Bicycle  rear sprocket assembly

A bicycle rear sprocket assembly comprises a plurality of sprockets and a sprocket carrier. The plurality of sprockets includes a first sprocket and a second sprocket. The first sprocket has at least one circumferential coupling point. The first sprocket is coupled to a radially extending surface of at least one of a plurality of sprocket mounting portions at the at least one circumferential coupling point. The second sprocket has at least one additional circumferential coupling point. The second sprocket is coupled, at the at least one additional circumferential coupling point, to at least one of the sprocket carrier and one of the plurality of sprockets. A total number of the at least one circumferential coupling point is different from a total number of the at least one additional circumferential coupling point.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a bicycle rear sprocket assembly.

Discussion of the Background

Bicycling is becoming an increasingly more popular form of recreation as well as a means of transportation. Moreover, bicycling has become a very popular competitive sport for both amateurs and professionals. Whether the bicycle is used for recreation, transportation or competition, the bicycle industry is constantly improving the various components of the bicycle. One bicycle component that has been extensively redesigned is a sprocket.

SUMMARY OF THE INVENTION

In accordance with a first aspect of the present invention, a bicycle rear sprocket assembly comprises a plurality of sprockets and a sprocket carrier. The plurality of sprockets includes a first sprocket and a second sprocket. The sprocket carrier includes a plurality of sprocket mounting portions. At least one of the plurality of sprocket mounting portions has a radially extending surface and an axially extending surface. The radially extending surface extends radially with respect to a rotational center axis of the bicycle rear sprocket assembly. The axially extending surface extends axially from the radially extending surface with respect to the rotational center axis. The first sprocket has at least one circumferential coupling point. The first sprocket is coupled to the radially extending surface of at least one of the plurality of sprocket mounting portions at the at least one circumferential coupling point. The second sprocket has at least one additional circumferential coupling point. The second sprocket is coupled, at the at least one additional circumferential coupling point, to at least one of the sprocket carrier and one of the plurality of sprockets. A total number of the at least one circumferential coupling point being different from a total number of the at least one additional circumferential coupling point.

With the bicycle rear sprocket assembly according to the first aspect, it is possible to save a weight of the bicycle rear sprocket assembly while improving a balance of rigidity of the bicycle rear sprocket assembly.

In accordance with a second aspect of the present invention, the bicycle rear sprocket assembly according to the first aspect is configured so that the total number of the at least one additional circumferential coupling point is larger than the total number of the at least one circumferential coupling point.

With the bicycle rear sprocket assembly according to the second aspect, it is possible to save the weight of the bicycle rear sprocket assembly while further improving the balance of rigidity of the bicycle rear sprocket assembly.

In accordance with a third aspect of the present invention, the bicycle rear sprocket assembly according to the first or to the second aspect is configured so that the first sprocket has a maximum tooth bottom diameter. The second sprocket has an additional maximum tooth bottom diameter that is larger than the maximum tooth bottom diameter of the first sprocket.

With the bicycle rear sprocket assembly according to the third aspect, it is possible to save the weight of the bicycle rear sprocket assembly while improving the balance of rigidity of the bicycle rear sprocket assembly on a side of a larger sprocket.

In accordance with a fourth aspect of the present invention, the bicycle rear sprocket assembly according to any one of the first to third aspects is configured so that the plurality of sprocket mounting portions each has the radially extending surface extending radially with respect to the rotational center axis, and the axially extending surface extending axially from the radially extending surface with respect to the rotational center axis.

With the bicycle rear sprocket assembly according to the fourth aspect, it is possible to save the weight of the bicycle rear sprocket assembly while further improving the balance of rigidity of the bicycle rear sprocket assembly.

In accordance with a fifth aspect of the present invention, the bicycle rear sprocket assembly according to any one of the first to fourth aspects further comprises at least one fastening member. The first sprocket is coupled to the radially extending surface of the at least one of the plurality of sprocket mounting portions at the at least one circumferential coupling point with the at least one fastening member.

With the bicycle rear sprocket assembly according to the fifth aspect, it is possible to further improve the rigidity of the bicycle rear sprocket assembly.

In accordance with a sixth aspect of the present invention, the bicycle rear sprocket assembly according to any one of the first to fifth aspects further comprises a plurality of fastening members. The at least one circumferential coupling point includes a plurality of circumferential coupling points. The first sprocket is coupled to the radially extending surface of the at least one of the plurality of sprocket mounting portions at the plurality of circumferential coupling points with the plurality of fastening members.

With the bicycle rear sprocket assembly according to the sixth aspect, it is possible to further improve the rigidity of the bicycle rear sprocket assembly.

In accordance with a seventh aspect of the present invention, the bicycle rear sprocket assembly according to any one of the first to sixth aspects is configured so that the second sprocket is coupled to the one of the plurality of sprockets at the at least one additional circumferential coupling point.

With the bicycle rear sprocket assembly according to the seventh aspect, it is possible to further save the weight of the bicycle rear sprocket assembly.

In accordance with an eighth aspect of the present invention, the bicycle rear sprocket assembly according to the seventh aspect further comprises at least one fastening member. The second sprocket is coupled to the one of the plurality of sprockets at the at least one additional circumferential coupling point with the at least one fastening member.

With the bicycle rear sprocket assembly according to the eighth aspect, it is possible to further save the weight of the bicycle rear sprocket assembly.

In accordance with a ninth aspect of the present invention, the bicycle rear sprocket assembly according to the seventh aspect further comprises a plurality of fastening members. The at least one additional circumferential coupling point includes a plurality of additional circumferential coupling points. The second sprocket is coupled to the one of the plurality of sprockets at the plurality of additional circumferential coupling points with the plurality of fastening members.

With the bicycle rear sprocket assembly according to the ninth aspect, it is possible to further save the weight of the bicycle rear sprocket assembly. It is also possible to improve the rigidity of the bicycle rear sprocket assembly.

In accordance with a tenth aspect of the present invention, the bicycle rear sprocket assembly according to any one of the first to sixth aspects is configured so that the second sprocket is coupled to the sprocket carrier at the at least one additional circumferential coupling point.

With the bicycle rear sprocket assembly according to the tenth aspect, it is possible to further improve the rigidity of the bicycle rear sprocket assembly.

In accordance with an eleventh aspect of the present invention, the bicycle rear sprocket assembly according to the tenth aspect further comprises at least one fastening member. The second sprocket is coupled to the sprocket carrier at the at least one additional circumferential coupling point with the at least one fastening member.

With the bicycle rear sprocket assembly according to the eleventh aspect, it is possible to further improve the rigidity of the bicycle rear sprocket assembly.

In accordance with a twelfth aspect of the present invention, the bicycle rear sprocket assembly according to the tenth aspect further comprises a plurality of fastening members. The at least one additional circumferential coupling point includes a plurality of additional circumferential coupling points. The second sprocket is coupled to the sprocket carrier at the plurality of additional circumferential coupling points with the plurality of fastening members.

With the bicycle rear sprocket assembly according to the twelfth aspect, it is possible to further improve the rigidity of the bicycle rear sprocket assembly.

In accordance with a thirteenth aspect of the present invention, the bicycle rear sprocket assembly according to any one of the first to twelfth aspects is configured so that the sprocket carrier includes a central portion and a plurality of sprocket mounting arms extends radially outwardly from the central portion with respect to the rotational center axis. The plurality of sprocket mounting portions is respectively provided to the plurality of sprocket mounting arms. The total number of the plurality of additional circumferential coupling points is larger than a total number of the plurality of sprocket mounting portions.

With the bicycle rear sprocket assembly according to the thirteenth aspect, it is possible to save the weight of the bicycle rear sprocket assembly while further improving the balance of rigidity of the bicycle rear sprocket assembly.

In accordance with a fourteenth aspect of the present invention, the bicycle rear sprocket assembly according to the thirteenth aspect is configured so that the central portion of the sprocket carrier has a hub engagement profile.

With the bicycle rear sprocket assembly according to the fourteenth aspect, it is possible to effectively transmit a driving force to a wheel.

In accordance with a fifteenth aspect of the present invention, the bicycle rear sprocket assembly according to any one of the first to fourteenth aspects is configured so that the plurality of sprockets further includes a third sprocket and a fourth sprocket.

With the bicycle rear sprocket assembly according to the fifteenth aspect, it is possible to save the weight of the bicycle rear sprocket assembly while further improving the balance of rigidity of the bicycle rear sprocket assembly in a multiple rear sprocket assembly.

In accordance with a sixteenth aspect of the present invention, the bicycle rear sprocket assembly according to any one of the first to fifteenth aspects is configured so that the first sprocket is made of titanium.

With the bicycle rear sprocket assembly according to the sixteenth aspect, it is possible to save the weight of the bicycle rear sprocket assembly while further improving the balance of rigidity of the bicycle rear sprocket assembly.

In accordance with a seventeenth aspect of the present invention, the bicycle rear sprocket assembly according to any one of the first to sixteenth aspect is configured so that the second sprocket is made of aluminum.

With the bicycle rear sprocket assembly according to the seventeenth aspect, it is possible to save the weight of the bicycle rear sprocket assembly while further improving the balance of rigidity of the bicycle rear sprocket assembly.

In accordance with an eighteenth aspect of the present invention, the bicycle rear sprocket assembly according to any one of the first to seventeenth aspects is configured so that the plurality of sprocket mounting portions is offset from each other in a radial direction with respect to the rotational center axis.

With the bicycle rear sprocket assembly according to the eighteenth aspect, it is possible to effectively arrange the plurality of sprockets on the sprocket carrier.

In accordance with a nineteenth aspect of the present invention, the bicycle rear sprocket assembly according to any one of the first to eighteenth aspects is configured so that the total number of the at least one additional circumferential coupling point is double of the total number of the at least one circumferential coupling point.

With the bicycle rear sprocket assembly according to the nineteenth aspect, it is possible to save the weight of the bicycle rear sprocket assembly while further improving the balance of rigidity of the bicycle rear sprocket assembly.

In accordance with a twentieth aspect of the present invention, a bicycle rear sprocket assembly comprises a first sprocket wheel, a second sprocket wheel, a third sprocket wheel, at least one fastener, and a sprocket carrier. The first sprocket wheel has a first maximum tooth bottom diameter. The second sprocket wheel has a second maximum tooth bottom diameter that is smaller than the first maximum tooth bottom diameter of the first sprocket wheel. The third sprocket wheel has a third maximum tooth bottom diameter that is larger than the first maximum tooth bottom diameter of the first sprocket wheel. The sprocket carrier includes a central portion and a plurality of sprocket mounting arms extending radially outwardly from the central portion with respect to a rotational center axis of the bicycle rear sprocket assembly. The sprocket carrier includes a first circumferential sprocket-mounting portion and a second circumferential sprocket-mounting portion. The first circumferential sprocket-mounting portion is provided to the plurality of sprocket mounting arms. The second circumferential sprocket-mounting portion is provided to the plurality of sprocket mounting arms and disposed radially inwardly from the first circumferential sprocket-mounting portion with respect to the rotational center axis. The first circumferential sprocket-mounting portion is configured to support the first sprocket wheel. The second circumferential sprocket-mounting portion is configured to support the second sprocket wheel. The third sprocket wheel is configured to be coupled to the first sprocket wheel with the at least one fastener. The first sprocket wheel is disposed between the second sprocket wheel and the third sprocket wheel in an axial direction with respect to the rotational center axis. The twentieth aspect of the present invention can be combined with any one of the first to nineteenth aspects.

With the bicycle rear sprocket assembly according to the twentieth aspect, it is possible to save a weight of the bicycle rear sprocket assembly in a multiple rear sprocket assembly.

In accordance with a twenty-first aspect of the present invention, the bicycle rear sprocket assembly according to the twentieth aspect is configured so that the first circumferential sprocket-mounting portion has a first radially extending surface extending radially with respect to the rotational center axis, and a first axially extending surface extending axially with respect to the rotational center axis. The second circumferential sprocket-mounting portion has a second radially extending surface extending radially with respect to the rotational center axis, and a second axially extending surface extending axially with respect to the rotational center axis.

With the bicycle rear sprocket assembly according to the twenty-first aspect, it is possible to improve the rigidity of the bicycle rear sprocket assembly in the multiple rear sprocket assembly.

In accordance with a twenty-second aspect of the present invention, the bicycle rear sprocket assembly according to the twentieth or twenty-first aspect further comprises at least one first fastener and at least one second fastener. The first sprocket wheel has at least one first circumferential coupling point and is coupled to the first circumferential sprocket-mounting portion at the at least one first circumferential coupling point with the at least one first fastener. The second sprocket wheel has at least one second circumferential coupling point and is coupled to the second circumferential sprocket-mounting portion at the at least one second circumferential coupling point with the at least one second fastener.

With the bicycle rear sprocket assembly according to the twenty-second aspect, it is possible to save the weight of the bicycle rear sprocket assembly in the multiple rear sprocket assembly while improving the rigidity of the bicycle rear sprocket assembly in the multiple rear sprocket assembly.

In accordance with a twenty-third aspect of the present invention, the bicycle rear sprocket assembly according to any one of the twentieth to twenty-second aspects further comprises at least one additional fastener and a fourth sprocket wheel configured to be mounted to the third sprocket wheel with the at least one additional fastener. The third sprocket wheel is disposed between the first sprocket wheel and the fourth sprocket wheel in the axial direction.

With the bicycle rear sprocket assembly according to the twenty-third aspect, it is possible to save the weight of the bicycle rear sprocket assembly in the multiple rear sprocket assembly while improving the rigidity of the bicycle rear sprocket assembly in the multiple rear sprocket assembly.

In accordance with a twenty-fourth aspect of the present invention, the bicycle rear sprocket assembly according to any one of the twentieth aspect to the twenty-third aspect is configured so that the central portion of the sprocket carrier has a hub engagement profile.

With the bicycle rear sprocket assembly according to the twenty-fourth aspect, it is possible to effectively transmit a driving force to a wheel.

In accordance with a twenty-fifth aspect of the present invention, the bicycle rear sprocket assembly according to any one of the twentieth to twenty-fourth aspects is configured so that the first sprocket wheel has at least one first circumferential coupling point and is coupled to the first circumferential sprocket-mounting portion at the at least one first circumferential coupling point. The second sprocket wheel has at least one second circumferential coupling point and is coupled to the second circumferential sprocket-mounting portion at the at least one second circumferential coupling point. A total number of the at least one second circumferential coupling point is equal to or larger than a total number of the at least one first circumferential coupling point. The third sprocket wheel has at least one third circumferential coupling point and is coupled to the first sprocket wheel at the at least one third circumferential coupling point. A total number of the at least one third circumferential coupling point is larger than the total number of the at least one first circumferential coupling point.

With the bicycle rear sprocket assembly according to the twenty-fifth aspect, it is possible to save the weight of the bicycle rear sprocket assembly while further improving the balance of rigidity of the bicycle rear sprocket assembly.

In accordance with a twenty-sixth aspect of the present invention, the bicycle rear sprocket assembly according to the twenty-fifth aspect is configured so that the total number of the at least one third circumferential coupling point is double of the total number of the at least one first circumferential coupling point.

With the bicycle rear sprocket assembly according to the twenty-sixth aspect, it is possible to save the weight of the bicycle rear sprocket assembly while further improving the balance of rigidity of the bicycle rear sprocket assembly.

DESCRIPTION OF THE EMBODIMENTS

First Embodiment

Referring initially toFIG. 1, a bicycle rear sprocket assembly10in accordance with a first embodiment comprises a plurality of sprockets SP. The plurality of sprockets SP includes a first sprocket SP1and a second sprocket SP2. The plurality of sprockets SP further includes a third sprocket SP3and a fourth sprocket SP4. The plurality of sprockets SP further includes fifth to twelfth sprockets SP5to SP12. In this embodiment, the first to twelfth sprockets SP1to SP12can also be referred to as sprockets SP1to SP12, respectively. The third sprocket SP3can be any sprocket selected from the plurality of sprockets SP3to SP12other than the sprocket SP1and the sprocket SP2. The fourth sprocket SP4can be any sprocket selected from the plurality of sprockets SP3to SP12other than the sprocket SP1, the sprocket SP2and a sprocket selected as the sprocket SP3.

The first sprocket SP1can also be referred to as a first sprocket wheel SP1. The second sprocket SP2can also be referred to as a third sprocket wheel SP2. The third sprocket SP3can also be referred to as a forth sprocket wheel SP3. The fourth sprocket SP4can also be referred to as a second sprocket wheel SP4. Namely, the bicycle rear sprocket assembly10comprises the first sprocket wheel SP1, the second sprocket wheel SP4, and the third sprocket wheel SP2. The bicycle rear sprocket assembly10further comprises the fourth sprocket wheel SP3. The first sprocket wheel SP1can also be referred to as the sprocket SP1. The second sprocket wheel SP4can also be referred to as the sprocket SP4. The third sprocket wheel SP2can also be referred to as the sprocket SP2. The fourth sprocket wheel SP3can also be referred to as the sprocket SP3. A total number of the sprockets SP1to SP12is not limited to this embodiment.

As seen inFIG. 1, the bicycle rear sprocket assembly10has a rotational center axis A1. The bicycle rear sprocket assembly10is rotatably supported by a bicycle rear hub assembly H relative to a bicycle frame (not shown) about the rotational center axis A1. The bicycle rear sprocket assembly10is secured to a sprocket support body of the bicycle rear hub assembly with a lock member H1. The bicycle rear sprocket assembly10is configured to be engaged with a bicycle chain C to transmit a driving rotational force F1between the bicycle chain C and the bicycle rear sprocket assembly10during pedaling. The bicycle rear sprocket assembly10is rotated about the rotational center axis A1in a driving rotational direction D11during pedaling. The driving rotational direction D11is defined along a circumferential direction D1with respect to the rotational center axis A1of the bicycle rear sprocket assembly10. A reverse rotational direction D12is an opposite direction of the driving rotational direction D11and is defined along the circumferential direction D1.

In this embodiment, the sprocket SP3is the largest sprocket in the bicycle rear sprocket assembly10. The twelfth sprocket SP12is the smallest sprocket in the bicycle rear sprocket assembly10. The first sprocket SP1has a maximum tooth bottom diameter TD1. The maximum tooth bottom diameter TD1can also be referred to as a first maximum tooth bottom diameter TD1. Namely, the first sprocket wheel SP1has the first maximum tooth bottom diameter TD1. The second sprocket SP2has an additional maximum tooth bottom diameter TD2that is larger than the maximum tooth bottom diameter TD1of the first sprocket SP1. The additional maximum tooth bottom diameter TD2can also be referred to as a third maximum tooth bottom diameter TD2. Namely, the third sprocket wheel SP2has the third maximum tooth bottom diameter TD2that is larger than the first maximum tooth bottom diameter TD1of the first sprocket wheel SP1. The second sprocket wheel SP4has a second maximum tooth bottom diameter TD4that is smaller than the first maximum tooth bottom diameter TD1of the first sprocket wheel SP1. The third sprocket SP3has an additional maximum tooth bottom diameter TD3that is larger than the maximum tooth bottom diameter TD1of the first sprocket SP1. The sprockets SP5to SP12respectively have fifth to twelfth maximum tooth bottom diameter TD5to TD12.

The dimensional relationship among the sprockets SP1to SP12is not limited to this embodiment. For example, the additional maximum tooth bottom diameter TD2can be equal to or smaller than the maximum tooth bottom diameter TD1of the first sprocket SP1. The second maximum tooth bottom diameter TD4can be equal to or larger than the first maximum tooth bottom diameter TD1of the first sprocket wheel SP1.

As seen inFIG. 2, the first sprocket wheel SP1is disposed between the second sprocket wheel SP4and the third sprocket wheel SP2in an axial direction D2with respect to the rotational center axis A1. The third sprocket wheel SP2is disposed between the first sprocket wheel SP1and the fourth sprocket wheel SP3in the axial direction D2. The second sprocket SP2is adjacent to the first sprocket SP1without another sprocket between the first sprocket SP1and the second sprocket SP2in the axial direction D2with respect to the rotational center axis A1of the bicycle rear sprocket assembly10. The third sprocket SP3is adjacent to the second sprocket SP2without another sprocket between the second sprocket SP2and the third sprocket SP3in the axial direction D2with respect to the rotational center axis A1of the bicycle rear sprocket assembly10. The fourth sprocket SP4is adjacent to the first sprocket SP1without another sprocket between the first sprocket SP1and the fourth sprocket SP4in the axial direction D2with respect to the rotational center axis A1of the bicycle rear sprocket assembly10. The third sprocket SP3, the second sprocket SP2, the first sprocket SP1, and the fourth to twelfth sprockets SP4to SP12are arranged in the axial direction D2in this order.

In this embodiment, the sprockets SP1to SP12are separate members from each other. However, at least two of the sprockets SP1to SP12can be at least partly provided integrally with each other. Specifically, at least two of the sprockets SP1to SP12can be integrally provided as a unitary, one-piece member. Alternatively, at least two of the sprockets SP1to SP12can be connected to each other with at least one mechanical fastener such as a rivet, or with adhesive, diffusion bonding and so on. The sprockets SP1to SP12are made of a metallic material. In this embodiment, the first sprocket SP1is made of titanium. The second sprocket SP2is made of aluminum. The third sprocket SP3is made of aluminum. The fourth sprocket SP4is made of titanium. However, materials of the first to twelfth sprockets SP1to SP12is not limited to this embodiment. At least one of the sprockets SP1to SP12can be made of another metallic material or a non-metallic material.

As seen inFIG. 3, the first sprocket SP1includes a sprocket body SP1A and a plurality of sprocket teeth SP1B. The plurality of sprocket teeth SP1B extends radially outwardly from the sprocket body SP1A with respect to the rotational center axis A1of the bicycle rear sprocket assembly10. A total tooth number of the first sprocket SP1(a total number of the at least one sprocket teeth SP1B) is 39. However, the total number of the plurality of sprocket tooth SP1B of the first sprocket SP1is not limited to this embodiment.

The first sprocket SP1includes a plurality of tooth bottoms SP1C. The tooth bottom SP1C is provided between adjacent two of the sprocket teeth SP1B. The plurality of tooth bottoms SP1C defines a root circle RC1having the maximum tooth bottom diameter TD1. The term “maximum tooth bottom diameter”, as used herein, is intended to be a diameter of a root circle defined by tooth bottoms if shapes of all of the toot bottoms are identical with each other, or to be a diameter of a maximum root circle defined by at least one tooth bottom if tooth bottoms having several shapes are provided in one sprocket so that a plurality of root circles are defined in the sprocket. The term definition can be applied to any sprocket in the first to twelfth sprockets SP1to SP12.

As seen inFIG. 4, the second sprocket SP2includes a sprocket body SP2A and a plurality of sprocket teeth SP2B. The plurality of sprocket teeth SP2B extends radially outwardly from the sprocket body SP2A with respect to the rotational center axis A1of the bicycle rear sprocket assembly10. A total tooth number of the second sprocket SP2(a total number of the at least one sprocket teeth SP2B) is 45. However, the total number of the plurality of sprocket tooth SP2B of the second sprocket SP2is not limited to this embodiment.

The second sprocket SP2includes a plurality of tooth bottoms SP2C. The tooth bottom SP2C is provided between adjacent two of the sprocket teeth SP2B. The plurality of tooth bottoms SP2C defines a root circle RC2having the maximum tooth bottom diameter TD2.

As seen inFIG. 5, the third sprocket SP3includes a sprocket body SP3A and a plurality of sprocket teeth SP3B. The plurality of sprocket teeth SP3B extends radially outwardly from the sprocket body SP3A with respect to the rotational center axis A1of the bicycle rear sprocket assembly10. A total tooth number of the third sprocket SP3(a total number of the at least one sprocket teeth SP3B) is 51. However, the total number of the plurality of sprocket tooth SP3B of the third sprocket SP3is not limited to this embodiment.

The third sprocket SP3includes a plurality of tooth bottoms SP3C. The tooth bottom SP3C is provided between adjacent two of the sprocket teeth SP3B. The plurality of tooth bottoms SP3C defines a root circle RC3having the maximum tooth bottom diameter TD3.

As seen inFIG. 6, the fourth sprocket SP4includes a sprocket body SP4A and a plurality of sprocket teeth SP4B. The plurality of sprocket teeth SP4B extends radially outwardly from the sprocket body SP4A with respect to the rotational center axis A1of the bicycle rear sprocket assembly10. A total tooth number of the fourth sprocket SP4(a total number of the at least one sprocket teeth SP4B) is 33. However, the total number of the plurality of sprocket tooth SP4B of the fourth sprocket SP4is not limited to this embodiment.

The fourth sprocket SP4includes a plurality of tooth bottoms SP4C. The tooth bottom SP4C is provided between adjacent two of the sprocket teeth SP4B. The plurality of tooth bottoms SP4C defines a root circle RC4having the maximum tooth bottom diameter TD4.

As seen inFIG. 7, the fifth sprocket SP5includes a sprocket body SP5A and a plurality of sprocket teeth SP5B. The plurality of sprocket teeth SP5B extends radially outwardly from the sprocket body SP5A with respect to the rotational center axis A1of the bicycle rear sprocket assembly10. A total tooth number of the fifth sprocket SP5(a total number of the at least one sprocket teeth SP5B) is 28. However, the total number of the plurality of sprocket tooth SP5B of the fifth sprocket SP5is not limited to this embodiment.

The fifth sprocket SP5includes a plurality of tooth bottoms SP5C. The tooth bottom SP5C is provided between adjacent two of the sprocket teeth SP5B. The plurality of tooth bottoms SP5C defines a root circle RC5having the maximum tooth bottom diameter TD5.

As seen inFIG. 8, the sixth sprocket SP6includes a sprocket body SP6A and a plurality of sprocket teeth SP6B. The plurality of sprocket teeth SP6B extends radially outwardly from the sprocket body SP6A with respect to the rotational center axis A1of the bicycle rear sprocket assembly10. A total tooth number of the sixth sprocket SP6(a total number of the at least one sprocket teeth SP6B) is 24. However, the total number of the plurality of sprocket tooth SP6B of the sixth sprocket SP6is not limited to this embodiment.

The sixth sprocket SP6includes a plurality of tooth bottoms SP6C. The tooth bottom SP6C is provided between adjacent two of the sprocket teeth SP6B. The plurality of tooth bottoms SP6C defines a root circle RC6having the maximum tooth bottom diameter TD6.

As seen inFIG. 9, the seventh sprocket SP7includes a sprocket body SP7A and a plurality of sprocket teeth SP7B. The plurality of sprocket teeth SP7B extends radially outwardly from the sprocket body SP7A with respect to the rotational center axis A1of the bicycle rear sprocket assembly10. A total tooth number of the seventh sprocket SP7(a total number of the at least one sprocket teeth SP7B) is 21. However, the total number of the plurality of sprocket tooth SP7B of the seventh sprocket SP7is not limited to this embodiment.

The seventh sprocket SP7includes a plurality of tooth bottoms SP7C. The tooth bottom SP7C is provided between adjacent two of the sprocket teeth SP7B. The plurality of tooth bottoms SP7C defines a root circle RC7having the maximum tooth bottom diameter TD7.

As seen inFIG. 10, the eighth sprocket SP8includes a sprocket body SP8A and a plurality of sprocket teeth SP8B. The plurality of sprocket teeth SP8B extends radially outwardly from the sprocket body SP8A with respect to the rotational center axis A1of the bicycle rear sprocket assembly10. A total tooth number of the eighth sprocket SP8(a total number of the at least one sprocket teeth SP8B) is 21. However, the total number of the plurality of sprocket tooth SP8B of the eighth sprocket SP8is not limited to this embodiment.

The eighth sprocket SP8includes a plurality of tooth bottoms SP8C. The tooth bottom SP8C is provided between adjacent two of the sprocket teeth SP8B. The plurality of tooth bottoms SP8C defines a root circle RC8having the maximum tooth bottom diameter TDB.

As seen inFIG. 11, the ninth sprocket SP9includes a sprocket body SP9A and a plurality of sprocket teeth SP9B. The plurality of sprocket teeth SP9B extends radially outwardly from the sprocket body SP9A with respect to the rotational center axis A1of the bicycle rear sprocket assembly10. A total tooth number of the ninth sprocket SP9(a total number of the at least one sprocket teeth SP9B) is 16. However, the total number of the plurality of sprocket tooth SP9B of the ninth sprocket SP9is not limited to this embodiment.

The ninth sprocket SP9includes a plurality of tooth bottoms SP9C. The tooth bottom SP9C is provided between adjacent two of the sprocket teeth SP9B. The plurality of tooth bottoms SP9C defines a root circle RC9having the maximum tooth bottom diameter TD9.

As seen inFIG. 12, the tenth sprocket SP10includes a sprocket body SP10A and a plurality of sprocket teeth SP10B. The plurality of sprocket teeth SP1OB extends radially outwardly from the sprocket body SP10A with respect to the rotational center axis A1of the bicycle rear sprocket assembly10. A total tooth number of the tenth sprocket SP10(a total number of the at least one sprocket teeth SP10B) is 14. However, the total number of the plurality of sprocket tooth SP1OB of the tenth sprocket SP10is not limited to this embodiment.

The tenth sprocket SP10includes a plurality of tooth bottoms SP10C. The tooth bottom SP10C is provided between adjacent two of the sprocket teeth SP10B. The plurality of tooth bottoms SP10C defines a root circle RC10having the maximum tooth bottom diameter TD10.

As seen inFIG. 13, the eleventh sprocket SP11includes a sprocket body SP11A and a plurality of sprocket teeth SP11B. The plurality of sprocket teeth SP11B extends radially outwardly from the sprocket body SP11A with respect to the rotational center axis Al of the bicycle rear sprocket assembly10. A total tooth number of the eleventh sprocket SP11(a total number of the at least one sprocket teeth SP11B) is 12. However, the total number of the plurality of sprocket tooth SP11B of the eleventh sprocket SP11is not limited to this embodiment.

The eleventh sprocket SP11includes a plurality of tooth bottoms SP11C. The tooth bottom SP11C is provided between adjacent two of the sprocket teeth SP11B. The plurality of tooth bottoms SP11C defines a root circle RC11having the maximum tooth bottom diameter TD11.

As seen inFIG. 14, the twelfth sprocket SP12includes a sprocket body SP12A and a plurality of sprocket teeth SP12B. The plurality of sprocket teeth SP12B extends radially outwardly from the sprocket body SP12A with respect to the rotational center axis Al of the bicycle rear sprocket assembly10. A total tooth number of the twelfth sprocket SP12(a total number of the at least one sprocket teeth SP12B) is 10. However, the total number of the plurality of sprocket tooth SP12B of the twelfth sprocket SP12is not limited to this embodiment.

The twelfth sprocket SP12includes a plurality of tooth bottoms SP12C. The tooth bottom SP12C is provided between adjacent two of the sprocket teeth SP12B. The plurality of tooth bottoms SP12C defines a root circle RC12having the maximum tooth bottom diameter TD12.

As seen inFIG. 15, the bicycle rear sprocket assembly10comprises a sprocket carrier12. The sprocket carrier12is a separate member from the plurality of sprockets SP. As seen inFIG. 2, the sprockets SP1and SP4to SP8are attached to the sprocket carrier12. In this embodiment, the sprocket carrier12is made of aluminum. However, the sprocket carrier12can be made of a metallic material other than aluminum or a non-metallic material such as fiber reinforced plastics.

As seen inFIG. 16, the sprocket carrier12includes a plurality of sprocket mounting portions14A to14E. At least one of the plurality of sprocket mounting portions14A to14E has a radially extending surface16and an axially extending surface18. In this embodiment, the plurality of sprocket mounting portions14A to14E each has the radially extending surface16and the axially extending surface18. The sprocket mounting portion14A has the radially extending surface16A and the axially extending surface18A. The sprocket mounting portion14B has the radially extending surface16B and the axially extending surface18B. The sprocket mounting portion14C has the radially extending surface16C and the axially extending surface18C. The sprocket mounting portion14D has the radially extending surface16D and the axially extending surface18D. The sprocket mounting portion14E has the radially extending surface16E and the axially extending surface18E.

The radially extending surface16A extends radially with respect to the rotational center axis A1of the bicycle rear sprocket assembly10. The axially extending surface18A extends axially from the radially extending surface16A with respect to the rotational center axis A1. The radially extending surface16B extends radially with respect to the rotational center axis A1of the bicycle rear sprocket assembly10. The axially extending surface18B extends axially from the radially extending surface16B with respect to the rotational center axis A1. The radially extending surface16C extends radially with respect to the rotational center axis A1of the bicycle rear sprocket assembly10. The axially extending surface18C extends axially from the radially extending surface16C with respect to the rotational center axis A1. The radially extending surface16D extends radially with respect to the rotational center axis A1of the bicycle rear sprocket assembly10. The axially extending surface18D extends axially from the radially extending surface16D with respect to the rotational center axis A1. The radially extending surface16E extends radially with respect to the rotational center axis A1of the bicycle rear sprocket assembly10. The axially extending surface18E extends axially from the radially extending surface16E with respect to the rotational center axis A1. The radially extending surface16A can also be referred to as a first radially extending surface16A. The axially extending surface18A can also be referred to as a first axially extending surface18A. The radially extending surface16B can also be referred to as a second radially extending surface16B. The axially extending surface18B can also be referred to as a second axially extending surface18B.

In other words, the sprocket carrier12includes a first circumferential sprocket-mounting portion19A and a second circumferential sprocket-mounting portion19B. The first circumferential sprocket-mounting portion19A is provided to the plurality of sprocket mounting arms22. The second circumferential sprocket-mounting portion19B is provided to the plurality of sprocket mounting arms22and is disposed radially inwardly from the first circumferential sprocket-mounting portion19A with respect to the rotational center axis A1. The first circumferential sprocket-mounting portion19A is configured to support the first sprocket wheel SP1. The second circumferential sprocket-mounting portion19B is configured to support the second sprocket wheel SP4.

As seen inFIG. 17, the first circumferential sprocket-mounting portion19A has the first radially extending surface16A and the first axially extending surface18A. The first radially extending surface16A extends radially with respect to the rotational center axis A1. The first axially extending surface18(18A) extends axially with respect to the rotational center axis A1. In this embodiment, the first circumferential sprocket-mounting portion19A has a plurality of first radially extending surfaces16A and a plurality of first axially extending surfaces18A.

The second circumferential sprocket-mounting portion19B has the second radially extending surface16B and the second axially extending surface18B. The second radially extending surface16B extends radially with respect to the rotational center axisA1. The second axially extending surface18B extends axially with respect to the rotational center axis A1. In this embodiment, the second circumferential sprocket-mounting portion19B has a plurality of second radially extending surfaces16B and a plurality of second axially extending surfaces18B.

As seen inFIG. 17, the plurality of sprocket mounting portions14A to14E is offset from each other in a radial direction with respect to the rotational center axis A1. The sprocket mounting portion14A is radially outwardly of the sprocket mounting portion14B. The sprocket mounting portion14B is radially outwardly of the sprocket mounting portion14C. The sprocket mounting portion14C is radially outwardly of the sprocket mounting portion14D. The sprocket mounting portion14D is radially outwardly of the sprocket mounting portion14E. The sprocket mounting portions14A to14E are arranged along the sprocket mounting arm22. The arrangement of the sprocket mounting portions14A to14E is not limited to this embodiment.

As seen inFIG. 2, in this embodiment, the radially extending surface16is substantially perpendicular to the rotational center axis A1. However, the radially extending surface16can be inclined relative to the rotational center axis A1. In this embodiment, the axially extending surface18is substantially parallel to the rotational center axis A1. However, the axially extending surface18can be inclined relative to the rotational center axis A1. Furthermore, the axially extending surface18is directly connected to the radially extending surface16. However, the axially extending surface18can be spaced apart from the radially extending surface16.

As seen inFIG. 16, the sprocket carrier12includes a central portion21and a plurality of sprocket mounting arms22extends radially outwardly from the central portion21with respect to the rotational center axis A1of the bicycle rear sprocket assembly10. The plurality of sprocket mounting portions14A to14E is respectively provided to the plurality of sprocket mounting arms22. In this embodiment, the sprocket mounting portions14A to14E are provided to the sprocket mounting arm22. However, the arrangement of the sprocket mounting portions14A to14E is not limited to this embodiment.

The central portion21of the sprocket carrier12has a hub engagement profile24. In this embodiment, the hub engagement profile24includes a hub internal spline26. The hub internal spline26includes a plurality of internal spline teeth28configured to engage with a plurality of external spline teeth (not shown) of the bicycle rear hub assembly H (FIG. 2). The hub engagement profile24includes a hub internal spline30. The hub internal spline30includes a plurality of internal spline teeth31configured to engage with the plurality of external spline teeth (not shown) of the bicycle rear hub assembly H (FIG. 2). The hub internal spline30is spaced apart from the hub internal spline26in the axial direction D2. The hub internal spline30can be connected to the hub internal spline26. However, the structure of the hub engagement profile24is not limited to this embodiment. The hub engagement profile24can be omitted from the central portion21of the sprocket carrier12. The hub engagement profile24can include another structure instead of or in addition to the hub internal splines26and30.

As seen inFIG. 18, the bicycle rear sprocket assembly10further comprises at least one fastening member32. In this embodiment, the bicycle rear sprocket assembly10further comprises a plurality of fastening members32. The first sprocket SP1is secured to the sprocket carrier12with the plurality of fastening members32. In this embodiment, a total number of the fastening members32is 6. However, the total number of the fastening members32is not limited to this embodiment. The fastening member32is preferably made of a metallic material such as iron or titanium. The fastening member32can also be made of aluminum. However, the at least one fastening member32can be made of a non-metallic material. In this embodiment, the fastening member32includes a rivet. However, the fastening member32can include another fastener such as adhesive or diffusion bonding instead of or in addition to the rivet.

The bicycle rear sprocket assembly10further comprises at least one fastening member34. The fastening member34can be also referred to as a fastener34. Namely, the bicycle rear sprocket assembly10comprises at least one fastener34. In this embodiment, the bicycle rear sprocket assembly10further comprises a plurality of fastening members (a plurality of fasteners)34. The second sprocket SP2is coupled to the first sprocket SP1with the plurality of fastening members (the plurality of fasteners)34. The third sprocket wheel (the second sprocket) SP2is configured to be coupled to the first sprocket wheel (the first sprocket) SP1with the at least one fastener (the at least one fastening member)34.

The bicycle rear sprocket assembly10further comprises at least one additional fastening member36. The additional fastening member36can also be referred to as an additional fastener36. Namely, the bicycle rear sprocket assembly10further comprises at least one additional fastener36. In this embodiment, the bicycle rear sprocket assembly10further comprises a plurality of additional fastening members (a plurality of additional fasteners)36. The third sprocket SP3is coupled to the second sprocket SP2with the plurality of additional fastening members36.

The bicycle rear sprocket assembly10further comprises at least one additional fastening member38. The fastening member32can be also referred to as a first fastener32. The additional fastening member38can be also referred to as a second fastener38. Namely, the bicycle rear sprocket assembly10further comprises at least one first fastener32and at least one second fastener38. In this embodiment, the bicycle rear sprocket assembly10further comprises a plurality of additional fastening members38. The sprocket SP4is coupled to the sprocket carrier12with the plurality of additional fastening members38.

The bicycle rear sprocket assembly10further comprises at least one additional fastening member40. In this embodiment, the bicycle rear sprocket assembly10further comprises a plurality of additional fastening members40. The sprocket SP5is coupled to the sprocket carrier12with the plurality of additional fastening members40.

The bicycle rear sprocket assembly10further comprises at least one additional fastening member42. In this embodiment, the bicycle rear sprocket assembly10further comprises a plurality of additional fastening members42. The sprocket SP6is coupled to the sprocket carrier12with the plurality of additional fastening members42.

The bicycle rear sprocket assembly10further comprises at least one additional fastening member44. In this embodiment, the bicycle rear sprocket assembly10further comprises a plurality of additional fastening members44. The sprocket SP7is coupled to the sprocket carrier12with the plurality of additional fastening members44.

In this embodiment, a total number of the fastening members34is 6. However, the total number of the fastening members34is not limited to this embodiment. The fastening member34is preferably made of a metallic material such as iron or titanium. The fastening member34can also be made of aluminum. However, the at least one fastening member34can be made of a non-metallic material. In this embodiment, the fastening member34includes a rivet. However, the fastening member34can include another fastener such as adhesive or diffusion bonding instead of or in addition to the rivet.

A total number of the fastening members36is 6. However, the total number of the fastening members36is not limited to this embodiment. The fastening member36is preferably made of a metallic material such as iron or titanium. The fastening member36can also be made of aluminum. However, the at least one fastening member36can be made of a non-metallic material. In this embodiment, the fastening member36includes a rivet. However, the fastening member36can include another fastener such as adhesive or diffusion bonding instead of or in addition to the rivet.

A total number of the additional fastening members38is 6. A total number of the additional fastening members40is 6. A total number of the additional fastening members42is 6. A total number of the additional fastening members44is 6. However, the total number of the additional fastening members is not limited to this embodiment. The material of the additional fastening member is the same as that of the material of the fastening member34and/or36. Thus, they will not be described in detail here for the sake of brevity.

As seen inFIG. 17, the sprocket mounting portion14A includes a mounting hole20A provided on the radially extending surface16A. The sprocket mounting portion14B includes a mounting hole20B provided on the radially extending surface16B. The sprocket mounting portion14C includes a mounting hole20C provided on the radially extending surface16C. The sprocket mounting portion14D includes a mounting hole20D provided on the radially extending surface16D. The sprocket mounting portion14E includes a mounting hole20E provided on the radially extending surface16E. As seen inFIG. 2, the fastening member32extends through the mounting hole20A. The additional fastening member38extends through the mounting hole20B. The additional fastening member40extends through the mounting hole20C. The additional fastening member42extends through the mounting hole20D. The additional fastening member44extends through the mounting hole20E.

As seen inFIG. 3. the first sprocket SP1has at least one circumferential coupling point CP1. The circumferential coupling point CP1can also be referred to as a first circumferential coupling point CP1. Namely, the first sprocket wheel SP1has at least one first circumferential coupling point CP1. In this embodiment, the at least one circumferential coupling point CP1includes a plurality of circumferential coupling points CP1. The circumferential coupling points CP1are spaced apart from each other in the circumferential direction D1. The circumferential coupling points CP1are provided in the same radial position and are provided at a constant pitch in the circumferential direction D1. A total number of the circumferential coupling points CP1is 6. However, the total number of the circumferential coupling points CP1is not limited to this embodiment. The first sprocket SP1includes a plurality of through-holes SP1D. The circumferential coupling point CP1is defined at a center of the through-hole SP1D. As seen inFIG. 2, the fastening member32extends through the through-hole SP1D and the mounting hole20A.

As seen inFIG. 18, the first sprocket SP1is coupled to the radially extending surface16(FIG. 16) of at least one of the plurality of sprocket mounting portions14A to14E at the at least one circumferential coupling point CP1. In this embodiment, the first sprocket SP1is coupled to the plurality of radially extending surfaces16(FIG. 16) of the plurality of sprocket mounting portions14A at the plurality of circumferential coupling points CP1. The first sprocket SP1is coupled to the radially extending surface16(FIG. 16) of the at least one of the plurality of sprocket mounting portions14A to14E at the at least one circumferential coupling point CP1with the at least one fastening member32. The first sprocket SP1is coupled to the radially extending surface16of the at least one of the plurality of sprocket mounting portions14A to14E at the plurality of circumferential coupling points CP1with the plurality of fastening members32. In other words, the first sprocket wheel SP1is coupled to the first circumferential sprocket-mounting portion19A at the at least one first circumferential coupling point CP1. The first sprocket wheel SP1is coupled to the first circumferential sprocket-mounting portion19A at the at least one first circumferential coupling point CP1with the at least one first fastener32. The circumferential coupling point CP1can be defined by the fastening member (the fastener)32.

As seen inFIG. 4, the second sprocket SP2has at least one additional circumferential coupling point CP2. The additional circumferential coupling point CP2can also be referred to as a third circumferential coupling point CP2. Namely, the third sprocket wheel SP2has at least one third circumferential coupling point CP2. In this embodiment, the at least one additional circumferential coupling point CP2includes a plurality of additional circumferential coupling points (a plurality of third circumferential coupling points) CP2. The additional circumferential coupling points CP2are spaced apart from each other in the circumferential direction D1. The additional circumferential coupling points CP2are provided in the same radial position and are provided at a constant pitch in the circumferential direction D1. A total number of the additional circumferential coupling points CP2is 12. However, the total number of the additional circumferential coupling points CP2is not limited to this embodiment. The second sprocket SP2includes a plurality of through-holes SP2D. The additional circumferential coupling point CP2is defined at a center of the through-hole SP2D.

As seen inFIG. 3, the first sprocket SP1includes a plurality of additional through-holes SP1E. The additional circumferential coupling point CP2is defined at a center of the additional through-hole SP1E. The additional through-holes SPIE of the first sprocket SP1are provided at positions corresponding to the through-holes SP2D (FIG. 4) of the second sprocket SP2.

As seen inFIG. 19, the bicycle rear sprocket assembly10comprises a plurality of spacers SC1provided between the sprockets SP1and SP2in the axial direction D2. The spacer SC1includes a spacer hole SC1A. The fastening member34extends through the additional through-hole SP1E, the through-holes SP2D, and the spacer hole SC1A. The spacer SC1can be integrally formed with the fastening member34as a unitary, one-piece member.

As seen inFIG. 18, the second sprocket SP2is coupled, at the at least one additional circumferential coupling point CP2, to at least one of the sprocket carrier12and one of the plurality of sprockets SP1to SP12. In this embodiment, the second sprocket SP2is coupled to the one of the plurality of sprockets SP1to SP12at the at least one additional circumferential coupling point CP2. In this embodiment, the second sprocket SP2is coupled to the first sprocket SP1at the at least one additional circumferential coupling point CP2. In other words, the third sprocket wheel SP2is coupled to the first sprocket wheel SP1at the at least one third circumferential coupling point CP2. However, the second sprocket SP2can be coupled to the one of the plurality of sprockets at another coupling point. The second sprocket SP2can be coupled to the sprocket carrier12.

The second sprocket SP2is coupled to the one of the plurality of sprockets SP1to SP12at the at least one additional circumferential coupling point CP2with the at least one fastening member34. The second sprocket SP2is coupled to the first sprocket SP1at the at least one additional circumferential coupling point CP2with the at least one fastening member34. The second sprocket SP2is coupled to the one of the plurality of sprockets at the plurality of additional circumferential coupling points with the plurality of fastening members34. The second sprocket SP2is coupled to the first sprocket SP1at the plurality of additional circumferential coupling points CP2with the plurality of fastening members34. The additional circumferential coupling point CP2can be defined by the fastening member34.

As seen inFIG. 18, a total number of the at least one circumferential coupling point (the at least one first circumferential coupling point) CP1is different from a total number of the at least one additional circumferential coupling point (the at least one third circumferential coupling point) CP2. In this embodiment, the total number of the at least one additional circumferential coupling point (the at least one third circumferential coupling point) CP2is larger than the total number of the at least one circumferential coupling point (the at least one first circumferential coupling point) CP1. The total number of the circumferential coupling points CP1is 6. The total number of the additional circumferential coupling points CP2is 12. The total number of the at least one additional circumferential coupling point (the at least one third circumferential coupling point) CP2is double of the total number of the at least one circumferential coupling point (the at least one first circumferential coupling point) CP1. The total number of the at least one third circumferential coupling point CP2is double of the total number of the at least one first circumferential coupling point CP1.

However, the relationship between the total number of the at least one circumferential coupling point CP1and the total number of the at least one additional circumferential coupling point CP2is not limited to this embodiment. The total number of the at least one circumferential coupling point CP1can be equal to or larger than the total number of the at least one additional circumferential coupling point CP2. The total number of the circumferential coupling points CP1is not limited to this embodiment. The total number of the additional circumferential coupling points CP2is not limited to this embodiment.

The total number of the plurality of additional circumferential coupling points CP2is larger than a total number of the plurality of sprocket mounting portions14A. The total number of the plurality of additional circumferential coupling points CP2is larger than a total number of the plurality of sprocket mounting arms22. However, the total number of the plurality of additional circumferential coupling points CP2can be equal to or smaller than the total number of the plurality of sprocket mounting portions14A. The total number of the plurality of additional circumferential coupling points CP2can be equal to or smaller than the total number of the plurality of sprocket mounting arms22.

As seen inFIG. 5, the third sprocket SP3has at least one additional circumferential coupling point CP3. In this embodiment, the at least one additional circumferential coupling point CP3includes a plurality of additional circumferential coupling points CP3. The additional circumferential coupling points CP3are spaced apart from each other in the circumferential direction D1. The additional circumferential coupling points CP3are provided in the same radial position and are provided at a constant pitch in the circumferential direction D1. A total number of the additional circumferential coupling points CP3is 12. However, the total number of the additional circumferential coupling points CP3is not limited to this embodiment. The third sprocket SP3includes a plurality of through-holes SP3D. The additional circumferential coupling point CP3is defined at a center of the through-hole SP3D.

As seen inFIG. 4, the second sprocket SP2includes a plurality of additional through-holes SP2E. The additional circumferential coupling point CP3is defined at a center of the additional through-hole SP2E. The additional through-holes SP2E of the second sprocket SP2are provided at positions corresponding to the through-holes SP3D (FIG. 4) of the third sprocket SP3.

As seen inFIG. 19, the bicycle rear sprocket assembly10comprises a plurality of spacers SC2provided between the sprockets SP2and SP3in the axial direction D2. The spacer SC2includes a spacer hole SC2A. The fastening member36extends through the additional through-hole SP2E, the through-holes SP3D, and the spacer hole SC2A. The spacer SC2can be integrally formed with the fastening member36as a unitary, one-piece member.

As seen inFIG. 18, the third sprocket SP3is coupled, at the at least one additional circumferential coupling point CP3, to at least one of the sprocket carrier12and one of the plurality of sprockets SP1to SP12. In this embodiment, the third sprocket SP3is coupled to the one of the plurality of sprockets SP1to SP12at the at least one additional circumferential coupling point CP3. In this embodiment, the third sprocket SP3is coupled to the second sprocket SP2at the at least one additional circumferential coupling point CP3. However, the third sprocket SP3can be coupled to the one of the plurality of sprockets at another coupling point. The third sprocket SP3can be coupled to the sprocket carrier12.

The third sprocket SP3is coupled to the one of the plurality of sprockets SP1to SP12at the at least one additional circumferential coupling point CP3with the at least one additional fastening member36. The third sprocket SP3is coupled to the second sprocket SP2at the at least one additional circumferential coupling point CP3with the at least one additional fastening member36. The third sprocket SP3is coupled to the one of the plurality of sprockets at the plurality of additional circumferential coupling points with the plurality of additional fastening members36. The third sprocket SP3is coupled to the second sprocket SP2at the plurality of additional circumferential coupling points CP3with the plurality of additional fastening members36. In other words, the fourth sprocket wheel SP3is configured to be mounted to the third sprocket wheel SP2with the at least one additional fastener36. The fourth sprocket wheel SP3is configured to be mounted to the third sprocket wheel SP2with the plurality of additional fasteners36. The additional circumferential coupling point CP3can be defined by the additional fastening member (the additional fastener)36.

As seen inFIG. 18, a total number of the at least one circumferential coupling point CP1is different from a total number of the at least one additional circumferential coupling point CP3. In this embodiment, the total number of the at least one circumferential coupling point CP1is smaller than the total number of the at least one additional circumferential coupling point CP3. The total number of the circumferential coupling points CP1is 6. The total number of the additional circumferential coupling points CP3is12. The total number of the at least one additional circumferential coupling point CP3is double of the total number of the at least one circumferential coupling point CP1. However, the relationship between the total number of the at least one circumferential coupling point CP1and the total number of the at least one additional circumferential coupling point CP3is not limited to this embodiment. The total number of the at least one circumferential coupling point CP1can be equal to or larger than the total number of the at least one additional circumferential coupling point CP3. The total number of the circumferential coupling points CP1is not limited to this embodiment. The total number of the additional circumferential coupling points CP3is not limited to this embodiment.

The total number of the plurality of additional circumferential coupling points CP3is larger than a total number of the plurality of sprocket mounting portions14A. The total number of the plurality of additional circumferential coupling points CP3is larger than a total number of the plurality of sprocket mounting arms22. However, the total number of the plurality of additional circumferential coupling points CP3can be equal to or smaller than the total number of the plurality of sprocket mounting portions14A. The total number of the plurality of additional circumferential coupling points CP3can be equal to or smaller than the total number of the plurality of sprocket mounting arms22.

As seen inFIG. 6. the fourth sprocket SP4has at least one second circumferential coupling point CP4. Namely, the second sprocket wheel SP4has at least one second circumferential coupling point CP4. In this embodiment, the second sprocket wheel SP4includes a plurality of second circumferential coupling points CP4. The second circumferential coupling points CP4are spaced apart from each other in the circumferential direction D1. The second circumferential coupling points CP4are provided in the same radial position and are provided at a constant pitch in the circumferential direction D1. A total number of the second circumferential coupling points CP4is 6. However, the total number of the second circumferential coupling points CP4is not limited to this embodiment. The second sprocket wheel SP4includes a plurality of through-holes SP4D. The second circumferential coupling point CP4is defined at a center of the through-hole SP4D. As seen inFIG. 2, the additional fastening member38extends through the through-hole SP4D and the mounting hole20B.

As seen inFIG. 18, the second sprocket wheel SP4is coupled to the radially extending surface16(FIG. 16) of at least one of the plurality of sprocket mounting portions14A to14E at the at least one second circumferential coupling point CP4. In this embodiment, the second sprocket wheel SP4is coupled to the plurality of radially extending surfaces16B (FIG. 16) of the plurality of sprocket mounting portions14B at the plurality of second circumferential coupling points CP4. The second sprocket wheel SP4is coupled to the radially extending surfaces16B (FIG. 16) of the sprocket mounting portions14B at the plurality of second circumferential coupling points CP4with the plurality of additional fastening members38. In other words, the second sprocket wheel SP4is coupled to the second circumferential sprocket-mounting portion19B at the at least one second circumferential coupling point CP4. The second sprocket wheel SP4is coupled to the second circumferential sprocket-mounting portion19B at the at least one second circumferential coupling point CP4with the at least one second fastener38. The second sprocket wheel SP4is coupled to the second circumferential sprocket-mounting portion19B at the plurality of second circumferential coupling points CP4with the plurality of second fasteners38. The additional circumferential coupling point (the second circumferential coupling point) CP4can be defined by the second fastener38.

A total number of the at least one second circumferential coupling point CP4is equal to or larger than a total number of the at least one first circumferential coupling point CP1. In this embodiment, the total number of the at least one second circumferential coupling point CP4is equal to the total number of the at least one first circumferential coupling point CP1. However, the total number of the at least one second circumferential coupling point CP4can be smaller or larger than the total number of the at least one first circumferential coupling point CP1.

The second circumferential coupling point CP4is provided radially inwardly of the circumferential coupling point CP1, the additional circumferential coupling point CP2, and the additional circumferential coupling point CP3. The additional circumferential coupling point CP2and the additional circumferential coupling point CP3are radially outwardly of the circumferential coupling point CP1. The additional circumferential coupling point CP3is radially outwardly of the circumferential coupling point CP1and the additional circumferential coupling point CP2. The additional circumferential coupling point CP2and the additional circumferential coupling point CP3are offset from the circumferential coupling point CP1and the second circumferential coupling point CP4in the circumferential direction D1. The additional circumferential coupling point CP2is offset from the additional circumferential coupling point CP3in the circumferential direction D1. However, the arrangement of the circumferential coupling point CP1, the additional circumferential coupling point CP2, the additional circumferential coupling point CP3, and the second circumferential coupling point CP4is not limited to this embodiment.

As seen inFIG. 7, the sprocket SP5includes a plurality of through-holes SP5D. A total number of the through-holes SP5D is 6. However, the total number of the through-holes SP5D is not limited to this embodiment. As seen inFIG. 2, the additional fastening member40extends through the through-hole SP5D and the mounting hole20C.

As seen inFIG. 8, the sprocket SP6includes a plurality of through-holes SP6D. A total number of the through-holes SP6D is 6. However, the total number of the through-holes SP6D is not limited to this embodiment. As seen inFIG. 2, the additional fastening member42extends through the through-hole SP6D and the mounting hole20D.

As seen inFIG. 9, the sprocket SP7includes a plurality of through-holes SP7D. A total number of the through-holes SP7D is 6. However, the total number of the through-holes SP7D is not limited to this embodiment. As seen inFIG. 10, the sprocket SP8includes a plurality of through-holes SP8D. The through-holes SP8D are provided at positions corresponding to the through-holes SP7D. A total number of the through-holes SP8D is 6. However, the total number of the through-holes SP8D is not limited to this embodiment.

As seen inFIG. 2, the sprockets SP7and SP8are coupled to the sprocket mounting portion14E with the additional fastening member42. The bicycle rear sprocket assembly10comprises a plurality of spacers SC3provided between the sprockets SP7and SP8in the axial direction D2. The spacer SC3includes a spacer hole SC3A. The additional fastening member42extends through the through-hole SP7D, the through-hole SP8D, the mounting hole20E, and the spacer hole SC3A. The spacer SC3can be integrally formed with the additional fastening member44as a unitary, one-piece member.

As seen inFIG. 11, the sprocket SP9includes an internal spline SP9S. The internal spline SP9S includes a plurality of internal spline teeth SP9T configured to engage with the plurality of external spline teeth (not shown) of the bicycle rear hub assembly H (FIG. 2). As seen inFIG. 2, the sprocket SP9is held between the central portion21of the sprocket carrier12and the lock member H1of the bicycle rear hub assembly H in the axial direction D2in a state where the bicycle rear sprocket assembly10is mounted on the bicycle rear hub assembly H.

As seen inFIG. 12, the sprocket SP10includes an internal spline SP10S. The internal spline SP10S includes a plurality of internal spline teeth SP10T configured to engage with the plurality of external spline teeth (not shown) of the bicycle rear hub assembly H (FIG. 2). As seen inFIG. 2, the sprocket SP10is held between the central portion21of the sprocket carrier12and the lock member H1of the bicycle rear hub assembly H in the axial direction D2in a state where the bicycle rear sprocket assembly10is mounted on the bicycle rear hub assembly H.

As seen inFIG. 20, the sprocket SP11includes an internal spline SP11S. The internal spline SP11S includes a plurality of internal spline teeth SP11T configured to engage with the plurality of external spline teeth (not shown) of the bicycle rear hub assembly H (FIG. 2). As seen inFIG. 2, the sprocket SP11is held between the central portion21of the sprocket carrier12and the lock member H1of the bicycle rear hub assembly H in the axial direction D2in a state where the bicycle rear sprocket assembly10is mounted on the bicycle rear hub assembly H.

As seen inFIG. 21, the sprocket SP12includes a torque transmitting profile SP12F. The torque transmitting profile SP12F includes a plurality of external spline teeth SP12G configured to engage with the sprocket SP11to transmit a rotational force. As seen inFIG. 13, the sprocket SP11includes a torque transmitting profile SP11F. The torque transmitting profile SP11F includes a plurality of additional internal spline teeth SP11G configured to engage with the plurality of external spline teeth SP12G of the sprocket SP12to transmit the rotational force.

Second Embodiment

A bicycle rear sprocket assembly210in accordance with a second embodiment will be described below referring toFIGS. 22 to 24. The bicycle rear sprocket assembly210has the same structure and/or configuration as those of the bicycle rear sprocket assembly10except for the sprocket carrier12. Thus, elements having substantially the same function as those in the first embodiment will be numbered the same here, and will not be described and/or illustrated again in detail here for the sake of brevity.

As seen inFIG. 22, the bicycle rear sprocket assembly210comprises the plurality of sprockets SP and a sprocket carrier212. The second sprocket SP2is coupled, at the at least one additional circumferential coupling point CP2, to at least one of the sprocket carrier212and one of the plurality of sprockets SP1to SP12. In this embodiment, the second sprocket SP2is coupled to the sprocket carrier212at the at least one additional circumferential coupling point CP2. The second sprocket SP2is coupled to the sprocket carrier212at the plurality of additional circumferential coupling points CP2.

The bicycle rear sprocket assembly210further comprises the at least one fastening member34. The second sprocket SP2is coupled to the sprocket carrier212at the at least one additional circumferential coupling point CP2with the at least one fastening member34. In this embodiment, the bicycle rear sprocket assembly210further comprises the plurality of fastening members34. The at least one additional circumferential coupling point CP2includes the plurality of additional circumferential coupling points CP2. The second sprocket SP2is coupled to the sprocket carrier212at the plurality of additional circumferential coupling points CP2with the plurality of fastening members34.

As seen inFIG. 23, the sprocket carrier212has substantially the same structure as that of the sprocket carrier12of the first embodiment. In this embodiment, the sprocket carrier212includes a plurality of additional sprocket mounting portions250. A pair of the additional sprocket mounting portions250extend radially outwardly from the sprocket mounting arm22. In this embodiment, a total number of the additional sprocket mounting portions250is 12. However, the total number of the additional sprocket mounting portions250is not limited to this embodiment. For example, the pair of the additional sprocket mounting portions250can be one sprocket mounting portion or at least three sprocket mounting portions. The arrangement of the circumferential coupling point CP1, the additional circumferential coupling point CP2, the additional circumferential coupling point CP3, and the second circumferential coupling point CP4in the first embodiment can be applied to this embodiment.

As seen inFIG. 24, the additional sprocket mounting portion250is provided between the sprockets SP2and SP3in the axial direction D2. The additional through-holes SP1E are omitted from the first sprocket SP1. The spacers SC1and SC2are omitted from the bicycle rear sprocket assembly210. The additional sprocket mounting portion250includes a mounting through-hole250A and an additional mounting through-hole250B. The fastening member34extends through the through-holes SP2D and the mounting through-hole250A. The fastening member36extends through the additional through-hole SP2E, the through-holes SP3D, and the additional mounting through-hole250B.

Modifications

The structures of bicycle rear sprocket assemblies10and210can be combined with each other. As seen in a bicycle rear sprocket assembly310ofFIG. 25, for example, the second sprocket SP2is coupled, at the at least one additional circumferential coupling point CP2, to both the sprocket carrier212and one of the plurality of sprockets SP1to SP12. The second sprocket SP2is coupled, at the plurality of additional circumferential coupling points CP2, to both the sprocket carrier212and the first sprocket SP1with the plurality of fastening members34.

The terms “a” (or “an”), “one or more” and “at least one” can be used interchangeably herein.

Finally, terms of degree such as “substantially,” “about” and “approximately” as used herein mean a reasonable amount of deviation of the modified term such that the end result is not significantly changed. All of numerical values described in the present application can be construed as including the terms such as “substantially,” “about” and “approximately.”