pair of pinions can be designed with the same axial thickness for their simplified production. For the most exact possible positioning of the bicycle chain on the pair of sprockets with regard to the chain link sequence relative to the sprocket teeth, the larger sprocket and/or the smaller sprocket can follow one another at least along a circumferential section in the circumferential direction alternately each have an axially thinner and an axially thicker tooth. The thickness of the thicker teeth is advantageously dimensioned in such a way that the thick teeth fit into the engagement space of an outer plate chain link, but not into the engagement space of an inner plate chain link. The thickness of the thinner teeth is advantageously sized to fit within the engagement space of an inner-plate link. As a result, when the chain is properly in mesh with the pinion with alternately thicker and thinner teeth, the chain can be guided on the pinion with very little axial play.

The present application also relates to a bicycle rear wheel sprocket cassette with a plurality of sprockets connected for joint non-slip rotation about the sprocket axis, each with a different number of teeth, the bicycle rear wheel sprocket cassette containing at least one bicycle rear wheel sprocket pairing according to one of the preceding claims. In order to be able to use the advantages of the bicycle rear wheel sprocket pairing described above as extensively as possible on the sprocket cassette, the bicycle rear wheel sprocket cassette preferably has at least three sprockets, each with a different number of teeth, which form two bicycle rear wheel sprocket pairs designed according to the above description, the sprocket with the middle number of teeth the larger pinion of a rear wheel pinion pairing and the smaller pinion of the other rear wheel pinion pairing.

In this sense, all sprockets of the rear wheel sprocket cassette that have 22 teeth or less are particularly preferably designed as bicycle rear wheel sprocket pairings according to the above description. Each sprocket that is not the axial end sprocket of the sprocket group with a number of teeth of 22 or less is the smaller sprocket of a sprocket pairing and at the same time the larger sprocket of another sprocket pairing. By definition, the smallest sprocket in the sprocket group can only be the smaller sprocket in a sprocket pairing.

Since the gear jumps with a constant number of teeth differences become smaller and smaller with larger, i.e. further inner sprockets, it is helpful to achieve fairly even gear jumps over the entire sprocket cassette if the number of teeth difference between adjacent sprockets increases with an increasing number of teeth. In this case, unavoidable differences in the amount of gear steps between adjacent sprockets must be accepted, since sprockets only have integer numbers of teeth and differences in the number of teeth between adjacent teeth are also integers.

Since shifting the chain between two adjacent sprockets can be carried out particularly advantageously when the number of teeth of the adjacent sprockets have at least one common divider, the rear wheel sprocket cassette can have a transition sprocket group comprising a "21-T sprocket" designated sprocket with 21 teeth and a smaller 18-T sprocket with 18 teeth immediately adjacent to this.

The rear wheel sprocket cassette preferably has only exactly one odd-numbered sprocket. This is preferably the aforementioned 21T sprocket.

A sprocket with z number of teeth is referred to below as “z-T sprocket”.

Since the bicycle rear wheel sprocket cassette explained below with the above-mentioned transition sprocket group is an extremely advantageous bicycle rear wheel sprocket cassette even without the bicycle rear wheel sprocket pairing described above, the present application also relates to a bicycle rear wheel sprocket cassette with a plurality of for common non-slip rotation about the Sprockets connected to the sprocket axis, each having a different number of teeth, the sprocket axis defining an axial direction running along the sprocket axis, a radial direction running orthogonally to the sprocket axis and a circumferential direction running around the sprocket axis, and the rear wheel sprocket cassette having a transition sprocket group comprising a 21-T sprocket and a smaller 18T sprocket immediately adjacent to the 21T sprocket. This sprocket cassette can also be further developed as explained below.

The problem here is that on the odd-numbered 21T sprocket, during engagement with the bicycle chain, the association of a sprocket tooth with the chain link type it is engaging changes alternately from revolution to revolution. This means that the chain can be transferred from the 21-T sprocket to the 18-T sprocket in each of the two relative positions in the longitudinal direction of the chain, which can be distinguished with regard to the sequence of chain link types, without any further measures being taken, depending on the number of revolutions during the chain mesh . On the other hand, it can be advantageous to only transfer the chain to the 18-T sprocket in a defined orientation with regard to the sequence of chain link types, so that on the 18-T sprocket there is a defined assignment of a group of teeth to outer plate chain links and of the other set of remaining teeth to inner plate chain links. If the 18-T sprocket is, for example, the larger sprocket of a sprocket pair configured as described above, the correct orientation of the chain on the 18-T sprocket is crucial for the correct orientation of the chain also on the immediately adjacent 16-T sprocket. This can continue towards smaller sprockets.

A defined transfer of the chain from the 21-T sprocket to the 18-T sprocket in a desired assignment of outer-plate chain links to teeth on the 18-T sprocket, which are predetermined and/or designed for engagement only with outer-plate chain links , can be achieved in that the 21-T sprocket has at least two shift-up areas, each with a shift-up recess formation, along a portion of its circumference in its end face pointing towards the 18-T sprocket. Again, each upshift range is designed and arranged to rotate about the pinion axis in a clockwise direction, as viewed in an axial reference of the transitional cogset in a reference condition in which the 18T cog is closer to the viewer than the 21T cog Transition sprocket group to allow a change of engagement of the bicycle roller chain from the 21T sprocket to the 18T sprocket. On the 21-T sprocket, each of the at least two upshift indentations is assigned exactly one output tooth, which is formed by its shape and orientation to interact with the upshift indentation on the face associated with it during an upshift from the 21-T sprocket on the 18T sprocket to be the last tooth to engage between a pair of link plates of a bicycle roller chain link. An even number of teeth, preferably six teeth, are located between the discharge teeth of circumferentially adjacent upshift valley formations, not counting the discharge teeth of adjacent upshift valley formations.

The release tooth, in cooperation with its associated upshift recess formation, usually only allows sufficient axial movement of the chain for shifting the chain from the 21-T sprocket to the 18-T sprocket when the release tooth after initiating a shifting process is engaged with an outer-plate link by the cyclist, such as by shifting the chain guide roller of a rear derailleur. This is the case with the 21T sprocket for one and the same output tooth only every other revolution of the sprocket.

By providing at least one second delivery tooth with an even number of intermediate teeth arranged circumferentially between the two delivery teeth, one of the two delivery teeth is in engagement with an outer plate chain link in one and the same rotation of the pinion, which leads to advantageously short latencies.

Again, by forming only one release tooth per upshift indentation formation, which typically represents a structural weakening of the strength of the release tooth relative to other teeth when compared to other teeth that are not the release tooth, the weakening of the 21-T Pinion can be limited to a minimum level.

Additionally or alternatively, the 21-T sprocket can have at least two shift-down areas, each with a shift-down recess formation, along its circumference on its end face pointing toward the 18-T sprocket. Again, each downshift range is designed to allow a change of engagement of the bicycle roller chain from the 18T sprocket to the 21T sprocket on the transitional cogset rotating clockwise about the sprocket axis when viewing the transitional cogset axially in the datum state. Advantageously, on the 21-T sprocket, only one fang is assigned to each downshift indentation, which, due to its shape and orientation, is designed to interact with the downshift indentation on the front side assigned to it during a downshift process from the 18-T sprocket to the 21-T sprocket to be the first tooth to engage between lugs of a link of bicycle roller chain. Thus, a bicycle chain, which is in a defined assignment of its different types of chain links to the teeth on the even-numbered 18-T sprocket in mesh with the 18-T sprocket, taking into account the defined assignment from the 18-T sprocket to the 21-T sprocket. pinions are shifted. To achieve short latencies, an even number of teeth are located between the fangs of circumferentially adjacent downshift valleys, not counting the fangs of adjacent downshift valleys.

Here, too, it applies that a fang on the 21-T sprocket, in cooperation with the downshift depression formation assigned to it, can only engage a bicycle chain that is sufficiently axially close to the 21-T sprocket for catching if the fang tooth engages in an outer plate Chain link can intervene. Due to the arrangement described above, this is always the case for one of the two fangs.

Because, as with the output tooth, only one fang is associated with each downshift indentation, the pinion is weakened locally in the area of the downshift indentation only to the extent necessary. The latency is increased by the further fang or delivery tooth arranged at a distance from the first fang or delivery tooth, but the weakening of the pinion is locally limited by the formation of the catching tooth or delivery tooth and is distributed to peripheral points arranged at a distance from one another. This increases the wear resistance of the entire pinion. Overall, the slightly increased switching latency is overcompensated by the increased wear resistance.

1. i) genau drei Hochschaltbereiche mit je einer Hochschalt-Vertiefungsformation und je genau einem Abgabezahn aufweist, wobei zwischen den Abgabezähnen von in Umfangsrichtung benachbarten Hochschalt-Vertiefungsformationen jeweils eine gerade Anzahl an Zähnen, vorzugsweise sechs Zähne, gelegen sind, wobei die Abgabezähne der benachbarten Hochschalt-Vertiefungsformationen nicht mitzuzählen sind,

oder/und

• ii) genau drei Herunterschaltbereiche mit je einer Herunterschalt-Vertiefungsformation und je genau einem Fangzahn aufweist, wobei zwischen den Fangzähnen von in Umfangsrichtung benachbarten Herunterschalt-Vertiefungsformationen jeweils eine gerade Anzahl an Zähnen, vorzugsweise sechs Zähne, gelegen sind, wobei die Fangzähne der benachbarten Herunterschalt-Vertiefungsformationen nicht mitzuzählen sind.

Even shorter shift latencies can be obtained when the 21T sprocket

1. i) has exactly three upshift areas, each with an upshift depression formation and each with exactly one delivery tooth, with an even number of teeth, preferably six teeth, being located between the delivery teeth of circumferentially adjacent upshift depression formations, the delivery teeth of the adjacent upshift deepening formations are not to be counted,

or and

• ii) has exactly three downshift areas, each with one downshift indentation and each with exactly one fang, wherein an even number of teeth, preferably six teeth, are located between the fangs of circumferentially adjacent downshift indentations, the fangs of the adjacent downshift Deepening formations are not to be counted.

In order to increase wear resistance, the catch teeth are preferably distributed equidistantly around the circumference of the 21-T sprocket and/or the delivery teeth are distributed equidistantly around the circumference of the 21-T sprocket.

A particularly advantageous synergistic effect is obtained by arranging a fang tooth as a direct neighbor of a donor tooth. Preferably, the catching tooth is clockwise adjacent to the dispensing tooth. Since only exactly one fang can actually catch the chain during a sprocket rotation, each tooth is considered a fang that corresponds in its physical design to the actual catching tooth. As described above, the fang is not only thinner than a regular tooth, but its tooth surface facing away from the smaller sprocket is closer to the smaller sprocket compared to regular teeth of the 21-T sprocket. Thus, such a clockwise fang adjacent the output tooth can serve as an upshift mobilizing tooth as described above, allowing axial movement of the chain to facilitate shifting to the 18T sprocket.

Likewise, the delivery tooth consequently counterclockwise adjacent to the fang, which by virtue of its function is also thinner than a regular tooth of the 21T sprocket and its tooth surface facing away from the smaller sprocket, compared to a regular tooth of a 21T sprocket the smaller sprocket, the fang serves as a downshift mobility tooth which allows the inner-plate link following the fang-engaged outer-plate links in a counter-clockwise direction both into close proximity to the smaller 18T sprocket and into the smaller engagement space of the inner-plate link can engage meshing.

Such an arrangement of a pair of a delivery tooth and a fang tooth immediately adjacent to the delivery tooth in a clockwise direction ensures a particularly defined shifting behavior both from the 18-T sprocket to the 21-T sprocket and in the opposite shifting direction. Preferably, more than one pair of such an output tooth and a fang tooth clockwise adjacent to the output tooth are disposed on the 21-T sprocket. For example, two or three such pairs may be located on the 21T sprocket.

Both the delivery tooth and the catching tooth immediately adjacent clockwise, which are mutually configured as mobilization teeth, are preferably provided with a ramp on their side facing away from the 18-T sprocket, on which a link plate can be supported by radial contact engagement. The ramp has a ramp surface pointing radially outwards, which is preferably formed by a stepped configuration of the dispensing tooth and the catching tooth. To achieve the stepped configuration, a section of the delivery tooth and catching tooth that is located radially further outward can be made thinner than a section of the delivery tooth or catching tooth that is located radially further inwards. The ramp surface, the axial dimension of which is preferably at least 50% of the thickness of an outer plate of the bicycle chain interacting with the sprocket or sprocket cassette in order to provide the chain with sufficient support surface, can be inclined towards the next largest sprocket adjacent to the 21-T sprocket , where the radial component of the normal vector of the ramp surface is larger in magnitude than its axial component. An opposite inclination of the ramp surface to the 18-T sprocket is possible in principle, but not preferred, since the ramp surface could then form a V-groove with the tooth surface facing away from the 18-T sprocket, in which dirt collects.

The ramp surface can be a flat surface. To achieve the largest possible system surface of a chain link on the ramp surface and thus the safest possible support of the chain radially on the outside of the ramp, the ramp surface can be designed at least in sections complementary to a radially inward-pointing edge of the chain link, in particular the inner link, of the circulating bicycle chain.

In order to provide transmission ratios that enable a high torque on the rear wheel, i.e. to transmit the chain ring rotation on the pedal crank more strongly than quickly, the transition sprocket group is preferably additionally equipped with a 24-T sprocket, with the 21-T sprocket is located axially between the 24T sprocket and the 18T sprocket.

For a transfer of the bicycle chain from the 21-T sprocket to the 24-T sprocket, which is advantageous in terms of the chain link sequence, so that predetermined teeth of the 24-T sprocket are safely transferred to outer plate chain links for meshing engagement, the 24-sprocket can be in its the end face pointing towards the 21-T sprocket, have at least two shift-down areas along its circumference, each with a shift-down recess formation.

On the 24-T sprocket, each downshift indentation is assigned exactly one fang, which, due to its shape and orientation, is designed to interact with the downshift indentation on the face associated with it during a downshift from the 21-T sprocket to the 24th gear -T-sprocket to be the first tooth to engage between lugs of a chain link of bicycle roller chain. The chain link of the bicycle roller chain that engages with the fang is usually an outer-plate link, since this can be brought axially further into the engagement area of the fang in cooperation with the downshift depression formation than an inner-plate chain link.

An odd number of teeth are located between the fangs of circumferentially adjacent downshift indentations, not counting the fangs of adjacent downshift indentations, such that within one revolution of the 24T sprocket, regardless of the relative orientation of the 21st chain -T sprocket comes off, making sure a fang tooth engages an outer plate link. This leads to advantageously short shifting latencies while at the same time reducing the structural weakening of the 24-T sprocket.

Additionally or alternatively, the 24-T sprocket can have at least two shift-up areas, each with a shift-up recess formation, along a portion of its circumference on its end face pointing toward the 21-T sprocket.

To increase its resistance to wear, each of the two upshift indentations on the 24-T sprocket has only one delivery tooth assigned to it, which, due to its shape and orientation, is designed to interact with the upshift indentation on the face assigned to it during an upshift from 24 to T sprocket on the 21T sprocket to be the last tooth that engages between a pair of link plates of the bicycle roller chain.

To achieve short shift latencies during upshifts, the 24T sprocket preferably has an odd number of teeth located between the output teeth of circumferentially adjacent upshift indentations. The delivery teeth of the adjacent upshift depression formations are not to be counted.

Even shorter shifting latencies can be obtained in that the 24-T sprocket has exactly three upshift areas, each with one upshift indentation and each with exactly one output tooth, with an odd number between the output teeth of circumferentially adjacent upshift indentations, for uniform distribution the latencies along the circumference of the sprocket are preferably located at seven teeth, not counting the output teeth of the adjacent upshift depression formations,
and/or that the 24-T sprocket has exactly three downshift areas, each with one downshift indentation and each with exactly one fang tooth, with an odd number, preferably seven, teeth located between the fangs of circumferentially adjacent downshift indentation formations, with the Not counting fangs of adjacent downshift pit formations.

In order to achieve an unambiguous assignment of sprocket teeth to chain link types engaged by them on as many sprockets as possible, the bicycle rear wheel sprocket cassette has as many even-numbered sprockets as possible. Therefore, the sprocket cassette preferably comprises a first set of directly axially adjacent sprockets of different sizes, between which the number of teeth differs by 2 teeth. These teeth are preferably formed with orientation formations which allow the sprockets to engage with the chain only in a predetermined orientation of the chain link sequence relative to the sprockets. Such orientation formations may include at least one thicker tooth described above, wel cher is located circumferentially between two thinner teeth and allows engagement with only one outer plate link.

This first set is preferably followed by at least one sprocket which has a tooth number difference of 3 teeth from the largest sprocket of the first set. So that the bicycle rear sprocket cassette has only a small number of odd-numbered sprockets, the cassette preferably comprises a second set of sprockets of different sizes, of which axially adjacent sprockets each have a tooth number difference of 3 teeth. This second set preferably contains an even number of sprockets, preferably two sprockets. Even-numbered sprockets of this second set are preferably again formed with the above-mentioned orientation formations, which allow engagement of the sprockets with the chain only in a predetermined orientation of the chain link sequence relative to the sprockets.

The second set can be followed by a third set of even-numbered sprockets of different sizes, the smallest sprocket of the second set and the axially adjacent sprockets each having a tooth number difference of 4 teeth. In turn, each sprocket of the third set preferably has the above-mentioned orientation means for relative alignment of the chain relative to the sprockets with regard to their chain link sequence.

A particularly preferred bicycle rear sprocket cassette that meets the above criteria is a twelve-speed sprocket cassette with the following number of teeth gradation: 10-12-14-16-18-21-24-28-32-38-44-52 For the reasons mentioned, all pinion pairings with a number of teeth less than 21 are preferably designed as the rear wheel pinion pairings described above.

The ramp surface described above in connection with the 21-T sprocket can also be formed on the sprockets of the sprocket cassette with a larger number of teeth than 21, for example on the sprockets located between the chain line and the longitudinal center plane of the bicycle orthogonal to the sprocket axis. The above description of the ramp surface also applies to the ramp surfaces preferably formed on the pinions with a number of teeth greater than 21. The ramp surface extends over at least, preferably exactly two adjacent teeth and forms a radial and axial step on the side of a pinion facing away from the next smaller pinion. The two adjacent teeth over which the ramp surface extends are, on the sprockets with a number of teeth greater than 21, usually not a pair of a delivery tooth and a catching tooth immediately adjacent to it. The formation preferably takes place on at least one mobilization tooth. The canine or delivery tooth adjacent to a ramped mobilizing tooth may also have a ramp. Preferably, the ramp of a canine tooth and/or a delivery tooth is radially further outward than the ramp of a mobilization tooth immediately adjacent to the canine tooth or delivery tooth. Even the largest sprocket can have a ramp surface on its side facing away from the next smaller sprocket or have several ramp surfaces distributed along its circumference.

As described above, the ramp surfaces can, with larger sprockets, support the chain by contacting link plates radially on the outside of the ramp surface and thus prevent the bicycle chain from shifting undesirably to the next smaller sprocket when pedaling backwards using the usual freewheel of the sprocket cassette. With an increasing number of teeth, the sprockets are increasingly removed from the chain line, so that when the bicycle chain engages with larger sprockets, the bicycle chain becomes increasingly inclined relative to the longitudinal center plane of the bicycle that is orthogonal to the sprocket axis. When pedaling backwards, this chain skewing can lead to an undesired shifting movement of the chain to the next smaller sprocket and thus to a lesser amount of skewing on larger sprockets that are therefore closer to the longitudinal center plane of the bicycle. The ramp surface can counteract this.

On smaller sprockets, with a number of teeth of 22 teeth and less, shifting-supporting ramps can be formed on the tooth surfaces on the side pointing to the next smaller sprocket. Since these sprockets are generally located axially outside of the chain line, individual chain links can be held stable on the ramps on the outward-facing tooth surface by the chain skewing or chain skewing.

Radially inner edges of inner plate chain links pointing towards the pinion axis are preferably supported on ramps of this type. The ramps have a support surface pointing radially outwards. Here, in interaction with a tooth head of an axially adjacent smaller sprocket that is axially spaced apart from a ramp, both inner link plates of one and the same inner link chain link can be physically supported radially inward when the chain is shifted between the smaller sprocket and the larger sprocket that carries the ramp on the side facing the smaller sprocket be. The inner link located axially further inwards can be supported by the ramp and the inner link located axially further outwards can be supported by the tooth head, in particular by a surface of the tooth head pointing radially outward. The support can take place both when shifting down and when shifting up.

However, it is also conceivable that only the inner plate located axially further inwards is supported on a ramp on the side of a pinion pointing towards the smaller pinion, in particular a tooth surface, during a shifting operation.

The present application also relates to a bicycle drive assembly comprising a bicycle rear sprocket pairing as described above and/or a bicycle rear sprocket cassette as described above having a gear for meshing, power-transmitting engagement with the sprockets of the bicycle rear sprocket pairing or the bicycle rear wheel sprocket cassette, wherein the bicycle roller chain has a plurality of chain rollers which follow one another at a pitch and which are connected to one another by pairs of parallel link plates, the bicycle roller chain having pairs of inner link plates with a smaller link spacing and outer link plates alternating in the direction of chain circulation having a larger tab spacing consecutively.

The bicycle drive train may have a single chainring in the area of the cranks such that any change in transmission ratio from the front chainring to the rear sprocket cassette is accomplished only by changing the chain engagement with one of the sprockets of the sprocket cassette.

For engagement with the twelve-speed sprocket cassette preferred above, a bicycle chain is preferred whose chain plates have a straight edge section on the radially outer edge between the two chain roller axes connected by a chain plate and whose chain plates have a curved edge line on the radially inner edge such that the chain plates are orthogonal to the chain roller axis and the plate height to be measured orthogonally to the direction of rotation of the chain is lower in an area between the chain roller axes than in the area of the chain roller axes. In this way, a narrow yet sufficiently strong bicycle chain is obtained.

In order to achieve a fast, precise shifting process with little axial movement of the bicycle chain in a shifting section between the currently chain-guiding sprocket and the future chain-guiding sprocket, it is preferable for at least one bicycle rear wheel sprocket pairing, more preferably for several bicycle rear wheel sprocket pairs, that during a shifting process in which the bicycle roller chain is shifted from one sprocket to a sprocket axially adjacent to it, in the shifting section between the last chain link that is in engagement with the sprocket that is still guiding the chain and the first chain link that is or is coming into engagement with the sprocket that will be chain-guiding in the future , there is exactly one inner plate chain link. There is preferably only exactly one inner plate chain link in the folding section. Although it should not be ruled out that this shifted condition can also apply to pinion pairings with a tooth spacing of more than two teeth between the larger and smaller sprocket, the shifted condition applies in particular to pinions with a difference in the number of teeth of two teeth.

• 1 eine erfindungsgemäße Fahrrad-Hinterradritzelkassette bei Bezugsbetrachtung längs der Ritzelachse, wobei zunehmend größere Ritzel mit zunehmendem Abstand vom Betrachter angeordnet sind,
• 1A die Ritzelkassette von 1 mit Blickrichtung orthogonal zur Ritzelachse,
• 1B die Ritzelkassette von 1 mit entgegengesetzter Blickrichtung von der Längsmittelebene weg,
• 2A eine erste erfindungsgemäße Fahrrad-Hinterradritzelpaarung der Ritzelkassette der 1 bis 1B mit einem kleineren Ritzel mit 10 Zähnen und einem größeren Ritzel mit 12 Zähnen bei Bezugsbetrachtung,
• 2B die Fahrrad-Hinterradritzelpaarung von 2A in entgegengesetzter Richtung betrachtet,
• 3A eine zweite erfindungsgemäße Fahrrad-Hinterradritzelpaarung der Ritzelkassette der 1 bis 1B mit einem kleineren Ritzel mit 12 Zähnen und einem größeren Ritzel mit 14 Zähnen bei Bezugsbetrachtung,
• 3B die Fahrrad-Hinterradritzelpaarung von 3A in entgegengesetzter Richtung betrachtet,
• 4A eine dritte erfindungsgemäße Fahrrad-Hinterradritzelpaarung der Ritzelkassette der 1 bis 1B mit einem kleineren Ritzel mit 14 Zähnen und einem größeren Ritzel mit 16 Zähnen bei Bezugsbetrachtung,
• 4B die Fahrrad-Hinterradritzelpaarung von 4A in entgegengesetzter Richtung betrachtet,
• 4C die dritte erfindungsgemäße Fahrrad-Hinterradritzelpaarung der Ritzelkassette von 4A beim Herunterschalten einer Fahrradkette vom 14-T-Ritzel auf das 16-T-Ritzel, bei Bezugsbetrachtung,
• 4D die Fahrrad-Hinterradritzelpaarung von 4C in entgegengesetzter Richtung betrachtet,
• 4E die dritte erfindungsgemäße Fahrrad-Hinterradritzelpaarung der Ritzelkassette von 4A beim Hochschalten einer Fahrradkette vom 16-T-Ritzel auf das 14-T-Ritzel, bei Bezugsbetrachtung,
• 4F die Fahrrad-Hinterradritzelpaarung von 4E in entgegengesetzter Richtung betrachtet,
• 5A eine vierte erfindungsgemäße Fahrrad-Hinterradritzelpaarung der Ritzelkassette der 1 bis 1B mit einem kleineren Ritzel mit 16 Zähnen und einem größeren Ritzel mit 18 Zähnen bei Bezugsbetrachtung,
• 5B die Fahrrad-Hinterradritzelpaarung von 5A in entgegengesetzter Richtung betrachtet,
• 6 eine Fahrrad-Hinterradritzelpaarung der Ritzelkassette der 1 bis 1B mit einem kleineren Ritzel mit 18 Zähnen und mit einem größeren Ritzel mit 21 Zähnen bei Bezugsbetrachtung, wobei die Hinterradritzelpaarung zu einer Übergangs-Ritzelgruppe mit insgesamt drei Ritzeln gehört,
• 7 eine Fahrrad-Hinterradritzelpaarung der Ritzelkassette der 1 bis 1B mit einem kleineren Ritzel mit 21 Zähnen und mit einem größeren Ritzel mit 24 Zähnen bei Bezugsbetrachtung, wobei die Hinterradritzelpaarung zu der Übergangs-Ritzelgruppe mit insgesamt drei Ritzeln gehört,
• 8 die Fahrrad-Hinterradritzelpaarung von 7 mit einer Fahrradkette, welche mit dem größeren Ritzel im Eingriff ist und herunter auf das kleinere Ritzel geschaltet wird,
• 9 eine Fahrrad-Hinterradritzelpaarung der Ritzelkassette der 1 bis 1B mit einem kleineren Ritzel mit 24 Zähnen und einem größeren Ritzel mit 28 Zähnen,
• 10 das größte Ritzel der Ritzelkassette der 1 bis 1B bei Bezugsbetrachtung,
• 10A das Ritzel von 10 mit einer Betrachtungsrichtung orthogonal zur Ritzelachse,
• 10B das Ritzel von 10 bei Betrachtung längs der Ritzelachse mit Blickrichtung von der Längsmittelebene weg, und
• 11 ein mit der Ritzelkassette der 1 bis 1B ausgestattetes Fahrrad.

The present invention is explained in more detail below with reference to the accompanying drawings. It shows:

• 1 a bicycle rear sprocket cassette according to the invention as viewed in relation along the sprocket axis, with progressively larger sprockets arranged with increasing distance from the viewer,
• 1A the sprocket cassette from 1 with viewing direction orthogonal to the pinion axis,
• 1B the sprocket cassette from 1 facing away from the median longitudinal plane,
• 2A a first bicycle rear wheel sprocket pairing of the sprocket cassette according to the invention 1 until 1B with a smaller sprocket with 10 teeth and a larger sprocket with 12 teeth when viewed as a reference,
• 2 B the bicycle rear wheel sprocket pairing from 2A viewed in the opposite direction
• 3A a second bicycle rear wheel sprocket pairing of the sprocket cassette according to the invention 1 until 1B with a smaller sprocket with 12 teeth and a larger sprocket with 14 teeth when viewed as a reference,
• 3B the bicycle rear wheel sprocket pairing from 3A viewed in the opposite direction
• 4A a third bicycle rear wheel sprocket pairing of the sprocket cassette according to the invention 1 until 1B with a smaller sprocket with 14 teeth and a larger sprocket with 16 teeth when viewed as a reference,
• 4B the bicycle rear wheel sprocket pairing from 4A viewed in the opposite direction
• 4C the third bicycle rear wheel sprocket pairing of the sprocket cassette according to the invention 4A when shifting down a bicycle chain from the 14-T sprocket to the 16-T sprocket, in reference consideration,
• 4D the bicycle rear wheel sprocket pairing from 4C viewed in the opposite direction
• 4E the third bicycle rear wheel sprocket pairing of the sprocket cassette according to the invention 4A when shifting up a bicycle chain from the 16-T sprocket to the 14-T sprocket, in reference consideration,
• 4F the bicycle rear wheel sprocket pairing from 4E viewed in the opposite direction
• 5A a fourth bicycle rear wheel sprocket pairing of the sprocket cassette according to the invention 1 until 1B with a smaller sprocket with 16 teeth and a larger sprocket with 18 teeth when viewed as a reference,
• 5B the bicycle rear wheel sprocket pairing from 5A viewed in the opposite direction
• 6 a bicycle rear wheel sprocket pairing of the sprocket cassette 1 until 1B with a smaller sprocket with 18 teeth and with a larger sprocket with 21 teeth when viewed as a reference, with the rear wheel sprocket pairing belonging to a transition sprocket group with a total of three sprockets,
• 7 a bicycle rear wheel sprocket pairing of the sprocket cassette 1 until 1B with a smaller sprocket with 21 teeth and with a larger sprocket with 24 teeth when viewed as a reference, the rear wheel sprocket pairing belonging to the transition sprocket group with a total of three sprockets,
• 8th the bicycle rear wheel sprocket pairing from 7 with a bicycle chain, which is engaged with the larger sprocket and is shifted down to the smaller sprocket,
• 9 a bicycle rear wheel sprocket pairing of the sprocket cassette 1 until 1B with a smaller sprocket with 24 teeth and a larger sprocket with 28 teeth,
• 10 the largest sprocket of the sprocket cassette 1 until 1B when considering reference,
• 10A the pinion of 10 with a viewing direction orthogonal to the pinion axis,
• 10B the pinion of 10 when viewed along the pinion axis looking away from the median longitudinal plane, and
• 11 one with the sprocket cassette the 1 until 1B equipped bike.

In 1 is a preferred embodiment according to the invention of a bicycle rear sprocket cassette with twelve coaxial, slip-free for common rotation about the plane of the drawing 1 orthogonal pinion axis R interconnected pinions generally denoted by 1.

Considering the sprocket cassette 1 in 1 corresponds to the reference consideration previously described in the introduction to the description, ie viewed along the pinion axis R, with the smallest pinion being viewed from 1 is closest and the largest sprocket in the viewer of 1 is farthest away.

The number of teeth gradation of the sprocket cassette 1 from 1 is: 10 - 12 - 14 - 16 - 18 - 21 - 24 - 28 - 32 - 38 - 44 - 52. The sprocket cassette 1 thus includes a smallest sprocket 10 with ten teeth, a sprocket 12 with 12 teeth axially adjacent to this one next larger pinion 14 with 14 teeth, in turn next larger pinion 16 with 16 teeth, and an axially adjacent pinion 18 with 18 teeth.

The next largest sprocket 20 adjacent to sprocket 18 is a transition sprocket with 21 teeth. This is followed by a pinion 22 with 24 teeth, a pinion 24 with 28 teeth, in pinion 26 with 32 teeth, in pinion 28 with 38 teeth, a pinion 30 with 44 teeth and finally as the largest pinion a pinion 32 with 52 teeth.

Of these sprockets 10 to 32, the immediately adjacent sprocket pairings of the sprockets 10 to 18 each form a bicycle rear wheel sprocket pairing according to the invention as described above.

The sprockets 12 to 16 are each sprockets of two sprocket pairs, once as a smaller sprocket of the sprocket pair and once as a larger sprocket of the sprocket pair. To form the sprockets 10 and 12 a bicycle-rear wheel sprocket pairing 11, the sprockets 12 and 14 a bicycle-rear wheel sprocket pairing 13, the sprockets 14 and 16 a bicycle-rear wheel sprocket pairing 15 and the sprockets 16 and 18 a bicycle-rear wheel sprocket pairing 17.

The two sprockets 18 and 22 axially adjacent to the only odd-numbered transition sprocket 20 in the sprocket cassette 1 together with the transition sprocket 20 form a transition sprocket group 19.

To facilitate shifting between axially adjacent sprockets, the sprockets, except for the smallest sprocket 10, each have at least one upshift portion 34 with an upshift indentation 36 and an output tooth 38, and each have at least one downshift portion 40 with a down switching depression formation 42 and a fang 44 on.

For the sake of clarity, in 1 only the largest sprocket 32 with 52 teeth is provided with reference numbers for the upshift range 34 with the upshift indentation 36 and the output tooth 38 and for the downshift range 40 with the downshift indentation 42 and the catch tooth 44.

The areas: upshift area 34 and downshift area 40 always relate to the pinion on which the areas are formed. This means that the upshift area 34 facilitates a transfer of a bicycle chain from the sprocket carrying the upshift area 34 to the axially adjacent next smaller sprocket and the downshift area 40 facilitates a transfer of the bicycle chain from the next smaller sprocket to the sprocket carrying the downshift area 40 .

The depression formations 36 and 42 allow the bicycle chain to approach the sprocket bearing the respective depression formations axially, since in particular outer plates can dip into the depression formations designed as axial front-side recesses. Without the formation of indentation formations at the points mentioned, the outer link plates of the bicycle chain would collide with the end face of the sprocket, which would limit the axial approach of the bicycle chain to the end face having the indentation formations.

The depression formations 36 and 42 can have a number of different surface facets, which can have a different position relative to one another with respect to the pinion axis R and/or a different inclination. This means that the bicycle chain can only dip into the depression formations 36 or 42 in a predetermined relative position with respect to its outer plates and inner plates and is axially deflected by a surface facet when the relative position is offset by one chain pitch in the direction of chain circulation. The surface facet can be designed in such a way that it can penetrate into the intermediate space between two outer plates that follow one another in the direction of chain circulation towards an inner plate that is located between the outer plates, but an outer plate that is located between two inner plates physically deflects axially away from the pinion that carries it.

Catching teeth 44 of the individual sprockets of the rear wheel cassette 1 lie on a helix 45 rotating counterclockwise radially outwards when the rear wheel cassette 1 is viewed in relation.

In 1A the sprocket cassette 1 is shown with a viewing direction orthogonal to the sprocket axis R. For explanation, the previously mentioned longitudinal center plane LME, which is orthogonal to the pinion axis R, of the bicycle carrying the pinion cassette 1 is shown in dashed lines. The actual distance between the longitudinal center plane LME and the sprocket cassette 1 is greater than in the shortened representation of FIG 1A .

The pinions 10 to 30 are preferably formed in one piece as a so-called pinion dome, for example by machining from the solid. Deviating from this, the two smallest sprockets 10 and 12 can alternatively be designed as individual sprockets. The two smallest sprockets 10 and 12 can then be connected to the sprocket dome of the sprockets 14 to 30 via a slotted nut. The largest pinion 32 is formed as a single pinion. The pinion dome can be connected in a manner known per se with pins or rivets or with a material connection to the struts of the pinion 32 for the transmission of torque.

The axial distance between the pinions that are directly adjacent to one another is generally smaller than the tooth height of a regularly shaped tooth of the pinion. The small axial distance between the individual sprockets requires a very narrow chain and an extremely precise design of the toothed peripheral areas of the individual sprockets.

1B shows the sprocket cassette 1 from the inside, ie viewed from the longitudinal center plane LME along the sprocket axis R. As far as the smaller sprockets can be seen through the passages formed between the struts of the largest sprocket 32, they are denoted by reference numerals. Otherwise, for further description of the largest sprocket, refer to the explanation below 10 until 10B referred.

2A shows the smallest bicycle rear wheel sprocket pair 11 of the sprocket cassette 1 in relation to each other. 2 B shows the same bicycle rear wheel sprocket pairing 11 when viewed axially, but "from the inside", ie in such a way that the larger sprocket 12 the viewer from 2 B is closer than the smaller sprocket 10.

The smaller pinion 10 is preferably designed as a synchronizing pinion with thicker teeth 10a and with thinner teeth 10b. The axial thickness of the thicker teeth 10a is selected in such a way that they only fit into the engagement space of an outer plate chain link, but are thicker than the distance between two parallel inner plates of an inner plate chain link. A bicycle chain can therefore follow along with you in relation to the Alternating chain link types only mesh with the pinion 10 in exactly one relative orientation, namely when the thicker teeth 10a are associated with outer plate chain links. Because of the even number of chain links in a bicycle chain revolution and because of the even number of teeth of the sprocket 10, once a tooth has been assigned to a chain link type, it is maintained over all sprocket revolutions for the entire duration of engagement of the sprocket 10 with the chain.

A tooth 10c of the smallest sprocket 10 has a rounded and thereby radially shortened tooth head in order to make it easier to switch the bicycle chain from the sprocket 10 to the next larger sprocket 12 that is axially adjacent and to prevent the chain from colliding with the tooth 10c.

Exactly one upshift area 34 with exactly one upshift depression formation 36 and exactly one release tooth 38 directly adjacent to the upshift depression formation 36 in a clockwise direction is formed on the larger sprocket 12 of the sprocket pair 11 . The output tooth 38 is the first clockwise tooth which is not altered on its tooth surface facing the smaller sprocket 10 by the upshift dimple formation 36 . Thus, the output tooth 38 is the first tooth clockwise to which the upshift valley formation 36 no longer extends.

Exactly one downshift area 40 is also formed on the larger sprocket 12, which has a shorter distance to the upshift area 34 in the counterclockwise direction than in the clockwise direction. The single downshift groove 42 no longer extends counterclockwise to the single fang 38, which is thus the first unshaped tooth from the downshift groove 42 following the downshift groove 42 in the counterclockwise direction.

The arrow D running in the circumferential direction shows the driving direction of rotation of the pinion pair 11 in the driving mode at the in 11 bike 70 shown.

As can be seen on the rear view of sprocket 12 from 2 B recognizes that the sprocket 12 also has thicker teeth 12a and thinner teeth 12b, of which the thicker teeth 12a can only mesh in outer plate chain links due to their thickness. The distance between two parallel inner plates of an inner plate chain link is less than the thickness of the teeth 12a. Consequently, the bicycle chain can also rotate on the larger sprocket 12 only in a specific relative position, namely when the teeth 12a are each assigned an outer link chain link.

By using only one delivery tooth 38 and only one catching tooth 44, a directed transfer of the bicycle chain with the relative position between the sprockets 10 and 12 necessary for meshing engagement with the respective sprocket 10 or 12 can take place reliably. Only exactly one tooth needs to be weakened for each shifting direction, which results in a larger pinion 12 that is wear-resistant overall.

The arrangement of the catch tooth 44 and the delivery tooth 38 along the circumference of the larger sprocket 12 in the form shown has a further wear-reducing effect on the second smallest sprocket 12 of the cassette 1, because the upshift area 34 and the downshift area 40 merge into one another, which weakens a very small number of teeth by the depression formations 36 and 42 means. Thus, many teeth can be formed with the largest possible load flanks, which gives them good load-carrying capacity. With increasing load-carrying capacity of the pinion 12, its tendency to wear decreases compared to a lower load-carrying capacity of the pinion 12. Starting from the catching tooth 44, three teeth of the larger pinion 12 of the pinion pair 11 lie clockwise between the catching tooth 44 and the output tooth 38 in the exemplary embodiment shown.

Starting from the delivery tooth 38, there are seven teeth of the larger pinion 12 between the delivery tooth 38 and the catching tooth 44, this corresponds to the number of teeth of the pinion 12 minus 5. It has been shown that starting from the delivery tooth 38, the greatest possible distance of the catching tooth 44 in a clockwise direction from the delivery tooth 38 leads to an advantageous wear pattern of the sprocket 12 during operation, in particular when the bicycle equipped with the sprocket cassette 1 is driven by an electric motor and thus, compared to driving by pure muscle power, a higher torque is permanently exerted on the smaller sprockets of the Sprocket cassette 1 is transferred. In the example shown, these smaller sprockets are sprockets 10 through 18.

On the central tooth of the three teeth located clockwise between the catch tooth 44 and the output tooth 38, a deflector surface 12d is formed which is part of both the downshift indentation 42 and the upshift indentation 36. The deflecting surface 12d, which is recessed relative to the end surface of the pinion 12 but is raised relative to its circumferentially adjacent recessed portion and protrudes axially, is designed to engage in the space between two outer plates fen. If during the shifting process, for whatever reason, there is an outer plate instead of an inner plate at the point of deflection surface 12d, the chain is physically moved by the outer plate lying against the deflection surface 12d at an axial approach to the end face of the chain that is necessary for shifting the chain Sprocket 12 prevented and the chain thus rejected.

When shifting down the chain from sprocket 10 to sprocket 12, an inner edge 54c pointing radially inwards (see 8th ) an inner plate of an inner plate chain link 54 (see 8th ) are physically supported on a radially outward facing crest surface 10cf of tooth 10c. The inner edge 54c is between the chain roller axles 55 (see Fig. 8th ) concave shaped. The head face 10cf is therefore convex in shape for the most planar and secure support possible, with the leading end of the head face 10cf in the driving direction of rotation D being located radially further inwards than the trailing end of the head face 10cf. Preferably, the convex shape of the top surface 10cf is complementary to the concave inner edge 54c of the chain 50.

The pinion pairing 11 has a special feature here: the tooth of the pinion 12 lying behind the tooth 10c when viewed as a reference has a deflection surface 12h on its tooth surface pointing towards the smaller pinion 10, which is part of the downshift recess 42 of the downshift area 40. An inner-plate chain link on the side of the sprocket 12 facing the smaller sprocket 10 can pass this deflecting surface 12h towards the catch tooth 44 of the sprocket 12, but an outer-plate chain link cannot.

The deflection surface 12h ends radially on the inside at a ramp 12c1, which has a radially outward-facing, preferably likewise convexly curved, support surface that protrudes axially relative to the deflection surface 12h.

When shifting down from sprocket 10 to sprocket 12, an inner-plate chain link can therefore be supported with its two inner plates on the pair of sprockets, namely with the inner plate lying further axially on the outside on the head surface 10cf and with the inner plate lying further inside on the ramp 12c1. In this way, the chain can be guided well in the folding section. The chain skewing when the chain meshes with the sprockets 10 and 12 that are axially outside the chain line supports the contact of the inner plate on the deflector surface 12h and on the ramp 12c1, because on sprockets that are outside the chain line, the chain skewing causes an axially inward force on the engaging sprocket.

the 3A and 3B show the bicycle rear sprocket pairing 13 with the already from the 2A and 2 B known pinion 12, this time as a smaller pinion pairing 13, and with the pinion 14 as a larger pinion. 3A shows the bicycle rear wheel sprocket pair 13 when viewed from the outside, 3B shows the bicycle rear wheel sprocket pair 13 viewed axially in the opposite direction, ie from the inside.

On the larger sprocket 14 of the pair of sprockets 13, the same types of teeth or tooth surfaces are denoted by the same lower-case letters as on the sprocket 12. The pair of sprockets 13 also has exactly one upshift area 34 with exactly one upshift depression formation 36 and exactly one release tooth 38 to increase its wear resistance. The shift-up recess formation 36 of the sprocket 14 in turn has surface facets, all of which are arranged axially recessed relative to the end face of the sprocket 14, but can be recessed to different extents in terms of amount and/or can be inclined relative to one another, for example to prevent the chain from being inclined around its lengthwise direction of the chain and thus an insertion opening located radially on the inside of the chain into an engagement space of an outer link chain link in order to incline the chain longitudinal direction towards the tooth crest of the catch tooth 44 or to incline the chain still engaged on the delivery tooth 38 around the chain longitudinal direction at the delivery tooth to the smaller Pinion 12 tend to be able to.

Starting from the catching tooth 44 there are five teeth clockwise between the catching tooth 44 and the output tooth 38 of the pinion 14, of which the middle one has a deflection surface 14d on its tooth surface pointing towards the smaller pinion 12. This has the same function as was previously described for the deflection surface 12d on the smaller sprocket 12.

Starting from the delivery tooth 38, there are seven teeth between the delivery tooth 38 and the catching tooth 44 of the pinion 14, which can be designed as conventional teeth 14a and 14b, with the teeth 14a being able to be designed thicker than the teeth 14b, advantageously with a thickness , which exceeds the clear width of the engagement space between two parallel inner plates of an inner plate chain link. The number of teeth located clockwise between the output tooth 38 and the catch tooth 44 of the pinion gear 14 is equal to the number of teeth of the pinion gear 14 minus 7.

In the rear view from the inside of the sprocket 14 in 3B one recognizes that the in 3A the output tooth 38 clockwise following thin tooth 14b ab on its smaller pinion 12 facing tooth surface has a recess surface 14e, which forms this special thin tooth 14b as a mobilizing tooth 14b' of an upshift process, which allows an inner plate chain link of a bicycle chain engaged by it more axial movement play than an ordinary thin tooth 14b.

Likewise one recognizes in 3B that the in 3A The thin tooth 14b adjacent to the catch tooth 44 in the counterclockwise direction has a recess surface 14f on its tooth surface facing away from the smaller sprocket 12, which forms this special thin tooth 14b as a mobilization tooth 14b" of a downshift process, which allows an inner plate chain link engaged by it more axial movement play than an ordinary thin tooth 14b.

The upshift mobilization tooth 14b' thus supports an upshift process through the movement play it allows for the bicycle chain. The downshift mobilizing tooth 14b" supports a downshift operation.

Starting from the delivery tooth 38 there are five teeth between the delivery tooth 38 and the catch tooth 44 of the pinion 14 .

The clockwise tooth adjacent to the catch tooth 44 of the pinion 14 again has a deflector surface 14h, which is delimited radially inward by a ramp 14c1 with a radially outward-pointing support surface for physical support of an inner plate of an inner-plate chain link when shifting down.

The tooth adjacent the output tooth 38 of the sprocket 14 in a counterclockwise direction has a deflector surface 14i which extends radially inwardly by a ramp 14c2 with a radially outwardly facing support surface for physically supporting an inner plate of an inner-plate chain link when shifting up from sprocket 12 to sprocket 14 is limited. Like the deflector surface 14h in the downshift region 40, the deflector surface 14i in the upshift region 34 allows passage of an inner-plate link but not an outer-plate link of the bicycle chain when shifting up onto the sprocket 14. The ramp 14c2 with its support surface pointing radially outward is preferably convex in shape corresponding to the concave shape of an inner link plate 54c in order to enable the inner link plate to bear as flatly as possible.

In the 4A and 4B the bicycle rear wheel sprocket pairing 15 with the sprockets 16 and 14 is shown in 4A in reference consideration and in 4B viewed from the opposite direction, i.e. from the inside. The sprocket 14 of the bicycle rear sprocket pair 15 is the sprocket 14 of the rear sprocket pair 13 previously discussed.

The same lower-case letters after the reference number 16 of the pinion 16 denote functionally identical components or component sections of the pinion 14 or the pinion 12, which are denoted there with the same lower-case letters.

Like the two pairs of rear wheel sprockets 11 and 13 above, the larger sprocket 16 of the pair of rear wheel sprockets 15 has only exactly one upshift area 34 with exactly one upshift depression formation 36 and exactly one release tooth 38 . Furthermore, the larger sprocket 16 has only exactly one downshift area 40 with exactly one downshift depression formation 42 and exactly one catch tooth 44 .

Starting from the catch tooth 44 there are five teeth between the catch tooth 44 and the output tooth 38 in a clockwise direction, the middle of the five teeth having a deflection surface 16d which has already been explained in connection with the pinions 12 and 14 previously described.

Starting from the delivery tooth 38 there are nine teeth between the delivery tooth 38 and the catching tooth 44 in a clockwise direction, which are formed alternately as thick teeth 16a and thin teeth 16b for clear orientation of the bicycle chain relative to the sprocket 16 in the circumferential direction. Thin tooth 16b' clockwise adjacent output tooth 38 is a mobilization tooth for an upshift to smaller sprocket 14. Thin tooth 16b'' counterclockwise adjacent catch tooth 44 is a mobilization tooth for downshifting from smaller sprocket 14 to larger sprocket 16 4B the corresponding recess surfaces 16e of the mobilization tooth 16b' and 16f of the mobilization tooth 16b" are shown.

The number of clockwise teeth between the output tooth 38 and the catch tooth 44 equals the number of teeth on the pinion gear 16 minus 7.

It is noteworthy that the tooth with the deflection surface 16h and with the support ramp 16c1 delimiting this deflection surface 16h is axially adjacent to the mobilization tooth 14b" of the sprocket 14 with a convex head surface 14cf, so that the chain can also be shifted down from the sprocket 14 to the sprocket 16 axially outwards past the deflection surface 16h inner-plate chain link 52 can be physically supported with its two inner plates on its radially inner edge 52c, the axially outer inner plate on the top surface 14cf and the axially inner inner plate on the ramp 16c1.

In 4C 1, a downshift of a bicycle chain 50 from the sprocket 14 to the larger sprocket 16 is shown for reference. The catch tooth 44 of the pinion 16 has already caught the chain 50, more precisely an outer link chain link 54 of the same. The next outer link chain link 54 in the driving direction of rotation is still in engagement with the pinion 14 . In the shifting path between the sprockets 14 and 16 there is only exactly one inner link chain link 52 which is not in engagement with any of the sprockets 14 and 16 during the shifting process.

4D shows the switching process of 4C in the opposite viewing direction, i.e. from the axial inside.

In 4E 1, an upshift of a bicycle chain 50 from the sprocket 16 to the larger sprocket 14 is shown for reference. The output tooth 38 of the sprocket 16 is still engaged with the chain 50, more specifically with an outer plate link 54 thereof. The next outer link chain link 54 counter to the direction of rotation of the drive is already engaged by a tooth of the pinion 14 . In the transfer path between the sprockets 16 and 14 there is only exactly one inner link chain link 52 which is not in engagement with any of the sprockets 14 and 16 during the shifting process.

4F shows the switching process of 4E in the opposite viewing direction, i.e. from the axial inside.

In the 5A and 5B is according to the previous ones 3A and 3B respectively. 4A and 4B the largest and last bicycle rear wheel sprocket pairing 17 according to the invention is shown, namely in 5A in reference consideration and in 5B viewed from the inside in the opposite axial direction.

Identical lower-case letters after the reference number 18 of the pinion 18 denote functionally identical components or component sections of the pinions 12, 14 or 16, which are denoted there with the same lower-case letters.

Like the previously discussed rear wheel sprocket pairs 11, 13 and 15, the rear wheel sprocket pair 17 on the larger sprocket 18 has only exactly one upshift area 34 with exactly one upshift depression formation 36 and with exactly one release tooth 38. The larger sprocket 18 also has exactly one downshift area 40 with exactly one downshift indentation 42 and with exactly one catch tooth 44 .

The larger sprocket 18 has only three teeth, which is particularly advantageous for the wear resistance of the sprocket 18 starting from the fang 44 clockwise between the fang 44 and the delivery tooth 38 . Starting from the delivery tooth 38, 13 teeth are present clockwise between the delivery tooth 38 and the catching tooth 44, which corresponds to the number of teeth of the pinion 18 minus 5.

Of the 13 teeth located clockwise between the delivery tooth 38 and the catching tooth 44, the teeth immediately adjacent to the delivery tooth 38 and the catching tooth 44 are designed as mobilization teeth 18b' and 18b" in the manner described above. The remaining teeth are for safe Guide of the chain on sprocket 18 during meshing in the manner described above formed as thick teeth 18a and thin teeth 18b.

Even when shifting down from the sprocket 16 to the sprocket 18, an inner link chain link with its two inner links can be supported once on the top face 16cf and once on the ramp 18c1. Clockwise in front of the catching tooth 44 of the pinion 18, the tooth gap 43 is enlarged radially inward in order to give the chain roller immediately ahead of the catching tooth 44 movement space radially inward when shifting down onto the pinion 18.

The previously described pinion pairs 11, 13, 15 and 17 can only shift up in the upshift range 36 from the respective larger sprocket to the respective axially adjacent next smaller sprocket. This means that on each larger sprocket of the sprocket pairings 11, 13, 15 and 17 mentioned, the chain is shifted from the larger sprocket to the next smaller sprocket at exactly one point, in such a way that the respective delivery tooth 38 is the last tooth of the larger sprocket, still engaged with the chain. Because of the drive direction of rotation D shown, chain links following the delivery tooth 38 slide counterclockwise laterally past the teeth adjacent to the delivery tooth 38 in the counterclockwise direction and thereby utilize the respective upshift depression formation 36 as a movement space.

Likewise, the chain can only be shifted from the smaller to the larger sprocket at one point on the specified sprocket pairs 11, 13, 15 and 17, and always only in such a way that the fang 44 of the larger sprocket is the first tooth of the larger sprocket, which engages between two plates, usually outer plates, of a chain link. The chain links adjacent to the fang tooth 44 in a clockwise direction approach the respective larger sprocket using the downshift depression formation 42, so that the Fang tooth 44 associated outer plate chain link can reach axially in the engagement area.

If the cyclist gives the shifting command in such a way that the relevant shifting tooth on the larger sprocket rotating clockwise: output tooth 38 or catching tooth 44, has just passed the shifting area on the rear wheel, the initiated shifting process takes place in the next sprocket revolution when the output tooth 38 or the catch tooth 44 returns to the angular range or shifting range relevant for the execution of a shifting process relative to the derailleur. The shift latency for both downshifting and upshifting on the sprocket pairs 11, 13, 15 and 17 is a maximum of one sprocket revolution, which is usually tolerated by cyclists. Experience has shown that higher switching latencies are no longer tolerated, but rather perceived as a malfunction.

The pinion 18 is the smallest of three pinions 18, 20 and 22 of a transition pinion group 19, which has the only odd-numbered pinion of the rear wheel cassette 1 with the pinion 20.

In 6 12, the smaller sprocket pairing of sprockets 20 and 18 of transition sprocket set 19 is shown for reference.

Identical lower-case letters after the reference number 20 of the pinion 20 denote functionally identical components or component sections of the pinions 12, 14, 16 or 18, which are denoted there with the same lower-case letters.

A problem with this is that each tooth of the even-numbered sprocket 18 is associated with the same type of chain link for engagement between the respective link plates of the respective chain link for the entire duration of the meshing engagement of the sprocket 18 with the bicycle chain.

On the odd-numbered sprocket 20 with 21 teeth, however, the type of chain link assigned to a tooth for positive engagement changes with each revolution. Nevertheless, the chain from the odd-numbered sprocket 20 should be transferred to the sprocket 18 in a defined manner with regard to the relative position of the chain link sequence both when shifting up and to the sprocket 22 in a defined manner when shifting down. On the even-numbered sprockets 20 and 22, chance should not decide whether a tooth engages with an outer link chain link or an inner link chain link, but rather a defined shifting of the chain should be ensured by appropriate design of the transition sprocket group 19.

For this purpose, the transition pinion 20 has three identical circumferential sections, each with seven teeth, which successively form the entire circumference of the transition pinion 20 . Again, each of the three circumferential sections has only exactly one dispensing tooth 38 and only exactly one catching tooth 44 . Likewise, each of the three circumferential sections has exactly one upshift area 34 with exactly one upshift depression formation 36 and only exactly one downshift area 40 with exactly one downshift depression formation 36 . The switching latency of the transition pinion 20 is very short due to the juxtaposition of the three circumferential sections. Between the catch tooth 44 and the output tooth 38 there are five teeth on the pinion 20 clockwise. Between two output teeth 38 or between two catch teeth 44 there are six teeth in the circumferential direction of the pinion 20 . Thus, if an inner plate undesirably approaches a fang 44 of sprocket 20 during a downshifting process from sprocket 18, for whatever reason, and the fang 44 does not positively engage with the bicycle chain, the counterclockwise next fang 44 of the Sprocket 20 approximates an outer plate and thus an outer plate chain link using the movement space provided by the downshift depression formation 42, which the catch tooth 44 can catch.

The upshift and the output tooth 38 of the pinion gear 20 are the same, mutatis mutandis. If an inner plate chain link is in positive engagement with the delivery tooth 38 immediately after the cyclist has initiated the upshifting process, the bicycle chain remains on the sprocket 20 until the next delivery tooth 38 is engaged with an outer plate chain link in a counterclockwise direction and the bicycle chain is then utilized of the space allowed for movement by the upshift indentation formation 36 can be allocated to the smaller sprocket 18.

The catching tooth 44 and the delivery tooth 38 are extremely advantageously arranged in such a way that when the three identical circumferential sections are lined up, the delivery tooth 38 and the catching tooth 44 are immediate neighbors. Since the teeth 38 and 44 are in any case specially designed as delivery teeth and catching teeth, and generally have a smaller thickness and a strong axial approximation to the adjacent smaller pinion 18, the teeth 38 and 44 act not only as delivery teeth 38 or catching teeth 44, but the delivery tooth 38 forms a mobilizing tooth 20b" for the canine tooth 44 and the canine tooth 44 forms a mobilization tooth 20b' for the delivery tooth 38.

Due to this dual function of delivery tooth 38 and fang tooth 44, each also as a mobilization tooth 20b" and 20b', despite the juxtaposition of three circumferential sections each with at least two modified and thus weakened teeth 38 and 44, no additional structural weakening of the teeth through the formation of separate mobilization teeth is required. which leads to a stable and wear-resistant transition pinion 20 overall.

In 7 12 shows the larger sprocket pairing of the transition sprocket set 19 with the 24T sprocket 22 and the 21T sprocket 20 for reference.

Here, too, it is important to transfer the bicycle chain from the odd-numbered sprocket 20 to the larger sprocket 22 with a clear relative arrangement of the chain link sequence.

Identical lower-case letters after the reference number 22 of the pinion 22 denote functionally identical components or component sections of the pinions 12, 14, 16, 18 or 20, which are denoted there with the same lower-case letters.

The 24-T sprocket 22 also has three identical circumferential sections that sequentially form the full circumference of the sprocket 22 in the circumferential direction. Each circumferential section therefore has eight teeth. In 7 For the sake of simplicity, only exactly one peripheral section of the pinion 22 is provided with reference symbols.

At the clockwise extreme of the circumferential portion is the mobilizing tooth 22b' for the counterclockwise adjacent delivery tooth 38.

Continuing counterclockwise, the output tooth 38 is followed by three teeth on which the upshift indentation 36 and the downshift indentation 42 are formed, with a deflector surface 22d being formed on the central tooth of the three teeth.

The three teeth are followed counterclockwise by the catch tooth 44, which in turn has its mobilization tooth 22b" adjacent counterclockwise. A regular tooth of the pinion 22 is located counterclockwise at the outermost end of the circumferential section, which, for example, is designed as a thick tooth 22a in such a way that it can only engage an outer plate link.

Although mobilization teeth 22b' and 22b" are formed here in addition to a delivery tooth 38 and a catching tooth 44, both depression formations 36 and 42 for downshifting and for upshifting are formed in a space of only three teeth, so that overall there is a moderate structural weakening Material reduction is realized on the pinion 22 and the pinion 22 has a high overall stability and wear resistance.The larger a pinion is, the less the formation of depression formations and the like are of importance as a structural weakening of the strength of the pinion.

Although, due to the unknown number of revolutions of the sprocket 20, it is unknown in which relative position with regard to the chain link sequence the bicycle chain is transferred from the sprocket 20 to the sprocket 22 when shifting down, that fang 44 which an outer plate chain link is brought close to, the chain through positive engagement with the Catch the chain link and thus ensure a downshift. At the latest, this is the second catch tooth 44, which arrives in a relevant shifting range relative to the derailleur causing the shifting process.

Likewise, the chain is transferred to the smaller sprocket 20 by only exactly one tooth per circumferential section of the sprocket 22, namely the delivery tooth 38 as the last meshing tooth. Since the output tooth 38 on the sprocket 22 is always assigned an outer link chain link, an upshifting process takes place from the sprocket 22 to the sprocket 20 on the next output tooth 38 passing the shifting range of the derailleur. This means a very short shifting latency of only one third of a revolution and, because of the design only one tooth as the delivery tooth 38 per circumferential section, the smallest possible weakening of the pinion 22.

The radially inner bottom of tooth space 43, which is immediately adjacent clockwise to fang 44, is radially closer to pinion axis R than the tooth bottoms of the remaining tooth spaces. Due to the radially inward path of movement thus granted for a chain roller, the shifting path that the bicycle chain takes when shifting from the smaller sprocket 20 to the larger sprocket 22 can be adjusted such that its length is an integer multiple of the chain pitch. This is a boundary condition for a shifting process between two sprockets.

Both inner plates of an inner plate chain link can also be supported on the pair of sprockets 19 when shifting up from sprocket 22 to sprocket 20, namely for the inner plate lying further axially on the outside on the head surface 20ci and for the inner plate lying further axially on the inside on the ramp 22c2, which delimits the deflection surface 22i radially inwards. The top surface 20 ci is to support a concave surface as possible inner edge 54c of an inner plate is convex, but the leading end of the head surface 20ci in the driving direction of rotation is arranged radially further outward than the trailing end of the head surface 20ci.

In 8th 1 shows an example of how a bicycle chain 50 is shifted up from a sequence of outer plate chain links 52 and inner plate chain links 54 from meshing engagement with the sprocket 22 to the smaller sprocket 20 . It can be seen that the output tooth 38 is the last tooth of the sprocket 22 that engages the bicycle chain 50 .

Only as an example is in 9 a sprocket pairing of the 28T sprocket 24 and the 24T sprocket 22 previously discussed is shown. The pinion 22 has already been discussed above. In principle, the pinion 24 has two upshift areas 34 and two downshift areas 40 along its circumference, with areas 34 and 40 shifting in the same direction lying diametrically opposite one another on the pinion 24 .

Identical lower-case letters after the reference number 24 of the pinion 24 denote functionally identical components or component sections of the pinions 12, 14, 16, 18, 20 or 22, which are denoted there with the same lower-case letters.

The pinion 24 also has tooth gaps 43 with a tooth base that is offset radially inward toward the pinion axis R. However, these tooth gaps 43 play no role in shifting the chain between the adjacent sprockets 24 and 22, but rather in shifting the bicycle chain between the sprocket 24 and the next larger sprocket 26.

In 10 the largest sprocket 32 is shown detached from the other sprockets 10 to 30 in relation to each other. The pinion 32 comprises a ring gear 60, an intermediate ring 62 and a radially inner wedge ring 64 for transmitting torque to a driver (not shown but readily known to those skilled in the art) or to an adapter arranged between the wedge ring 64 and the driver. The splined profile of the adapter or driver interacting with the radially inner profile of the splined ring 64 is designed to be complementary to the radially inner splined profile of the wedged ring 64 . Radially outer struts 66a and 66b connect the ring gear 60 to the intermediate ring 62 in a torque-transmitting manner. Radially inner struts 68 connect the intermediate ring to the wedge ring 64.

To avoid undesired bending deformation of the struts 66b and 68, these are arranged in such a way that their radially inner strut ends precede the radially outer ones in the direction of rotation D of the drive. The struts 66a are made wider in the circumferential direction than the struts 66b.

Attachment openings 70 indicate where the pinion dome of the integrally connected pinions 14 to 30 and the smaller pinion gears 12 and 10 screwed to the pinion dome is torque-transmittingly connected to the largest pinion 32 with fasteners such as pins, rivets, screws and the like.

The fastening holes 70 are on the one hand arranged radially as far outwards as possible, but without disturbing the engagement of the sprocket teeth with the bicycle chain, and on the other hand are formed in regions of the sprocket 32 which are as stable as possible. Therefore, the mounting holes 70 are primarily formed in the wider radially outer struts 66a and near the connection points of the intermediate ring 62 with the radially inner struts 68 .

In 10A 1 is a view of the largest sprocket 32 viewed orthogonally to the sprocket axis R. There it can be seen that the pinion 32 is offset outwards in the areas located radially closer to the pinion axis R, ie away from the longitudinal center plane LME. As a result, as little axial installation space as possible is required for accommodating the twelve-speed sprocket cassette 1 on the driver located radially inside the wedge ring 64 . In addition, the larger sprocket 32 is stiffened against bending moments which act on the largest sprocket 32 due to the chain skewing. The pinion 32 and the pinion dome connected to it reinforce each other.

The sprocket cassette 1 is designed in such a way that all the smaller sprockets 10 to 30 transmit their torque directly to the sprocket 32, which transmits the torque transmitted by the rider or the electric motor by means of the bicycle chain 50 to the sprocket cassette 1 via the aforementioned driver to the rear wheel hub.

As on the pointing to the longitudinal center plane LME side of the pinion 32, on which the viewer of the 1 OB looks, it can be seen that thick teeth 32a and thin teeth 32b are also formed on the largest sprocket 32 alternately in succession in the circumferential direction. The recesses on the tooth surfaces pointing in the axial direction for forming thin teeth 32b are formed exclusively on the side of the larger pinion 32 pointing away from the next smaller pinion 30 .

The same lower-case letters after the reference number 32 of the pinion 32 denote functionally identical components or component sections of the pinions 12, 14, 16, 18, 20, 22 or 24, which are denoted there with the same lower case letters.

In 10B Also shown is a formation of ramps on some dispensing teeth 38, on some canines 44, and on the mobilizing teeth 32b' and 32b'' adjacent the ramp-forming dispensing teeth 38 and canines 44. The ramps are identified by the reference numeral of the respective tooth and the lowercase letter g The ramps of the mobilization teeth are identified by the same apostrophes as the associated mobilization teeth.

The ramps 38g, 32g', 44g and 32g'' form a radial and axial step on the tooth surface of the associated teeth 38, 32b', 44 and 32b'' facing away from the next smaller pinion 30. The ramps 38g, 32g′, 44g and 32g″ form a ramp surface pointing radially outward, ie away from the pinion axis R, on which edge surfaces of the bicycle chain 50 pointing radially inward can be supported.

These ramps 38g, 32g', 44g and 32g'' stabilize the chain 50 in a special way when it meshes with the largest sprocket 32.

When pedaling backwards using the freewheel that is usually present on the rear wheel hub, the skew of the chain can, under certain circumstances, have a stabilizing effect on the meshing engagement of the sprocket 32 with the bicycle chain 50 . Since in particular the delivery teeth 38 and the mobilization teeth 32b' adjacent to them, due to their design, support a shifting of the chain to the next smaller sprocket 30 towards which the skewing acts, above all a ramp is formed there. Ramps are also formed on the shift-relevant teeth of a downshift area, ie on the catching tooth 44 and its mobilization tooth 32b", in order to stabilize the chain 50.

The ramps mentioned not only hold the chain even in the event of a very unfavorable effect of the chain skew to the front chainring on the sprocket 32, but also support the shifting of the chain 50 down to the larger sprocket 32 or up from the larger sprocket 32 to the next smaller sprocket 30 The ramps make it possible for the chain to be held stably and with physical guidance even in a radially further outward position on the pinion 32 in the areas relevant to shifting: upshifting area 34 and downshifting area 40 than is the case with conventional tooth meshing in which the catching tooth 44, the delivery tooth 38 or the mobilizing teeth 32b" and 32b' adjacent to them engage radially completely in the interstices of the chain links.

Thus, the ramps stabilize the chain 50 against chain skewing toward the front sprocket when the derailleur chain guide roller is aligned coplanar with the sprocket 32 to hold the chain on the larger sprocket 32 and chain skewing acts against chain 50 holding on the sprocket 32. Further, the ramps assist in shifting the chain 50 when the derailleur chain guide pulley is coplanar with the future chain-leading sprocket while the chain 50 is still engaged on the current chain-leading sprocket.

The ramps shown can also be formed on the sprockets 30, 28, 26, etc., preferably on the side of the respective sprocket pointing away from the next smaller sprocket. However, since the chain skewing decreases in terms of amount towards the medium-sized sprockets of the sprocket cassette 1, the ramps are particularly important on the larger sprockets 32, 30 and also 28.

In 11 a bicycle provided with a sprocket cassette 1 according to the invention is shown in a roughly schematic manner and is generally denoted by 70 . A front wheel 72 and a rear wheel 74 are attached to a bicycle frame 76 around the respective plane of the drawing 11 orthogonal wheel axles rotatably mounted. The front wheel 72 can be connected to the bicycle frame 76 via a suspension fork 78 . The rear wheel 74 can also be connected to the bicycle frame 76 via a spring-loaded suspension 80 .

The rear wheel 74 is connected via a drive assembly 82 comprising a single front sprocket 24 and mounted only in 1 Roughly schematically represented bicycle rear sprocket cassette 1, drivable. The drive torque can be transmitted via pedal cranks 88 and a pedal crank shaft 88a connected thereto to the front chainring 84 and from there by means of the bicycle chain 50 via the sprocket cassette 126 to the rear wheel 74. To support a cyclist driving the pedal cranks 88 with muscle power, a supporting electric motor 90 can be arranged on the bicycle frame 76 in such a way that it also transmits its supporting drive torque via the pedal crank shaft 88a to the front chain ring 84 . A gear, in particular a planetary gear, can be provided between the pedal crankshaft 88a and the chain wheel 84 . The transmission ratio of the gearbox must be taken into account when calculating the effective number of teeth of the 84 chainring. The actual number of teeth of the chain ring 84 is to be multiplied by the factor with which the gearing is inserted into it transmitted torque to its output side. An increase in the torque through the transmission thus leads to an increased effective number of teeth on the chainring 84 compared to the actual number of teeth, and vice versa.

A battery 92 as an energy store for the supporting electric motor 90 can be provided in or on the frame 76 .

The bicycle chain 50 can be brought into meshing engagement with a sprocket to be selected by the rider from the plurality of sprockets 10 to 32 of the sprocket cassette 1 for torque transmission to the rear wheel 74 by a rear derailleur 94 in a manner known per se. The derailleur 94 has a chain guide roller 96 closest to the sprocket cassette 1 and a tension roller 98 .

Both the muscular torque of the cyclist and the supporting torque of the electric motor 90 are transmitted to the rear wheel 74 via the rear wheel sprocket cassette 1 in the example of a bicycle 70 . The electric motor 90 thus has the effect as if the cyclist could retrieve a pedal power increased by the support power of the electric motor 90 .

Since the bicycle 70 shown as an example has exactly one front chainring 84 , the entire gear range of the bicycle 70 is realized by the sprocket cassette 1 .

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• EP 1188658 B1 [0002, 0015]

Claims (23)

Bicycle rear wheel sprocket pair (11, 13, 15, 17) for force-transmitting engagement with a bicycle roller chain (50), the rear wheel sprocket pair (11, 13, 15, 17) being rotatable about a sprocket axis (R), the sprocket axis (R ) defines an axial direction running along the pinion axis (R), a radial direction running orthogonally to the pinion axis (R) and a circumferential direction running around the pinion axis (R), the rear wheel pinion pair (11, 13, 15, 17) having a larger pinion ( 12, 14, 16, 18) and a smaller pinion (10, 12, 14) which is coaxial and axially directly adjacent to the larger pinion (12, 14, 16, 18). , 16), wherein the larger sprocket (12, 14, 16, 18) has an even number of teeth equal to or less than 22 teeth and wherein the difference in the number of teeth between the larger and the smaller sprocket (10, 12, 14, 16) is exactly two teeth is, where i) the larger sprocket (12, 14, 16, 18) has an upshift area (34) with an upshift indentation (36) along a portion of its circumference on its end face facing the smaller sprocket (10, 12, 14, 16). , wherein the shift-up area (34) is designed and arranged on the clockwise - when viewed axially of the pair of rear wheel sprockets (11, 13, 15, 17) in a reference state in which the smaller sprocket (10, 12, 14, 16) closer to the observer than the larger sprocket (12, 14, 16, 18) - rear wheel sprocket pair (11, 13, 15, 17) rotating about the sprocket axis (R) causes a change of engagement of the bicycle roller chain (50) from the larger to the smaller sprocket (10, 12, 14, 16), wherein on the larger sprocket (12, 14, 16, 18) the upshift recess formation (36) is assigned exactly one delivery tooth (38), which is designed to do so by its shape and orientation is, in cooperation with the face-side upshift depression for mation (36) during an upshifting process from the larger sprocket (12, 14, 16, 18) to the smaller sprocket (10, 12, 14, 16) to be the last tooth between a pair of link plates of a chain link (52) of the bicycle Roller chain (50) engages, and/or ii) the larger sprocket (12, 14, 16, 18) has a shift-down area (40) with a shift-down depression formation (42) along its circumference on its end face pointing towards the smaller sprocket (10, 12, 14, 16), wherein the shift-down area (40) is designed to perform a mesh change on the rear wheel pinion pair (11, 13, 15, 17) rotating clockwise about the pinion axis (R) when the rear wheel pinion pair (11, 13, 15, 17) is viewed axially in the reference state of the bicycle roller chain (50) from the smaller to the larger sprocket (12, 14, 16, 18), with only exactly one catching tooth (44 ) which, due to its shape and orientation, is designed to interact with the front downshift indentation (42) during a downshift from the smaller sprocket (10, 12, 14, 16) to the larger sprocket (12, 14, 16 , 18) the first tooth to be which engages between tabs of a chain link of the bicycle roller chain (50). Bicycle rear wheel sprocket pairing (11, 13, 15, 17). claim 1 characterized in that the output tooth (38) immediately follows the upshift indentation (36) in a clockwise direction. Bicycle rear wheel sprocket pairing (11, 13, 15, 17). claim 1 or 2 , characterized in that the larger sprocket (12, 14, 16, 18) has exactly one upshift area (34) with an upshift indentation formation (36) and exactly one output tooth (38) along its entire circumference. A bicycle rear sprocket pair (11,13,15,17) as claimed in any one of the preceding claims characterized in that the counterclockwise fang (44) immediately follows the downshift indentation (42). Bicycle rear wheel sprocket pairing (11, 13, 15, 17) according to one of the preceding claims, characterized in that the larger sprocket (12, 14, 16, 18) has exactly one downshift area (40) and exactly one catching tooth (44) along its entire circumference. having. Bicycle rear wheel sprocket pairing (11, 13, 15, 17) according to one of the preceding claims, characterized in that clockwise - when viewing the rear wheel sprocket pairing (11, 13, 15, 17) in the reference state - between the output tooth (38) and the Fangzahn (44) k teeth are located, not counting the delivery tooth (38) and the fang tooth (44), and where k = T - d applies, where T is the number of teeth of the larger sprocket (12, 14, 16, 18) and where d is equal to 5 or equal to 7. Bicycle rear wheel sprocket pairing (11, 13, 15, 17). claim 6 , characterized in that when T is an integer evenly divisible by 6, d equals 5, and when T is not an integer evenly divisible by 6, d equals 7. Bicycle rear wheel sprocket pairing (11, 13, 15, 17) according to one of the preceding claims, characterized in that in a clockwise direction - when viewed axially of the rear wheel sprocket pairing (11, 13, 15, 17) in the reference state - there are n teeth located between the fang (44) and the delivery tooth (38), not counting the fang (44) and the delivery tooth (38), where n equals 3 or is equal to 5. Bicycle rear wheel sprocket pairing (11, 13, 15, 17). claim 8 , characterized in that when the number of teeth on the larger pinion (12, 14, 16, 18) is an integer divisible by 6 without remainder, n is equal to 3, and when the number of teeth on the larger pinion (12, 14, 16 , 18) is not an integer divisible by 6 without remainder, n is equal to 5. Bicycle rear wheel sprocket pairing (11, 13, 15, 17) according to one of the preceding claims, characterized in that the tooth side pointing away from the smaller sprocket (10, 12, 14, 16) of the tooth (12b ', 14b', 16b', 18b') is located closer to the smaller pinion (10, 12, 14, 16) than the tooth surface of the tooth (12b') pointing away from the smaller pinion (10, 12, 14, 16), 14b', 16b', 18b') clockwise after the next tooth, and/or that the tooth side pointing away from the smaller pinion (10, 12, 14, 16) of the tooth (12b", 14b ", 16b", 18b") is located closer to the smaller pinion (10, 12, 14, 16) than the tooth surface of the tooth (12b", 14b") pointing away from the smaller pinion (10, 12, 14, 16). 16b", 18b") in an anti-clockwise direction of the next but one tooth. Bicycle rear wheel sprocket pairing (11, 13, 15, 17) according to one of the preceding claims, characterized in that the larger sprocket (12, 14, 16, 18) and / or the smaller sprocket (10, 12, 14, 16) at least each having a thinner tooth (10b, 12b, 14b, 16b, 18b) and a thicker tooth (10a, 12a, 14a, 16a, 18a) alternately along a circumferential section in the circumferential direction. Bicycle rear wheel sprocket cassette (1) with a plurality of sprockets (10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32), each with a different number of teeth, connected for common non-slip rotation about the sprocket axis (R). , wherein the bicycle rear sprocket cassette (1) contains at least one bicycle rear sprocket pair (11, 13, 15, 17) according to any one of the preceding claims. Bicycle rear sprocket cassette (1). claim 12 , characterized in that the bicycle rear wheel sprocket cassette (1) has at least three sprockets (12, 14, 16) each with a different number of teeth, which two bicycle rear wheel sprocket pairings (11, 13, 15, 17) according to one of Claims 1 until 11 belong, the pinion (12, 14, 16) with the average number of teeth being the larger pinion (12, 14, 16) of one rear wheel pinion pair (11, 13, 15) and the smaller pinion (12, 14, 16) of the other rear wheel pinion pair (13, 15, 17) is. Bicycle rear sprocket cassette (1). claim 12 or 13 , characterized in that all sprockets of the rear wheel sprocket cassette (1) with a number of teeth of 20 or less bicycle rear wheel sprocket pairings (11, 13, 15, 17) according to one of Claims 1 until 11 form. Bicycle rear sprocket cassette (1) according to one of Claims 12 until 14 characterized in that the rear sprocket cassette (1) has a transition sprocket group (19) comprising a 21T sprocket (20) with 21 teeth which is immediately adjacent to a smaller 18T sprocket (18) with 18 teeth . Bicycle rear sprocket cassette (1). claim 15 , characterized in that i) the 21-T sprocket (20) has at least two shift-up areas (34), each with a shift-up depression formation (36) wherein each upshift portion (34) is constructed and arranged to clockwise when viewed axially of the transition sprocket assembly (19) in a reference condition in which the 18-T sprocket (18) is closer to the viewer than the 21-T sprocket (20) (21) - the transition sprocket group (19) rotating around the sprocket axis (R), a mesh change of the bicycle roller chain (50) from the 21-T sprocket (20) to the 18-T sprocket (18), wherein on the 21-T sprocket (20) each of the two shift-up depression formations (36) is assigned exactly one delivery tooth (38), which is designed by its shape and orientation to interact with the its associated frontal upshift depression formation (36) during of an upshift from the 21T sprocket (20) to the 18T sprocket (18) to be the last tooth to engage between a pair of link plates (52) of the bicycle roller chain (50), with between the output teeth ( 38) an even number of teeth are located from circumferentially adjacent upshift indentations (36), not counting the output teeth (38) of adjacent upshift indentations (36), or/and ii) the 21-T sprocket ( 20) has at least two shift-down areas (40) along its circumference, each with a shift-down recess formation (42), in its end face pointing towards the 18-T sprocket (18), each shift-down area (40) being designed for this purpose on the clockwise - Rotating about the pinion axis (R) when viewed axially of the transition pinion group (19) in the reference state Transition sprocket group (19) to allow a change of engagement of the bicycle roller chain (50) from the 18T sprocket (18) to the 21T sprocket (20), with the 21T sprocket (20) of each downshift well formation (42) is assigned only exactly one catch tooth (44) which, due to its shape and orientation, is designed to interact with the shift-down recess formation (42) assigned to it on the face side during a shift-down process from the 18-T sprocket (18). the 21-T sprocket (20) being the first tooth to engage between lugs of a link (52) of the bicycle roller chain (50), with between the fangs (44) of circumferentially adjacent downshift indentations (42) a even number of teeth, not counting the fangs (44) of adjacent downshift indentations (42). Bicycle rear sprocket cassette (1). Claim 16 , characterized in that the 21-T sprocket (20) i) has exactly three upshift areas (34), each with an upshift depression formation (36) and each with exactly one output tooth (38), with between the output teeth (38) of in Circumferentially adjacent upshift depression formations (36) are located six teeth, not including the delivery teeth (38) of the adjacent upshift depression formations (36), or/and ii) exactly three downshift areas (40), each with a downshift depression formation ( 42) and each having exactly one fang tooth (44), with six teeth each being located between the fang teeth (44) of circumferentially adjacent shift-down depression formations (42), the fang teeth (44) of the adjacent shift-down depression formations (42) not are to be counted. Bicycle rear sprocket cassette (1). Claim 16 or 17 , characterized in that the transition sprocket group (19) additionally comprises a 24-T sprocket (22) with 24 teeth, the 21-T sprocket (20) being located axially between the 24-T sprocket and the 18-T - Pinion (18) is arranged. Bicycle rear sprocket cassette (1). claim 15 , characterized in that i) the 24-T sprocket (22) has at least two shift-up areas (34), each with a shift-up depression formation (36) wherein each upshift portion (34) is constructed and arranged to clockwise when viewed axially of the transition sprocket assembly (19) in a reference condition in which the 21-T sprocket (20) is closer to the viewer than the 24-T sprocket (22) - the transition sprocket group (19) rotating around the sprocket axis (R) a change of engagement of the bicycle roller chain (50) from the 24-T sprocket (22) to the 21-T sprocket (20) on the 24-T sprocket (22), each of the two shift-up depression formations (36) being assigned exactly one delivery tooth (38), which is designed to do so through its shape and orientation, in cooperation with the end face assigned to it Upshift pit formation (36) during a s upshifting process from the 24-T sprocket (22) to the 21-T sprocket (20) to be the last tooth that engages between a pair of link plates (52) of the bicycle roller chain (50), with the output teeth ( 38) an odd number of teeth are located on circumferentially adjacent upshift indentations (36), not counting the output teeth (38) of adjacent upshift indentations (36), or/and ii) the 24-pinion gear (24) in its end face pointing towards the 21-T sprocket (20), has at least two shift-down areas (40) along its circumference, each with a shift-down recess formation (42), each shift-down area (40) being designed to, on the clockwise - at axial view of the transition sprocket group (19) in the reference state - the transition sprocket group (19) rotating about the sprocket axis (R) a mesh change of the bicycle roller chain (50) from the 21-T sprocket (20) to the 24-T sprocket ( 24) to allow w although on the 24-T sprocket (24) each shift-down recess formation (42) is assigned exactly one catching tooth (44), which, due to its shape and orientation, is designed to interact with the shift-down recess formation (42 ) during a downshift from the 21T sprocket (20) to the 24T sprocket (22) to be the first tooth to engage between lugs of a link (52) of the bicycle roller chain (50), wherein between the fangs (44) an odd number of teeth are located from circumferentially adjacent downshift depression formations (42), not counting the fang teeth (44) of the adjacent downshift depression formations (42). Bicycle rear sprocket cassette (1). claim 19 , characterized in that the 24-T sprocket (22) i) has exactly three upshift areas (34), each with an upshift depression formation (36) and each with exactly one output tooth (38), with between the output teeth (38) of in Circumferentially adjacent shift-up depression formations (36) each have seven teeth, not counting the delivery teeth (38) of the adjacent shift-up depression formations (36), and/or ii) has exactly three shift-down areas (40), each with one shift-down depression formation (42) and one catch tooth (44) each, seven teeth each being located between the catch teeth (44) of circumferentially adjacent down-shift depression formations (42), not counting the fangs (44) of adjacent downshift depression formations (42). Bicycle rear sprocket cassette (1) according to one of Claims 12 until 20 , characterized in that the bicycle rear wheel sprocket cassette (1) is a twelve-speed sprocket cassette (1) with the following number of teeth gradation: 10 - 12 - 14-16-18-21 -24-28-32-38-44-52. A bicycle drive assembly comprising a bicycle rear sprocket pair (11, 13, 15, 17) according to any one of Claims 1 until 11 or a bicycle rear sprocket cassette (1) according to one of Claims 12 until 21 , with a meshing, force-transmitting engagement with the sprockets (10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32) of the bicycle rear wheel sprocket pair (11, 13, 15, 17) or The bicycle roller chain (50) formed in the bicycle rear wheel sprocket cassette (1), the bicycle roller chain (50) having a plurality of chain rollers which follow one another at a pitch and which are connected to one another by pairs of parallel link plates, the bicycle roller chain ( 50) has inner plate pairs with a smaller plate spacing and outer plate pairs with a larger plate spacing alternating in the direction of chain circulation. Bicycle drive assembly Claim 22 , characterized in that for at least one bicycle rear wheel sprocket pair (11, 13, 15, 17) it applies that during a shifting operation in which the bicycle roller chain (50) is driven by a sprocket (10, 12, 14, 16, 18) is shifted onto a pinion (10, 12, 14, 16, 18) axially adjacent thereto, between the last chain link (52) which is in engagement with the pinion (10, 12, 14, 16, 18) still guiding the chain, and the first chain link (52), which comes or is in engagement with the future chain-guiding sprocket (10, 12, 14, 16, 18), there is exactly one inner link chain link.

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