TWI725292B - Bicycle sprocket assembly and bicycle drive train - Google Patents

Abstract

A bicycle sprocket assembly comprises a plurality of sprockets comprising at least twelve sprockets having different numbers of teeth. The at least twelve sprockets are coaxially arranged along a rotational center axis of the bicycle sprocket assembly. An entire gear range of the plurality of sprockets is equal to or larger than 360 %. An average percentage gear stage step of the plurality of sprockets being equal to or larger than 10 %. The average percentage gear stage step of the plurality of sprockets is smaller than 15 %.

Description

Bicycle sprocket assembly and bicycle transmission system

The invention relates to a bicycle sprocket assembly and a bicycle transmission system.

Cycling is becoming an increasingly popular form of leisure and a means of transportation. Furthermore, cycling has become a very popular competitive sport for amateurs and professional players. Regardless of whether the bicycle is used for leisure, transportation or competition, the bicycle industry is constantly improving the various components of the bicycle. A bicycle component sprocket assembly that has been extensively redesigned.

According to a first aspect of the present invention, a bicycle sprocket assembly includes a plurality of sprockets, which include at least twelve sprockets with different numbers of teeth. The at least twelve sprockets are coaxially arranged along a rotation center axis of the bicycle sprocket assembly. The entire gear range of one of the plurality of sprockets is equal to or greater than 360%. The average percentage gear level of one of the plurality of sprockets is equal to or greater than 10%. The average percentage gear level of the plurality of sprockets is less than 15%. With the bicycle sprocket assembly according to the first aspect, the bicycle sprocket assembly having a wide gear range and a well-balanced combination of one of the plurality of sprockets can be provided. According to a second aspect of the present invention, the bicycle sprocket assembly according to the first aspect is configured such that the average percentage gear level of the plurality of sprockets is in the range from 12% to 14%. With the bicycle sprocket assembly according to the second aspect, it is possible to provide the bicycle sprocket assembly having a more well-balanced combination of one of the plurality of sprockets. According to a third aspect of the present invention, the bicycle sprocket assembly according to the first aspect or the second aspect is configured such that the plurality of sprockets includes a first sprocket. The first sprocket includes a first sprocket body and a plurality of first sprocket teeth extending radially outward from the first sprocket body. The plurality of first sprocket teeth include at least one first tooth and at least one second tooth. The at least one first tooth has a first maximum axial width. The at least one second tooth has a second maximum axial width. The first maximum axial width is greater than the second maximum axial width. With the bicycle sprocket assembly according to the third aspect, the chain retention efficiency of the first sprocket can be improved. According to a fourth aspect of the present invention, the bicycle sprocket assembly according to the first aspect is configured such that the first sprocket has a first pitch circle diameter that is the largest among the plurality of sprockets. With the bicycle sprocket assembly according to the fourth aspect, the chain retention efficiency of the first sprocket with the largest pitch circle diameter can be improved. According to a fifth aspect of the present invention, the bicycle sprocket assembly according to any one of the first aspect to the fourth aspect is configured such that the plurality of sprockets includes an inner space. The internal space includes a first end opening and a second end opening. The internal space extends between the first end opening and the second end opening along the rotation center axis. With the bicycle sprocket assembly according to the fifth aspect, the weight of the bicycle sprocket assembly can be saved. According to a sixth aspect of the present invention, the bicycle sprocket assembly according to the fifth aspect is configured such that the first end opening has a first inner diameter. The second end opening has a second inner diameter. The first inner diameter is larger than the second inner diameter. With the bicycle sprocket assembly according to the sixth aspect, the weight of the bicycle sprocket assembly can be effectively saved. According to a seventh aspect of the present invention, the bicycle sprocket assembly according to any one of the first aspect to the sixth aspect further includes a hub engaging member attached to the plurality of sprockets To engage with a bicycle hub assembly. The hub engaging component includes an internal thread that is configured to engage with an external thread of the bicycle hub assembly. With the bicycle sprocket assembly according to the seventh aspect, the bicycle sprocket assembly can be easily installed to the bicycle hub assembly. According to an eighth aspect of the present invention, the bicycle sprocket assembly according to any one of the first aspect to the seventh aspect is configured such that the plurality of sprockets includes a smallest sprocket. The smallest sprocket has the smallest pitch circle diameter among the plurality of sprocket wheels and a total number of teeth equal to or less than ten. With the bicycle sprocket assembly according to the eighth aspect, the bicycle sprocket assembly with a wider gear range can be provided. According to a ninth aspect of the present invention, the bicycle sprocket assembly according to any one of the first aspect to the eighth aspect is configured such that the plurality of sprockets includes a largest sprocket. The largest sprocket has the largest pitch circle diameter among the plurality of sprockets and a total number of teeth equal to or greater than 36. With the bicycle sprocket assembly according to the ninth aspect, the bicycle sprocket assembly with a wider gear range can be provided. According to a tenth aspect of the present invention, a bicycle transmission system includes a bicycle sprocket assembly and a bicycle rear derailleur. The bicycle sprocket assembly includes a plurality of sprockets, which include at least twelve sprockets with different numbers of teeth. The at least twelve sprockets are coaxially arranged along a rotation center axis of the bicycle sprocket assembly. The entire gear range of one of the plurality of sprockets is equal to or greater than 360%. The average percentage gear level of one of the plurality of sprockets is equal to or greater than 10%. The average percentage gear level of the plurality of sprockets is less than 15%. The bicycle rear derailleur includes a base part, a movable part, a chain guide and a resistance applying element. The base member is configured to be mounted to a bicycle frame. The movable part is movably coupled to the base part. The chain guide is coupled to the movable part for rotating around a rotation axis of a pivot shaft. The resistance applying element will apply resistance to the rotational movement of one of the chain guides. By virtue of the bicycle transmission system according to the tenth aspect, the bicycle transmission system including the bicycle sprocket assembly having a wide gear range and a well-balanced combination of the plurality of sprockets can be provided. According to an eleventh aspect of the present invention, the bicycle transmission system according to the tenth aspect is configured such that the bicycle rear derailleur further includes a linkage group that interconnects the base member and the movable Part to allow the movable part to move relative to one of the base parts. The connecting rod group includes a connecting rod group axis, and the connecting rod group axis is oriented orthogonally to a direction parallel to the rotation center axis of the bicycle sprocket assembly. With the bicycle sprocket assembly according to the eleventh aspect, the bicycle transmission system including the bicycle sprocket assembly having a wide gear range and a well-balanced combination of the plurality of sprockets can be provided. According to a twelfth aspect of the present invention, a bicycle transmission system includes a bicycle rear sprocket assembly and a bicycle crank assembly. The bicycle rear sprocket assembly includes a plurality of sprockets, which include at least twelve sprockets with different numbers of teeth. The at least twelve sprockets are coaxially arranged along a rotation center axis of the bicycle sprocket assembly. The entire gear range of one of the plurality of sprockets is equal to or greater than 360%. The average percentage gear level of one of the plurality of sprockets is equal to or greater than 10%. The average percentage gear level of the plurality of sprockets is less than 15%. The bicycle crank assembly includes a single front sprocket. By virtue of the bicycle sprocket assembly according to the twelfth aspect, the bicycle transmission system including the bicycle sprocket assembly having a wide gear range and a well-balanced combination of the plurality of sprockets can be provided.

The embodiment(s) will now be described with reference to the accompanying drawings, in which throughout the various drawings, the same element symbols indicate corresponding or identical elements. First Embodiment Referring first to FIG. 1, a bicycle 10 includes a bicycle transmission system 12 according to a first embodiment. The bicycle 10 further includes a bicycle frame B1, a handle B2, a seat B3, a front wheel B4, and a rear wheel B5. The handle B2 is pivotally coupled to the bicycle frame B1. The seat B3 is attached to a seat tube B6 that is mounted to the bicycle frame B1. In this application, the following directional terms "front", "back", "forward", "backward", "left", "right", "horizontal", "up" and "down" and any other similar The direction term refers to the directions determined based on a user (for example, a rider) sitting on a seat B3 of the bicycle 10 and facing the handle B2. Therefore, the terms used to describe the bicycle transmission system 12 should be interpreted relative to a bicycle equipped with the bicycle transmission system 12 as used in an upright riding position on a horizontal surface. As seen in FIG. 1, the bicycle transmission system 12 includes a bicycle sprocket assembly RS and a bicycle rear derailleur RD. In this embodiment, the bicycle sprocket assembly RS is a bicycle rear sprocket assembly. The bicycle sprocket assembly RS can also be referred to as a bicycle rear sprocket assembly RS. However, the structure of the bicycle sprocket assembly RS can be applied to a front sprocket FS. The bicycle transmission system 12 includes a bicycle rear sprocket assembly RS and a bicycle crank assembly CA. The bicycle crank assembly CA includes a single front sprocket FS. However, the total number of one of the front sprockets is not limited to this embodiment. In one of the cases where the bicycle crank assembly CA includes a plurality of front sprockets, the bicycle transmission system 12 includes a front derailleur. The bicycle crank assembly CA includes a crank shaft and a crank arm. The crank arm is fastened to the crank shaft. The front sprocket FS is fastened to at least one of the crank arm and the crank shaft to rotate together. The bicycle transmission system 12 includes a bicycle chain C that is engaged with the front sprocket FS and the bicycle sprocket assembly RS to transmit a rotational force F1 (FIG. 2) from the front sprocket FS to the bicycle sprocket assembly RS. As seen in FIG. 2, the bicycle sprocket assembly RS has a rotation center axis A1 and is rotatably supported by the bicycle hub assembly 14 relative to the bicycle frame B1 about the rotation center axis A1. The bicycle sprocket assembly RS can rotate around the rotation center axis A1 in a driving rotation direction D11 during pedaling. A reverse rotation direction D12 is opposite to the drive rotation direction D11. The driving rotation direction D11 and the reverse rotation direction D12 are defined along a circumferential direction D1 of the bicycle sprocket assembly RS. The circumferential direction D1 is defined around the rotation center axis A1 of the bicycle sprocket assembly RS. Bicycle sprocket assembly RS (Bicycle rear sprocket assembly RS) includes a plurality of sprockets. The plurality of sprockets includes at least twelve sprockets with different numbers of teeth. In this embodiment, the plurality of sprockets includes a largest sprocket RS1. The plurality of sprockets includes a smallest sprocket RS12. Specifically, the plurality of sprockets includes a first sprocket RS1. The plurality of sprockets includes second sprockets RS2 to twelfth sprockets RS12. The first sprocket RS1 corresponds to the largest sprocket in the bicycle sprocket assembly RS. The twelfth sprocket RS12 corresponds to the smallest sprocket RS12 in the bicycle sprocket assembly RS. Therefore, the first sprocket RS1 can also be referred to as the largest sprocket RS1, and the twelfth sprocket RS12 can also be referred to as the smallest sprocket RS12. The first sprockets RS1 to the twelfth sprockets RS12 may also be referred to as sprockets RS1 to RS12, respectively. The total number of one of the sprockets is not limited to this embodiment. The first sprocket (largest sprocket) RS1 includes a first sprocket body RS1A and a plurality of first sprocket teeth RS1B extending radially outward from the first sprocket body RS1A. The second sprocket RS2 includes a second sprocket body RS2A and a plurality of second sprocket teeth RS2B extending radially outward from the second sprocket body RS2A. The third sprocket RS3 includes a third sprocket body RS3A and a plurality of third sprocket teeth RS3B extending radially outward from the third sprocket body RS3A. The fourth sprocket RS4 includes a fourth sprocket body RS4A and a plurality of fourth sprocket teeth RS4B extending radially outward from the fourth sprocket body RS4A. The fifth sprocket RS5 includes a fifth sprocket body RS5A and a plurality of fifth sprocket teeth RS5B extending radially outward from the fifth sprocket body RS5A. The sixth sprocket RS6 includes a sixth sprocket body RS6A and a plurality of sixth sprocket teeth RS6B extending radially outward from the sixth sprocket body RS6A. The seventh sprocket RS7 includes a seventh sprocket body RS7A and a plurality of seventh sprocket teeth RS7B extending radially outward from the seventh sprocket body RS7A. The eighth sprocket RS8 includes an eighth sprocket body RS8A and a plurality of eighth sprocket teeth RS8B extending radially outward from the eighth sprocket body RS8A. The ninth sprocket RS9 includes a ninth sprocket body RS9A and a plurality of ninth sprocket teeth RS9B extending radially outward from the ninth sprocket body RS9A. The tenth sprocket RS10 includes a tenth sprocket body RS10A and a plurality of tenth sprocket teeth RS10B extending radially outward from the tenth sprocket body RS10A. The eleventh sprocket RS11 includes an eleventh sprocket body RS11A and a plurality of eleventh sprocket teeth RS11B extending radially outward from the eleventh sprocket body RS11A. The twelfth sprocket (the smallest sprocket) RS12 includes a twelfth sprocket body RS12A and a plurality of twelfth sprocket teeth RS12B extending radially outward from the twelfth sprocket body RS12A. In this embodiment, the largest sprocket RS1 has a total number of teeth equal to or greater than 36. The smallest sprocket RS12 has a total number of teeth equal to or less than ten. Specifically, the total number of one of the first sprocket teeth RS1B is 36. The total number of one of the second sprocket teeth RS2B is 33. The total number of one of the third sprocket RS3B is 30. The total number of one of the fourth sprocket RS4B is 27. The total number of one of the fifth sprocket RS5B is 24. The total number of one of the sixth sprocket RS6B is 22. The total number of one of the seventh sprocket RS7B is 20. The total number of one of the eighth sprocket RS8B is 18. The total number of one of the ninth sprocket RS9B is 16. The total number of one of the tenth sprocket RS10B is 14. The total number of one of the eleventh sprocket RS11B is 12. The total number of one of the twelfth sprocket RS12B is 10. The largest sprocket (first sprocket) RS1 has the largest pitch circle diameter (first pitch circle diameter) PCD1 among the plurality of sprockets RS1 to RS12. The smallest sprocket RS12 has a pitch circle diameter PCD12 that is the smallest among the plurality of sprockets RS1 to RS12. The largest sprocket (first sprocket) RS1 corresponds to the low gear in the bicycle sprocket assembly RS. The smallest sprocket (twelfth sprocket) RS12 corresponds to the high gear in the bicycle sprocket assembly RS.

As seen in FIG. 3, the entire gear range (EGR) of one of the plurality of sprockets RS1 to RS12 is equal to or greater than 360%. The entire gear range of multiple sprockets RS1 to RS12 is equal to or less than 400%. In this embodiment, the entire gear range of the plurality of sprockets RS1 to RS12 is 360%. However, the entire gear range of the plurality of sprockets RS1 to RS12 is not limited to this embodiment and the above range.

The entire gear range of the plurality of sprockets RS1 to RS12 is defined as the ratio of the total number of the first sprocket RS1B of the largest gear RS1 to the total number of the twelfth sprocket RS12B of the smallest sprocket RS12.

The average percentage gear step (APGS) of one of the plurality of sprockets RS1 to RS12 is equal to or greater than 10%. The average percentage gear level of multiple sprockets RS1 to RS12 is less than 15%. The average percentage gear level of the plurality of sprockets RS1 to RS12 is preferably in the range of 12% to 14%. The average percentage gear level of multiple sprockets RS1 to RS12 is 12.4%. However, the average percentage gear level of the plurality of sprockets RS1 to RS12 is not limited to this embodiment and the above range.

The average percentage gear level of the plurality of sprockets RS1 to RS12 is defined as an average of the individual percentage gear levels of the sprockets RS1 to RS12. The individual percentage gear level is defined as the difference between the total number of teeth of a larger sprocket and the total number of teeth of a smaller sprocket directly axially adjacent to the larger sprocket and the total of the smaller sprocket A ratio of the number of teeth. For example, the individual percentage gear level (9.1%) between sprocket RS1 and RS2 is defined as the difference (3) between the total number of teeth of sprocket RS1 (36) and the total number of teeth of sprocket RS2 (33) and the chain A ratio of the total number of teeth (33) of the wheel RS2. However, the average percentage gear level is not limited to this embodiment and above. In the embodiment of FIG. 3, the difference between a maximum value of a specific percentage gear level and a minimum value of the specific percentage gear level The value is greater than half of the average percentage gear level.

As seen in Figure 3, the modifications M1 to M6 can be applied to the bicycle sprocket assembly RS.

In the modification M1, the total number of teeth of the first sprocket RS1 to the twelfth sprocket RS12 is 10, 11, 12, 13, 14, 16, 18, 21, 24, 28, 32, and 36. The entire gear range of the plurality of sprockets RS1 to RS12 is 360%, and the average percentage gear level of the plurality of sprockets RS1 to RS12 is 12.4%.

In the modification M2, the total number of teeth of the first sprocket RS1 to the twelfth sprocket RS12 is 10, 11, 12, 14, 16, 18, 21, 24, 28, 32, 36, and 40. The entire gear range of the plurality of sprockets RS1 to RS12 is 400%, and the average percentage gear level of the plurality of sprockets RS1 to RS12 is 13.5%.

In the modification M3, the total number of teeth of the first sprocket RS1 to the twelfth sprocket RS12 is 10, 12, 14, 16, 18, 21, 24, 27, 30, 33, 36, and 40. The entire gear range of the plurality of sprockets RS1 to RS12 is 400%, and the average percentage gear level of the plurality of sprockets RS1 to RS12 is 13.5%.

In the modification M4, the total number of teeth of the first sprocket RS1 to the twelfth sprocket RS12 is 10, 12, 14, 16, 18, 20, 22, 24, 28, 32, 36, and 40. The entire gear range of the plurality of sprockets RS1 to RS12 is 400%, and the average percentage gear level of the plurality of sprockets RS1 to RS12 is 13.5%.

In the modification M5, the total number of teeth of the first sprocket RS1 to the twelfth sprocket RS12 is 10, 12, 14, 16, 18, 20, 22, 24, 28, 32, 36, and 42. The entire gear range of the plurality of sprockets RS1 to RS12 is 420%, and the average percentage gear level of the plurality of sprockets RS1 to RS12 is 14.0%.

In the modification M6, the total number of teeth of the first sprocket RS1 to the twelfth sprocket RS12 is 11, 13, 15, 17, 19, 21, 24, 27, 30, 33, 36, and 40. The entire gear range of the plurality of sprockets RS1 to RS12 is 364%, and the average percentage gear level of the plurality of sprockets RS1 to RS12 is 12.5%. In a reference example RE, the total number of teeth of the first sprocket RS1 to the twelfth sprocket RS12 is 11, 13, 15, 17, 19, 21, 23, 25, 27, 30, 33, and 36. The entire gear range of the plurality of sprockets RS1 to RS12 is 327%, and the average percentage gear level of the plurality of sprockets RS1 to RS12 is 11.4%. As seen in FIG. 4, at least twelve sprockets RS1 to RS12 are coaxially arranged along the rotation center axis A1 of the bicycle sprocket assembly RS. The bicycle sprocket assembly RS is installed to a bicycle hub assembly 14. A rotor locking member 18 is used to fasten a brake rotor 16 to the bicycle hub assembly 14. As seen in FIG. 5, the plurality of sprockets RS1 to RS12 includes an inner space 20. The internal space 20 includes a first end opening 22 and a second end opening 24. The internal space 20 extends between the first end opening 22 and the second end opening 24 along the rotation center axis A1. The first end opening 22 has a first inner diameter DM1. The second end opening 24 has a second inner diameter DM2. The first inner diameter DM1 is greater than the second inner diameter DM2. However, the first inner diameter DM1 may be equal to or smaller than the second inner diameter DM2. In this embodiment, the second sprocket RS2 to the twelfth sprocket RS12 are provided integrally with each other as a single-piece unitary component. The first sprocket RS1 is a part separated from the second sprocket RS2 to the twelfth sprocket RS12 and is fastened to the second sprocket RS2 using a plurality of pins (not shown). However, the first sprocket RS1 may be provided integrally with the second sprocket RS2. In this embodiment, the first sprocket RS1 is made of a metal material (such as iron, aluminum, titanium, and stainless steel). The second sprocket RS2 to the twelfth sprocket RS12 are made of a metal material such as iron, aluminum, titanium, and stainless steel. However, the materials of the first sprocket RS1 to the twelfth sprocket RS12 are not limited to this embodiment. The bicycle sprocket assembly RS further includes a hub engaging part 26 that is attached to the plurality of sprockets RS1 to RS12 to be engaged with the bicycle hub assembly 14. The hub engaging member 26 is rotatably provided between the first sprocket RS1 and the tenth sprocket RS10. The hub engaging member 26 includes an internal thread 26A. The internal thread 26A is configured to engage with one of the external threads 28 of the bicycle hub assembly 14. As seen in FIG. 4, the bicycle hub assembly 14 includes a hub axle 30, a hub body 32, a sprocket support structure 34 and a brake rotor support structure 36. The hub body 32 is rotatably supported on the hub axle 30 around a rotation center axis A1 of the bicycle hub assembly 14. The hub body 32 has a first body end 32A and a second body end 32B. The second body end 32B is opposite to the first body end 32A with respect to the rotation center axis A1 in an axial direction D2. In this embodiment, the first body end 32A is a right end of the hub body 32, and the second body end 32B is a left end of the hub body 32. However, the first body end 32A may be a left end, and the second body end 32B may be a right end. The sprocket support structure 34 is configured to support the bicycle sprocket assembly RS. The sprocket support structure 34 is closer to the first body end 32A than the brake rotor support structure 36 in the axial direction D2. The sprocket support structure 34 is rotatably mounted on the hub axle 30 around the rotation center axis A1. In this embodiment, as seen in FIG. 5, the bicycle hub assembly 14 includes a first bearing 37A and a second bearing 37B. The first bearing 37A and the second bearing 37B are disposed between the sprocket support structure 34 and the hub axle 30 to rotatably support the sprocket support structure 34 relative to the hub axle 30. As seen in FIG. 4, the brake rotor support structure 36 is configured to support the brake rotor 16. The brake rotor support structure 36 is disposed at the end 32B of the second body. The brake rotor support structure 36 is rotatably mounted on the hub axle 30 around the rotation center axis A1. The brake rotor support structure 36 is coupled to the hub body 32 to rotate integrally with the hub body 32 relative to the hub axle 30 about the rotation center axis A1. In this embodiment, the brake rotor support structure 36 and the hub body 32 are integrally provided as a single one-piece component. However, the brake rotor support structure 36 may be a separate component from the hub body 32. As seen in FIG. 5, the sprocket support structure 34 is a separate component from the hub body 32. The bicycle hub assembly 14 includes a ratchet structure 38. The sprocket support structure 34 is operatively coupled to the hub body 32 using a ratchet structure 38. The ratchet structure 38 is configured to couple the sprocket support structure 34 to the hub body 32 to rotate the sprocket support structure 34 together with the hub body 32 in one rotation direction during pedaling. The ratchet structure 38 is configured to allow the sprocket support structure 34 to rotate relative to the hub body 32 in another rotational direction during sliding. The ratchet structure 38 includes a structure known in the bicycle field. Therefore, they will not be described in detail in this article for the sake of brevity. As seen in FIG. 6, the sprocket support structure 34 includes a first torque transmission profile 40 and external threads 28. The first torque transmission profile 40 is configured to transmit the rotational force F1 between the sprocket support structure 34 and the bicycle sprocket assembly RS. The first torque transmission profile 40 includes a first spline portion 44. In this embodiment, the sprocket support structure 34 includes a base portion 46 having a tubular shape. The first torque transmission profile 40 and the external thread 28 are provided on an outer peripheral surface 46A of the base portion 46. The sprocket supporting structure 34 includes a sprocket stopper 47. The first torque transmission profile 40 is arranged between the external thread 28 and the sprocket stop 47 in the axial direction D2. As seen in FIG. 5, the first spline portion 44 is configured to engage with a sprocket spline portion 48 of the bicycle sprocket assembly RS. In this embodiment, the largest sprocket RS1 includes a sprocket spline portion 48. The sprocket support structure 34 is a separate component from the hub engaging component 26. The external thread 28 is configured to threadedly engage with the internal thread 26A of the hub engaging part 26. The hub engagement member 26 is configured to prevent the bicycle sprocket assembly RS from axially moving relative to one of the sprocket support structures 34 in a state in which the hub engagement member 26 is attached to the sprocket support structure 34. In a state in which the hub engagement member 26 is attached to the sprocket support structure 34, the largest sprocket RS1 is disposed between the hub engagement member 26 and the sprocket stopper 47 in the axial direction D2. The hub engaging member 26 is rotatably coupled to a plurality of sprockets RS1 to RS12. The hub engaging member 26 is coupled to the plurality of sprockets RS1 to RS12 to move integrally with the plurality of sprockets RS1 to RS12 in the axial direction D2. In this embodiment, the bicycle hub assembly 14 includes a hub engaging member 26. However, the bicycle sprocket assembly RS may include a hub engaging part 26. As seen in FIG. 2, the plurality of first sprocket teeth RS1B includes at least one first tooth 52 and at least one second tooth 54. In this embodiment, the plurality of first sprocket teeth RS1B includes a plurality of first teeth 52 and a plurality of second teeth 54. The first teeth 52 and the second teeth 54 are alternately arranged in the circumferential direction D1. As seen in FIG. 7, the first teeth 52 extend radially outward from the first sprocket body RS1A to engage with an outer chain space C11 defined between a pair of opposite outer chain plates C1 of the bicycle chain C. At least one first tooth 52 has a first maximum axial width W1. The first maximum axial width W1 is smaller than one of the axial lengths of the outer chain space C11. The first tooth 52 includes a first axial surface 52A and a first additional axial surface 52B. The first additional axial surface 52B is provided on one of the opposite sides of the first axial surface 52A in the axial direction D2. The first maximum axial width W1 extends in the axial direction D2 from the first axial surface 52A to the first additional axial surface 52B. As seen in FIG. 8, the second teeth 54 extend radially outward from the first sprocket body RS1A to engage with an inner chain space C21 defined between a pair of opposed inner chain plates C2 of the bicycle chain C. At least one second tooth 54 has a second maximum axial width W2. The first maximum axial width W1 is greater than the second maximum axial width W2. The first maximum axial width W1 is greater than one of the axial lengths of the inner chain space C21. The second maximum axial width W2 is smaller than the axial length of the inner chain space C21. The second tooth 54 includes a second axial surface 54A and a second additional axial surface 54B. The second additional axial surface 54B is provided on one of the opposite sides of the second axial surface 54A in the axial direction D2. The second maximum axial width W2 extends in the axial direction D2 from the second axial surface 54A to the second additional axial surface 54B. The first maximum axial width W1 may be equal to or smaller than the second maximum axial width W2. As seen in FIG. 9, the bicycle rear derailleur RD includes a base part RD1, a movable part RD2, and a chain guide RD3. The base part RD1 is configured to be mounted to the bicycle frame B1. The movable part RD2 is movably coupled to the base part RD1. The chain guide RD3 is coupled to the movable part RD2 for rotating around a rotation axis A3 of a pivot shaft RD4. The bicycle rear derailleur RD further includes a link group RD5 that interconnects the base part RD1 and the movable part RD2 to allow the movable part RD2 to move relative to one of the base parts RD1. The link set RD5 includes a link set axis A5, which is oriented orthogonally to the direction (axial direction) D2 parallel to the rotation center axis A1 of the bicycle sprocket assembly RS. The bicycle rear derailleur RD includes a resistance applying element RD6 to apply resistance to the rotational movement of one of the chain guides RD3. The resistance applying element RD6 is provided in the movable member RD2. For example, the resistance applying element RD6 includes a one-way clutch and a friction applying member. The one-way clutch applies resistance to the rotational movement of the chain guide RD3 in a predetermined direction. The friction applying member applies frictional resistance to the rotation of the chain guide RD3 by applying frictional resistance to the rotation of the one-way clutch. The bicycle rear derailleur RD includes a structure known in the bicycle field. Therefore, they will not be described in detail in this article for the sake of brevity. The term "comprise" and its derivatives used in this article are intended to be open terms, which designate the existence of stated features, elements, components, groups, integers and/or steps, but do not exclude other unstated features, The existence of elements, components, groups, integers, and/or steps. This concept also applies to words with similar meanings, for example, the terms "have", "include" and their derivatives. The terms "part", "section", "part", "part", "component", "body" and "structure" when used in the singular can have the dual meaning of a single part or plural parts. The ordinal numbers such as "first" and "second" stated in this application are only identifiers and do not have any other meanings (for example, a specific order and the like). Furthermore, for example, the term “first element” itself does not imply the existence of “second element”, and the term “second element” itself does not imply the existence of “first element”. In addition to configurations in which a pair of elements have the same shape or structure as each other, the term "pair" as used herein can also cover a configuration in which the pair of elements have different shapes or structures from each other. The terms "a" (or "one"), "one or more" and "at least one" can be used interchangeably herein. Finally, degree terms (such as "substantially", "approximately" and "approximately" as used herein) mean a reasonable amount of deviation from one of the modified terms so that the final result does not change significantly. All numerical values described in this application can be interpreted as including terms such as "substantially", "approximately" and "approximately". Obviously, in view of the above teachings, many modifications and variations of the present invention are possible. Therefore, it should be understood that, within the scope of the appended invention application, the present invention can be practiced in other ways than specifically described herein.

10‧‧‧Bicycle 12‧‧‧Bicycle transmission system14‧‧‧Bicycle hub assembly16‧‧‧Brake rotor 18‧‧‧Rotor locking part 20‧‧‧Internal space 22‧‧‧First end opening 24‧‧ ‧Second end opening 26‧‧‧Hub joint part 26A‧‧‧Internal thread 28‧‧‧External thread 30‧‧‧Hub shaft 32‧‧‧Hub body 32A‧‧‧First body end 32B‧‧‧Second Body end 34‧‧‧Sprocket support structure 36‧‧‧Brake rotor support structure 37A‧‧‧First bearing 37B‧‧‧Second bearing 38‧‧‧Ratchet structure 40‧‧‧First torque transmission profile 44‧ ‧‧First spline part 46‧‧‧Base part 46A‧‧‧Outer peripheral surface 47‧‧‧Sprocket stopper 48‧‧‧Sprocket spline part 52‧‧‧First tooth 52A‧‧‧ First axial surface 52B‧‧‧First additional axial surface 54‧‧‧Second tooth 54A‧‧‧Second axial surface 54B‧‧‧Second additional axial surface A1‧‧‧Central axis of rotation A3‧ ‧‧Rotation axis A5‧‧‧Link group axis B1‧‧‧Bicycle frame B2‧‧‧Handlebar B3‧‧‧Seat B4‧‧‧Front wheel B5‧‧‧Rear wheel B6‧‧‧Seat tube C‧‧‧ Bicycle chain C1‧‧‧Outer chain plate C2‧‧‧Inner chain plate C11‧‧‧Outer chain space C21‧‧‧Inner chain space CA‧‧‧Bicycle crank assembly D1‧‧‧Circumferential direction D2‧‧‧Axial Direction D11‧‧‧Drive rotation direction D12‧‧‧Reverse rotation direction DM1‧‧‧First inner diameter DM2‧‧‧Second inner diameter F1‧‧‧Rotational force FS‧‧‧Front sprocket M1-M6‧‧ ‧Modified PCD1‧‧‧Pitch circle diameter PCD12‧‧‧Pitch circle diameter RD‧‧‧Bicycle rear derailleur RD1‧‧‧Base part RD2‧‧‧Movable part RD3‧‧‧Chain guide RD4‧‧‧Pivot shaft RD5‧‧‧Connecting rod group RD6‧‧‧Resistance applying element RS‧‧‧Bicycle sprocket assembly RS1‧‧‧First sprocket RS1A‧‧‧First sprocket body RS1B‧‧‧First sprocket tooth RS2‧‧‧Second Sprocket RS2A‧‧‧Second Sprocket RS2B‧‧‧Second Sprocket RS3‧‧‧Third Sprocket RS3A‧‧‧Third Sprocket RS3B‧‧‧Third Chain Gear RS4‧‧‧Fourth sprocket RS4A‧‧‧Fourth sprocket RS4B‧‧‧Fourth sprocket RS5‧‧‧Fifth sprocket RS5A‧‧‧Fifth sprocket RS5B‧‧‧Second Five sprocket RS6‧‧‧Sixth sprocket RS6A‧‧‧Sixth sprocket RS6B‧‧‧Sixth sprocket RS7‧‧‧Seventh sprocket RS7A‧‧‧Seventh sprocket RS7B‧‧ ‧Seventh sprocket RS8‧‧‧Eighth sprocket RS8A‧‧‧Eighth sprocket RS8B‧‧‧Eighth sprocket RS9‧‧‧Ninth sprocket RS9A‧‧‧Ninth sprocket RS9B ‧‧‧Ninth sprocket RS10‧‧‧Tenth sprocket RS10A‧‧ ‧The tenth sprocket RS10B‧‧‧the tenth sprocket RS11‧‧‧the eleventh sprocket RS11A‧‧‧the eleventh sprocket RS11B‧‧‧the eleventh sprocket RS12‧‧‧the tenth Two sprocket W1‧‧‧The first maximum axial width W2‧‧‧The second maximum axial width

Since the present invention and its many accompanying advantages become understood by referring to the following embodiments when considered in conjunction with the accompanying drawings, it will be easy to obtain a more complete understanding of the present invention and one of its many accompanying advantages. Fig. 1 is a side view of a bicycle including a bicycle transmission system according to an embodiment. Fig. 2 is a side view of a bicycle sprocket assembly of the bicycle transmission system shown in Fig. 1. Figure 3 is a table showing various combinations of the sprocket of the bicycle sprocket assembly shown in Figure 2. Fig. 4 is a rear view of the bicycle sprocket assembly, a bicycle hub assembly and a brake rotor of the bicycle transmission system shown in Fig. 1. Fig. 5 is a cross-sectional view of the bicycle sprocket assembly and bicycle hub assembly of the bicycle transmission system shown in Fig. 1. Fig. 6 is a perspective view of a sprocket supporting structure of the bicycle hub assembly shown in Fig. 4. Fig. 7 is a cross-sectional view of a sprocket of the bicycle sprocket assembly shown in Fig. 2. Fig. 8 is another cross-sectional view of the sprocket of the bicycle sprocket assembly shown in Fig. 2. Fig. 9 is a side view of a bicycle rear derailleur of the bicycle transmission system shown in Fig. 1.

RS1‧‧‧First sprocket

RS2‧‧‧Second Sprocket

RS3‧‧‧The third sprocket

RS4‧‧‧Fourth sprocket

RS5‧‧‧Fifth sprocket

RS6‧‧‧Sixth sprocket

RS7‧‧‧Seventh sprocket

RS8‧‧‧Eighth Sprocket

RS9‧‧‧Ninth sprocket

RS10‧‧‧Tenth sprocket

RS11‧‧‧Eleventh sprocket

RS12‧‧‧Twelfth Sprocket

M1-M6‧‧‧Modify

Claims (12)

A bicycle sprocket assembly, comprising: a plurality of sprockets, which include at least twelve sprockets with different numbers of teeth, and the at least twelve sprockets are along a rotation center of the bicycle sprocket assembly The axis is arranged coaxially, the entire gear range of one of the plurality of sprockets is equal to or greater than 360%, the average percentage gear level of one of the plurality of sprockets is equal to or greater than 10%, and the average percentage gear level of the plurality of sprockets is equal to or greater than 10%. Less than 15%, the difference between a maximum value of an individual percentage gear level and a minimum value of the individual percentage gear level is greater than half of the average percentage gear level. Such as the bicycle sprocket assembly of claim 1, wherein the average percentage gear level of the plurality of sprockets is in the range of 12% to 14%. For example, the bicycle sprocket assembly of claim 1, wherein the plurality of sprocket wheels includes a first sprocket, the first sprocket includes a first sprocket body and a radially outwardly extending sprocket from the first sprocket body A plurality of first sprocket teeth, the plurality of first sprocket teeth including at least one first tooth and at least one second tooth, the at least one first tooth having a first maximum axial width, and the at least one second tooth It has a second maximum axial width, and the first maximum axial width is greater than the second maximum axial width. Such as the bicycle sprocket assembly of claim 3, where The first sprocket has a first pitch circle diameter which is the largest among the plurality of sprockets. For example, the bicycle sprocket assembly of claim 1, wherein the plurality of sprockets includes an inner space, the inner space includes a first end opening and a second end opening, and the inner space is located at the center of rotation along the axis of rotation. Extending between the first end opening and the second end opening. For example, the bicycle sprocket assembly of claim 5, wherein the first end opening has a first inner diameter, the second end opening has a second inner diameter, and the first inner diameter is larger than the second inner diameter. For example, the bicycle sprocket assembly of claim 1, which further includes a hub engagement member attached to the plurality of sprockets to be engaged with a bicycle hub assembly, wherein the hub engagement member includes an internal thread, the inner The thread is configured to engage with an external thread of the bicycle hub assembly. For example, the bicycle sprocket assembly of claim 1, wherein the plurality of sprockets includes a smallest sprocket, the smallest sprocket has a pitch diameter, which is the smallest among the plurality of sprockets, and A total number of teeth is equal to or less than 10. For example, the bicycle sprocket assembly of claim 1, wherein the plurality of sprocket wheels includes a largest sprocket, the largest sprocket has a circle diameter, which is the largest among the plurality of sprocket wheels, and a total number of teeth is equal to or greater than 36. A bicycle transmission system, comprising: a bicycle sprocket assembly, which includes: a plurality of sprockets, which include at least twelve sprockets with different numbers of teeth, the at least twelve sprockets along the bicycle The rotation center axis of a sprocket assembly is coaxially arranged, the entire gear range of one of the plurality of sprocket wheels is equal to or greater than 360%, the average percentage gear level of one of the plurality of sprocket wheels is equal to or greater than 10%, and the plurality of chains The average percentage gear level of the wheel is less than 15%, the difference between a maximum value of a specific percentage gear level and a minimum value of the individual percentage gear level is greater than half of the average percentage gear level, and a A bicycle rear derailleur, which includes: a base member configured to be mounted to a bicycle frame; a movable member movably coupled to the base member; and a chain guide member coupled to the base member The movable part is used for rotating around a rotation axis of a pivot shaft; a resistance applying element which applies resistance to the rotational movement of one of the chain guides. For example, the bicycle transmission system of claim 10, wherein the bicycle rear derailleur further includes a linkage group interconnecting the base member and the movable member to allow the movable member to be relative to one of the base members Move, and the connecting rod group includes a connecting rod group axis, and the connecting rod group axis is oriented orthogonally to a direction parallel to the rotation center axis of the bicycle sprocket assembly. A bicycle transmission system, comprising: a bicycle rear sprocket assembly, which includes: a plurality of sprockets, which include at least twelve sprockets with different numbers of teeth, the at least twelve sprockets along the The rotation center axis of a bicycle sprocket assembly is coaxially arranged, the entire gear range of one of the plurality of sprockets is equal to or greater than 360%, the average percentage gear level of one of the plurality of sprockets is equal to or greater than 10%, and the plurality of sprockets is equal to or greater than 10%. The average percentage gear level of the sprocket is less than 15%, the difference between a maximum value of a specific percentage gear level and a minimum value of the individual percentage gear level is greater than half of the average percentage gear level, and A bicycle crank assembly, which includes a single front sprocket.

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