Bicycle rear sprocket assembly

Patent metadata

Field	Value
Publication number	US-10457353-B2
Application number	US-201615288960-A
Country	US
Kind code	B2
Filing date	Oct 7, 2016
Priority date	Oct 7, 2016
Publication date	Oct 29, 2019
Grant date	Oct 29, 2019

Abstract

A bicycle rear sprocket assembly is basically provided that includes a first sprocket including a first sprocket body and a plurality of first sprocket teeth provided to an outer periphery thereof. Each of a plurality of first circumferential areas has a first circumferential length. A first total number of the plurality of first circumferential areas is an even number. A first circumferential area counting number from a driving surface of a first shifting initiation tooth to a driving surface of a second shifting initiation tooth in a driving rotational direction of the bicycle rear sprocket assembly is an odd number. A second circumferential area counting number from the driving surface of the second shifting initiation tooth to the driving surface of the first shifting initiation tooth in the driving rotational direction is an odd number. The first circumferential area counting number is different from the second circumferential area counting number.

First claim

What is claimed is:

1. A bicycle rear sprocket assembly comprising:
a first sprocket and a second sprocket, the second sprocket being adjacent to the first sprocket in an axial direction parallel to a rotational center axis of the bicycle rear sprocket assembly without another sprocket disposed between the first sprocket and the second sprocket, the first sprocket including
a first sprocket body;
a plurality of first sprocket teeth provided to an outer periphery of the first sprocket body, the plurality of first sprocket teeth including a first shifting initiation tooth and a second shifting initiation tooth, a plurality of first circumferential areas each of which has a first circumferential length corresponding to a single tooth pitch defined from a driving surface of a tooth of the first sprocket teeth to a driving surface of an adjacent tooth of the first sprocket teeth, the adjacent tooth being adjacent to the tooth without another tooth of the first sprocket teeth therebetween;
a first total number of the plurality of first circumferential areas is an even number;
a first shifting facilitation area in which the first shifting initiation tooth is disposed, the first shifting facilitation area including a first axially recessed portion to facilitate an upshifting operation;
a second shifting facilitation area in which the second shifting initiation tooth is disposed, the second shifting facilitation area including a second axially recessed portion to facilitate an upshifting operation;
a third shifting facilitation area configured to facilitate a shifting operation from the second sprocket to the first sprocket, the third shifting facilitation area including a third axially recessed portion to facilitate a downshifting operation, the third axially recessed portion being disposed between the second axially recessed portion and the first axially recessed portion in a driving rotational direction configured to move a bicycle in the forward direction; wherein the third axially recessed portion is adjacent to the first axially recessed portion;
a first circumferential area counting number from a driving surface of the first shifting initiation tooth to a driving surface of the second shifting initiation tooth in the driving rotational direction with respect to the rotational center axis of the bicycle rear sprocket assembly being an odd number; and
a second circumferential area counting number from the driving surface of the second shifting initiation tooth to the driving surface of the first shifting initiation tooth in the driving rotational direction being an odd number; and
the first circumferential area counting number being different from the second circumferential area counting number.

2. The bicycle rear sprocket assembly according to claim 1 , wherein
the second sprocket includes
a second sprocket body;
a plurality of second sprocket teeth provided to an outer periphery of the second sprocket body, a plurality of second circumferential areas each of which has a second circumferential length corresponding to a single tooth pitch defined from a driving surface of a tooth of the second sprocket teeth to a driving surface of an adjacent tooth of the second sprocket teeth, the adjacent tooth being adjacent to the tooth without another tooth of the second sprocket teeth therebetween; and
a second total number of the plurality of second circumferential areas being an even number and being smaller than the first total number of the plurality of first circumferential areas;

the first total number of the plurality of first circumferential areas minus the second total number of the plurality of second circumferential areas being equal to or larger than two; and
the first shifting facilitation area and the second shifting facilitation area being configured to facilitate a shifting operation from the first sprocket to the second sprocket.

3. The bicycle rear sprocket assembly according to claim 2 , wherein
the plurality of first sprocket teeth includes a neighboring tooth adjacent to the second shifting initiation tooth without another tooth between the second shifting initiation tooth and the neighboring tooth on the outer periphery of the first sprocket body in an upstream side of the driving rotational direction from the second shifting initiation tooth; and
the plurality of second sprocket teeth includes a chain-supporting tooth disposed between the second shifting initiation tooth and the neighboring tooth in a circumferential direction with respect to the rotational center axis when viewed from the axial direction.

4. The bicycle rear sprocket assembly according to claim 3 , wherein
the chain-supporting tooth has a tooth height that is larger than those of the plurality of the second sprocket teeth.

5. The bicycle rear sprocket assembly according to claim 3 , wherein
the chain supporting tooth has a recess on an axial facing surface facing the first sprocket.

6. The bicycle rear sprocket assembly according to claim 5 , wherein
a top surface of the recess is configured to contact a bicycle chain during an upshifting operation.

7. The bicycle rear sprocket assembly according to claim 2 , wherein
the first shifting facilitation area and the second shifting facilitation area being configured to facilitate a shifting operation from the first sprocket to the second sprocket.

8. The bicycle rear sprocket assembly according to claim 2 , wherein
the plurality of first sprocket teeth are configured to engage with a bicycle chain that includes a plurality of outer link plates and a plurality of inner link plates; and
the first shifting initiation tooth and the second shifting initiation tooth are configured to engage with a pair of outer link plates when the bicycle chain shifts from the first sprocket to the second sprocket, the outer link plates in each of the pairs of outer link plates face each other in the axial direction.

9. The bicycle rear sprocket assembly according to claim 8 , wherein
the bicycle chain is prevented from shifting from the first sprocket to the second sprocket when one of the first shifting initiation tooth and the second shifting initiation tooth engages with a pair of inner link plates, the inner link plates in each of the pairs of inner link plates face each other in the axial direction.

10. The bicycle rear sprocket assembly according to claim 1 , wherein
the third shifting facilitation area is partly overlapped with the first shifting facilitation area.

11. The bicycle rear sprocket assembly according to claim 1 , wherein
the third axially recessed portion is configured differently from the first axially recessed portion.

12. A bicycle rear sprocket assembly comprising:
a first sprocket and a second sprocket, the second sprocket being adjacent to the first sprocket in an axial direction parallel to a rotational center axis of the bicycle rear sprocket assembly without another sprocket disposed between the first sprocket and the second sprocket, the first sprocket including
a first sprocket body, a plurality of angular segments resulting from equally dividing the first sprocket body into even-numbered and equal to or more than ten angular segments;
a plurality of first sprocket teeth provided to an outer periphery of the first sprocket body, the plurality of first sprocket teeth including a first shifting initiation tooth and a second shifting initiation tooth, the first shifting initiation tooth being entirely disposed in a first angular segment among the plurality of angular segments and the second shifting initiation tooth being entirely disposed in a second angular segment among the plurality of angular segments;

Assignees

• Shimano Kk

Inventors

• Kamada Kenji
• Yamazaki Azusa

Classifications

• B62M9/10 Primary

  involving different-sized wheels, {e.g. rear sprocket chain wheels} selectively engaged by the chain, belt, or the like {(bicycle hubs rotatably arranged on axle B60B27/023)} · CPC title

• F16H55/30 Primary

  Chain-wheels · CPC title

• B62M9/12

  the chain, belt, or the like being laterally shiftable {, e.g. using a rear derailleur} · CPC title