JP4836722B2 - Bicycle multi-speed transmission - Google Patents

Description

  The present invention relates to a bicycle multi-stage transmission in which a chain is bridged between a multi-stage drive sprocket and a multi-stage driven sprocket.

  A bicycle equipped with this type of multi-stage transmission has a multi-stage drive sprocket on the crankshaft and a multi-stage driven sprocket on the rear axle, and a chain is wound around each of the front multi-stage drive sprocket and the rear multi-stage driven sprocket. The drive sprocket to be applied is selected by the front derailleur, the driven sprocket is selected by the rear derailleur, and one shift stage is formed by the combination of the selected drive sprocket and driven sprocket.

  There are several combinations of drive sprockets and driven sprockets with almost the same gear ratio, and if the front derailleur and rear derailleur are operated by different operation means, it is not easy to shift up and down continuously. In addition, it is not easy to select a combination of a drive sprocket and a driven sprocket that obtains a desired gear ratio.

  In view of this, an example of electronic control (see, for example, Patent Document 1) has been proposed in which the front derailleur and the rear derailleur are each driven by a motor, and a transmission control unit that drives and controls both motors is provided.

JP 2003-185008 A

  The transmission control unit disclosed in Patent Document 1 moves between multi-stage drive sprockets until a combination of a drive sprocket and a driven sprocket at a target shift stage when a shift signal from a shift-up switch and a shift-down switch is input. Control is performed so that the sum of the amount and the amount of movement between the multistage driven sprockets becomes as small as possible, so that the speed change operation of the driver is simplified, and the desired speed ratio can be easily set.

  However, it requires two motors for driving the front derailleur and the rear derailleur and a transmission control unit for driving and controlling both motors, as well as a power supply for these electronic components, which greatly increases the cost and weight. The control configuration is also complicated.

  In addition, when replacing the mechanical speed change mechanism provided in a conventional bicycle with this electronic speed change mechanism, the speed change operation element of the mechanical speed change mechanism cannot be used. It must be done and becomes more expensive.

  SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and an object thereof is a mechanical inexpensive multi-stage transmission that can be easily set to a desired speed ratio regardless of a simple speed change operation and a simple mechanical configuration. It is in the point to offer.

In order to achieve the above object, according to the first aspect of the present invention, the front derailleur and the rear derailleur are driven by the operation of the speed changer supported by the vehicle body frame, and the chain is mounted from the multistage drive sprocket by the driving of the front derailleur. In a multi-stage transmission for a bicycle in which a drive sprocket to be delivered is selected, and a driven sprocket from which a chain is passed over from a multi-stage driven sprocket is selected by driving the rear derailleur and a transmission ratio is set. There is provided a mechanical distributor that distributes the output to two outputs, one output drives the front derailleur via a front output cable, and the other output drives the rear derailleur via a rear output cable. vessel is predetermined and out to the outer peripheral surface of the drum which rotates A shift drum cam groove of each predetermined shape is formed two rows based on the relationship, the shift drum is rotated in the rotational angle position corresponding to the input displacement of the shifting operation member, the cams of the shift drum The cable end of the front output cable and the cable end of the rear output cable are slidably fitted in the groove, respectively, and the input displacement of the speed change operator is caused by the rotation of the shift drum. The multi-stage transmission of the bicycle is converted into an output displacement in the direction of the drum rotation center axis of the rear output cable while being converted into an output displacement in the direction of the drum rotation center axis .

The invention according to claim 2 is the bicycle multi-stage transmission according to claim 1 , wherein the shift drum of the distributor is covered by a shift case fixed to a vehicle body frame, and the outer peripheral surface of the shift drum of the shift case. A straight groove directed in the direction of the central axis of the drum rotation is formed on the inner peripheral surface facing the front end, and the cable end of the front output cable straddles both the one cam groove of the shift drum and the straight groove of the shift case. The rear end of the rear output cable is slidably fitted across the other cam groove of the shift drum and the straight groove of the shift case. .

  According to the bicycle multi-stage transmission according to claim 1, the mechanical distributor that distributes one input to two outputs is configured so that the input displacement of the shift operator is determined based on a predetermined input / output relationship. Since the front derailleur is driven by converting the output displacement into the output displacement of the rear output cable and the rear derailleur is driven by converting the input displacement of the speed change operator into the output displacement of the rear output cable based on a predetermined input / output relationship. The two mechanical distributors simultaneously convert one operation input of the shift operator into the appropriate front output cable output displacement and rear output cable output displacement to drive the front derailleur and rear derailleur, respectively. The gear ratio can be easily realized.

The speed change operation is simple, the mechanical configuration is simple, and the cost can be reduced.
When the mechanical transmission mechanism provided in the conventional bicycle is replaced with the present multi-stage transmission, the transmission operator can be used as it is without replacement, and the replacement cost can be reduced.

  The distributor includes a shift drum in which two cam grooves each having a predetermined shape are formed on the outer peripheral surface of the rotating drum, and the shift drum rotates to a rotation angle position corresponding to the input displacement of the transmission operator. The cable end of the front output cable and the cable end of the rear output cable are slidably fitted in each cam groove of the shift drum, respectively, and the input displacement of the shift operation element is caused by the rotation of the shift drum. Therefore, a desired gear ratio can be easily realized by a simple shift drum cam mechanism.

According to the multistage transmission for a bicycle according to claim 2 , the shift drum is covered with a shift case fixed to the vehicle body frame, and the drum rotation center is formed on the inner peripheral surface of the shift case facing the outer peripheral surface of the shift drum. A straight groove oriented in the axial direction is formed, and the cable end of the front output cable is slidably fitted across both the cam groove of the shift drum and the straight groove of the shift case, and the cable end of the rear output cable Is slidably fitted across both the other cam groove of the shift drum and the straight groove of the shift case, so that each cable end of the front output cable and the rear output cable can be reliably and smoothly moved, The distributor can be reduced in size.

Hereinafter, an embodiment according to the present invention will be described with reference to FIGS.
FIG. 1 shows an overall perspective view of a bicycle 1 to which the multi-stage transmission 30 according to the present embodiment is applied.

  The body frame 2 of the bicycle 1 has a top tube 4 extending substantially horizontally behind the head tube 3 and a down tube 5 extending obliquely downward. The rear end of the top tube 4 and the lower end of the down tube 5 are seated. The tube 6 is connected, the top tube 4, the down tube 5, and the seat tube 6 form a triangle, and the seat stay 7 extends obliquely downward and rearward from the upper end of the seat tube 6. The chain stay 8 is branched bifurcated left and right from the lower end of 6 and the chain stay 8 extends rearward, and the lower end of the seat stay 7 and the rear end of the chain stay 8 are joined.

A front fork 10 extends downward from the head tube 3 and a front wheel 15 is pivotally supported at the lower end thereof.
A steering shaft 11 integrated with the front fork 10 extends upward, and a handle bar 12 is attached to a bent portion 11a forward of the upper end thereof so as to extend left and right.
The left and right ends of the handle bar 12 are grips 13 and 13.
A seat 17 is provided at the upper end of a seat shaft 16 that is fitted in the seat tube 6 so as to be extendable.

A rear axle 21 of the rear wheel 20 is rotatably supported at a joint portion between the lower end of the seat stay 7 and the rear end of the chain stay 8.
A crankshaft 22 is pivotally supported at the connecting portion between the down tube 5 and the seat tube 6 at the front end of the chain stay 8, and pedal arms 23, 23 are fitted to the left and right ends of the crankshaft 22, and the ends of the pedal arms 23, 23 are attached. Pedals 24, 24 are provided.

A three-stage drive sprocket group 31G having different diameters (the number of teeth) is integrally fitted to the crankshaft 22.
On the other hand, on the rear axle 21, a seven-stage driven sprocket group 32G having different diameters (number of teeth) is integrally fitted.

  A chain 33 is bridged between one drive sprocket 31 in the front three-stage drive sprocket group 31G and one driven sprocket 32 in the rear seven-stage driven sprocket group 32G, and the pedal force applied to the pedal 24 of the rider Is transmitted to the rear wheel 20.

A front derailleur 35 is provided in the vicinity of the three-stage drive sprocket group 31G, and the front derailleur 35 operates to select the drive sprocket 31 around which the chain 33 is wound from the three-stage drive sprocket group 31G and wind the chain 33 around. To do.
Further, a rear derailleur 37 is provided in the vicinity of the seven-stage driven sprocket group 32G, and the rear derailleur 37 selects the driven sprocket 32 around which the chain 33 is wound from the seven-stage driven sprocket group 32G and winds the chain 33 around it. Operates as follows.

A front output cable 36 extends from the front derailleur 35. The front output cable 36 is an inner cable that moves in the outer cable 36a. The front derailleur 35 is driven by the movement of the front output cable 36. .
Similarly, a rear output cable 38 extends from the rear derailleur 37. The rear output cable 38 is an inner cable that moves in the outer cable 38a, and the rear derailleur 37 is moved by the movement of the rear output cable 38. Driven.
The front derailleur 35 and the rear derailleur 36 are existing ones.

In this multi-stage transmission 30, a shift operation lever 40 is swingably provided at the upper end of the steering shaft 11, and an input cable 41 extending from the shift operation lever 40 is an inner cable that moves in the outer cable 41a. Therefore, the shift operation lever 40 is moved by swinging.
Note that a detent mechanism is incorporated in the speed change operation lever 40, and the swing angle is set to a predetermined angle step by step.

  In the multi-stage transmission 30, a distributor 50 is attached around the center of the top tube 4. The input cable 41 extends from the front of the distributor 50, and the front of the distributor 50 from the rear of the distributor 50. An output cable 36 and a rear output cable 38 extend rearward.

The structure of the distributor 50 will be described with reference to FIGS.
The distributor 50 has a structure in which a shift drum 61 is accommodated and pivotally supported in a shift case 51 having a bottom wall 53 at one end of a cylindrical portion 52 and closing the other end opening with a lid member 54. (See FIG. 2).

  As shown in FIG. 3, the cylindrical portion 52 of the shift case 51 includes a U-shaped curved portion 52 a whose section is curved in a U-shape and a flat plate portion 52 b that closes the opening thereof, and the U-shaped curved portion 52 a is about a half. The shift case 51 is fastened to the top tube 4 by a fixing band 25 and attached to the top tube 4 so that the flat plate portion 52b side is exposed.

  The shift drum 61 is composed of a cylindrical drum body 62 and a shaft 63 having one end reduced in diameter, and a cam groove having a shape that forms a predetermined input / output relationship on the outer peripheral surface of the drum body 62. 62F and 62R are formed side by side in the two-axis direction.

A small-diameter cylindrical bearing portion 53a protrudes from the inner surface of the bottom wall 53 of the shift case 51, and the tip of the shaft portion 63 of the shift drum 61 is pivotally supported via the bearing 58 on the bearing portion 53a.
On the other hand, a large-diameter cylindrical bearing portion 54 a is formed on the inner surface of the lid member 54, and the end portion of the drum body 62 of the shift drum 61 is pivotally supported via the bearing 59 on the bearing portion 54 a.
Therefore, the shift drum 61 is rotatably supported in the shift case 51.

  A flange 64 protrudes from a base portion of the shaft portion 63 of the shift drum 61 with respect to the drum body portion 62, a cable winding groove 65 is formed in the circumferential direction between the drum body portion 62, and one of the flanges 64. A cable locking hole 64b is formed at the part bulged (see FIG. 3).

Further, a spring locking portion 64a is formed on a part of the flange 64 of the shaft portion 63, and both ends are respectively connected to the spring locking portion 53a and the spring locking portion 64a formed on the inner surface of the bottom wall 53 of the shift case 51. The coil spring 66 is locked and wound around the shaft portion 63 so as to be interposed.
The shift drum 61 is urged by the coil spring 66 with respect to the shift case 51 in one rotation direction (the arrow direction in FIG. 3).

  The input cable 41 extending from the speed change operation lever 40 is inserted into the other end of the outer cable 41a through a grommet 67 at an axial position where the cable winding groove 65 is located in the U-shaped curved portion 52a of the shift case 51. The input cable 41 moving in the outer cable 41a extends into the shift case 51 and is wound in the cable winding groove 65, and the locking portion 41b at the tip of the input cable 41 is locked in the cable locking hole 64b of the flange 64. Is done.

The winding direction of the input cable 41 into the cable winding groove 65 is a direction in which the shift drum 61 is rotated against the urging force of the coil spring 66 when the input cable 41 is pulled.
When the input cable 41 is moved by operating the speed change lever 40, the shift drum 61 is set to a required rotation angle by the urging force of the coil spring 66.

Linear grooves 56F and 56R are parallel to the drum rotation center axis of the shift drum 61 by guide rails 55f and 55r that are paired with two connecting corners of the U-shaped curved portion 52a and the flat plate portion 52b of the shift case 51, respectively. Is formed.
The two linear grooves 56F and 56R are at an opening angle position of 90 degrees with respect to the drum rotation center axis.

  Cable fitting holes 54b and 54c are formed in portions corresponding to the linear grooves 56F and 56R in the lid member 54 of the shift case 51, respectively, and the outer cable 36a of the front output cable 36 is formed in each of the two cable fitting holes 54b and 54c. One end of the outer cable 38a of the rear output cable 38 is fitted through grommets 68 and 69.

A cubic cable end 36b at the front end of the front output cable 36 extending from the outer cable 36a into the shift case 51 extends over both the straight groove 56F and one cam groove 62F of the shift drum 61. It fits freely.
Similarly, a cubic cable end 38b at the tip of the rear output cable 38 extending from the outer cable 38a into the shift case 51 extends over both the straight groove 56R and the other cam groove 62R of the shift drum 61. It is slidably fitted.

  Therefore, when the shift drum 61 is rotated via the input cable 41 by the operation of the speed change operation lever 40, the cable end 36b is guided in the one cam groove 62F and moved in the axial direction along the straight groove 56F. The front output cable 36 integrated with the end 36b is displaced in the drum rotation center axis direction, guided by the other cam groove 62R, and the cable end 38b moves in the axial direction along the straight groove 56R. The integrated rear output cable 38 is displaced in the direction of the drum rotation center axis.

  That is, the distributor 50 changes the input displacement of the input cable 41 due to the operation of the speed change operation lever 40 by means of the two cam grooves 62F and 62R of the shift drum 61 to rotate the drums of the front output cable 36 and the rear output cable 38, respectively. Simultaneously convert to output displacement in the direction of the dynamic center axis.

FIG. 5 is a diagram in which cam grooves 62F and 62R on the peripheral surface of the shift drum 61 are developed on a plane.
The cam groove 62F for displacing the front output cable 36 (cable end 36b) has three displacement positions (1, 2, 3) in the drum rotation central axis direction corresponding to the 3 stage drive sprocket group 31G. The cam groove 62R for displacing the rear output inner cable 38 (cable end 38b) has seven displacement positions (1, 2, 3, 4, 5 in the drum rotation central axis direction corresponding to the seven-stage driven sprocket group 32G. , 6th and 7th stage).

  The displacement positions of the first, second and third stages of the front output cable 36 correspond to the drive sprockets 31 having a smaller diameter in order from the larger diameter of the third stage drive sprocket group 31G. The displacement positions of the fourth, fifth, sixth and seventh stages correspond to the driven sprockets 32 having a smaller diameter in order from the larger diameter of the seventh stage driven sprocket group 32G.

FIG. 5, which is developed by cutting the peripheral surface of the shift drum 61 in the axial direction, shows the circumferential position on the basis of the cutting position as a reference with the reference position being 0 ° for convenience.
The cable end 36b of the front output cable 36 and the cable end 38b of the rear output inner cable 38, which are fitted in the cam grooves 62F and 62R, respectively, have an opening of 90 °, and the displacement position is determined every 0 ° to 30 °. It is configured as follows.

In FIG. 5, the numbers attached to the sides of the cam grooves 62F and 62R indicate the gear positions, and the gear positions from the first speed to the eleventh speed are configured.
For example, when the gear stage having the largest gear ratio is 1st gear, the cable end 36b of the front output cable 36 is in the first position at the circumferential position of 30 °, and at the same time the cable end of the rear output inner cable 38. 38b is at the displacement position of the seventh step at the circumferential position of 300 °.

  The fact that the front output cable 36 is in the first-stage displacement position indicates that the front derailleur 35 selects the drive sprocket 31 with the largest diameter from the group of three-stage drive sprockets 31G and winds the chain 33 around it. The cable 38 is in the seventh stage displacement position, and the rear derailleur 37 selects the smallest diameter driven sprocket 32 from the seven stage driven sprocket group 32G and winds the chain 33 to achieve the maximum gear ratio. .

  In the case of the 11th speed with the smallest speed ratio, the cable end 36b of the front output cable 36 is located at the third-stage displacement position at the circumferential position of 90 °, and the drive sprocket 31 with the smallest diameter is selected. Since the cable end 38b of the output inner cable 38 is at the first-stage displacement position at the circumferential position of 0 ° and the driven sprocket 32 having the maximum diameter is selected, the minimum speed ratio is obtained.

  The shift drum is configured so that a shift in which the gear ratio decreases stepwise from the first speed to the eleventh speed is realized by one-way rotation of the shift drum 61 (rotation by pulling the input cable 41). Cam grooves 62F and 62R are formed on the peripheral surface of 61.

In this shift drum 61, when increasing the gear position, from the first gear to the seventh gear, the front output cable 36 is fixed at the displacement position of the first gear and the rear output inner cable 38 is moved from the seventh gear to the first gear. The displacement position is gradually lowered. At 8th speed, the front output cable 36 is displaced to the 2nd stage, but the rear output inner cable 38 returns to the 2nd stage, and at 9th speed, only the rear output inner cable 38 is displaced to the 1st stage. At the 10th speed, the front output cable 36 is displaced to the third stage, but the rear output inner cable 38 returns to the second stage, and at the 11th speed, only the rear output inner cable 38 is displaced to the first stage.
When the gear position is lowered, the reverse process is followed.

  FIG. 6 is a graph showing the change of the gear ratio with respect to the gear position, the broken line shown by the solid line is due to the multi-stage transmission 30, and the broken line shown by the broken line is the three-stage drive sprocket group 31G and the seven-stage driven sprocket A change in the gear ratio when the drive sprocket 31 and the driven sprocket 32 around which the chain 33 is wound from the group 32G is selected by different operating means is shown.

  When the drive sprocket 31 and the driven sprocket 32 are selected by different operating means, there are 21 combinations of the drive sprocket 31 and the driven sprocket 32, and there are several combinations in which the gear ratio is substantially the same.

  It is not easy for the rider to operate each of the other operating means to shift the 21 combinations in the order of the gear ratio, and it is not easy, and the drive sprocket 31 obtains the desired gear ratio in the intermediate gear ratio. It is not easy to select the combination of the driven sprocket 32 and the driven sprocket 32.

  However, in the case of the multi-stage transmission 30 using the distributor 50, if one shift operation lever 40 is operated to swing in one direction, the input displacement of the input cable 41 due to the swing operation can be reduced. Simultaneously convert the output displacement of the front output cable 36 and the output displacement of the rear output cable 38, and select the appropriate combination of drive sprocket 31 and driven sprocket 32 to decrease or increase the gear ratio stepwise. Shifting operation is easy.

  Further, since the swing position of the speed change operation lever 40 corresponds to the speed change ratio, it is easy to select a combination of the drive sprocket 31 and the driven sprocket 32 to obtain a desired speed change ratio.

The mechanical distributor 50 using the shift drum 61 in the multi-stage transmission 30 can easily achieve a desired gear ratio by a simple shift drum cam mechanism, and has a simple mechanical configuration and low cost. Can be achieved.
When the mechanical transmission mechanism provided in the conventional bicycle is replaced with the multi-stage transmission 30, the transmission operator can be used as it is without replacement, and the replacement cost can be reduced.

  In this distributor 50, the cable end 36b of the front output cable 36 is slidably fitted over both the cam groove 62F of the shift drum 61 and the linear groove 56F of the shift case 51, and the rear output cable 38 Since the cable end 38b is slidably fitted over both the other cam groove 62R of the shift drum 61 and the straight groove 56R of the shift case 51, each cable end 36b of the front output cable 36 and the rear output cable 38 is fitted. , 38b can be moved reliably and smoothly, and the distributor 50 can be reduced in size.

  The shift drum 61 of the distributor 50 has a structure that rotates directly by pulling the input cable 41. However, a gear mechanism may be interposed between the input cable 41 and the shift drum 61, or a gear mechanism is interposed. By doing so, the swinging amount of the shift operation lever 40 and the turning amount of the shift drum 61 can be easily set to an appropriate correspondence.

Next, a bicycle multi-stage transmission according to another embodiment will be described with reference to FIGS.
In the multi-stage transmission according to the present embodiment, a distributor 80 obtained by partially modifying the distributor 50 is attached to the steering shaft 11 of the bicycle 1.

The distributor 80 uses the cam mechanism of the shift drum 61 of the distributor 50 almost as it is, and substantially the same members use the same reference numerals.
As shown in FIG. 8, cam grooves 62F and 62R formed on the surface of a shift drum 82 rotatably accommodated in the shift case 81, linear grooves 56F and 56R formed inside the shift case 81, a lid Front output cable 36 extending from outer cable 36a, 38a having one end fitted into member 54, rear output cable 38, front output cable 36 slidably fitted over both cam groove 62F and linear groove 56F The cable end 36b, the cable end 38b of the rear output cable 38 slidably fitted over both the cam groove 62R and the straight groove 56R, and the like are the same as those of the distributor 50.

The distributor 80 projects the shaft 83 of the shift drum 82 through the bottom wall of the shift case 81 and protrudes to the outside.
The base end of the speed change operation lever 85 is fitted to the protruding portion of the shaft portion 83.
Therefore, if the shift operation lever 85 is swung, the shift drum 82 is directly rotated.

  A distributor 80 with such a shift operation lever 85 is attached to the steering shaft 11 with the shift operation lever 85 side up, and the front output cable 36 and the rear output cable 38 extending from the lower part of the distributor 80 are These are connected to the front derailleur 35 and the rear derailleur 37, respectively.

  No input cable is required, the distributor 80 itself is simplified, the number of parts is small, and the cost can be reduced.

Next, a modification of the speed change operation means is shown in FIGS.
In the embodiment, as shown in FIG. 1, the speed change lever 40 is attached to the steering shaft 11, but in the example shown in FIG. 9, the speed change lever 90 is provided in the vicinity of the left grip 13 of the handle 12. It is a thing.

The shift drum 61 of the distributor 50 is rotated via the input cable by the swing operation of the shift operation lever 90 to perform a shift.
Since the shift operation lever 90 can be operated while holding the grip 13, the shift operation is easy.

Further, in the example shown in FIG. 10, the swinging speed change operation lever 90 shown in FIG. 9 is a turning speed change operation ring 100, and the speed change operation ring 100 can be turned freely at the base of the left grip 13. I have.
The shift drum 61 of the distributor 50 is rotated through the input cable by the swing operation of the speed change operation ring 100 to perform the speed change.

As the shift operation means, the grip itself may be a rotational shift operation means.
In addition, in the case of a rotational shift operation means, the input drum can be eliminated by directly rotating the shift drum of the distributor.

1 is an overall perspective view of a bicycle to which a multi-stage transmission according to an embodiment of the present invention is applied. It is sectional drawing which shows the structure of the divider | distributor of this multistage transmission. It is sectional drawing cut | disconnected by the III-III line of FIG. It is sectional drawing cut | disconnected by the IV-IV line | wire of FIG. It is an expanded view of the cam groove of the surrounding surface of a shift drum. It is the graph which showed the change of the gear ratio with respect to the gear stage. It is a fragmentary perspective view of the bicycle concerning another embodiment. It is sectional drawing which shows the structure of the divider | distributor used for the bicycle. It is a fragmentary perspective view of the bicycle of another modification. Moreover, it is a fragmentary perspective view of the bicycle of another modification.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Bicycle, 30 ... Multi-stage transmission, 31G ... Drive sprocket group, 31 ... Drive sprocket group, 32G ... Driven sprocket group, 32 ... Driven sprocket group, 33 ... Chain, 35 ... Front derailleur, 36 ... Front output cable, 37 ... Rear Derailleur, 38 ... Rear output cable, 40 ... Shifting lever, 41 ... Input cable,
50 ... Distributor, 51 ... Shift case, 52 ... Cylindrical part, 53 ... Bottom wall, 54 ... Lid member, 61 ... Shift drum, 62 ... Drum body part, 62F ... Cam groove, 62R ... Cam groove, 63 ... Shaft 65, cable entrainment groove, 66 ... coil spring,
80 ... Distributor, 81 ... Shift case, 82 ... Shift drum, 83 ... Shaft, 85 ... Shifting operation lever, 90 ... Shifting operation lever, 100 ... Shifting operation ring.

Claims (2)

The front derailleur and the rear derailleur are driven by the operation of the speed changer supported by the body frame,
A bicycle drive sprocket is selected in which a chain is transferred from a multistage drive sprocket by driving the front derailleur, and a driven sprocket in which a chain is extended from a multistage driven sprocket is selected by driving the rear derailleur. In a multi-stage transmission,
A mechanical type in which one input of the speed changer is divided into two outputs, one output drives the front derailleur via a front output cable, and the other output drives the rear derailleur via a rear output cable. A distributor is provided,
The distributor is
A shift drum having two cam grooves each having a predetermined shape based on a predetermined input / output relationship on an outer peripheral surface of the rotating drum ;
The shift drum rotates to a rotation angle position corresponding to the input displacement of the shift operation element,
The cable end of the front output cable and the cable end of the rear output cable are slidably fitted into the cam grooves of the shift drum,
The input displacement of the shift operation element is converted into the output displacement of the front output cable in the drum rotation center axis direction by the rotation of the shift drum, and the output of the rear output cable in the drum rotation center axis direction is converted. A multi-stage transmission for a bicycle characterized by being converted into displacement . The shift drum of the distributor is covered with a shift case fixed to the vehicle body frame,
On the inner peripheral surface of the shift case facing the outer peripheral surface of the shift drum, a linear groove oriented in the drum rotation central axis direction is formed,
The cable end of the front output cable is slidably fitted across both the cam groove of the shift drum and the linear groove of the shift case,
2. The multi-speed shift of a bicycle according to claim 1, wherein a cable end of the rear output cable is slidably fitted over both the other cam groove of the shift drum and the linear groove of the shift case. Machine.

Images