BICYCLE REAR SPROCKET

• US 20150285358A1
• Filed: 04/02/2014
• Published: 10/08/2015
• Est. Priority Date: 04/02/2014
• Status: Active Grant

• Current Assignee: Shimano Inc
• Original Assignee: Shimano Inc
• Inventors: FUKUMORI, Tsuyoshi, NUMATA, Shingo
• Granted Patent: US 9,297,450 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B62M 9/10 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 Class Codes: F16H 55/08 Profiling
• CPC Class Codes: F16H 55/0873 for improving axial engagement, e.g. a chamfer at the end of the tooth flank

Abstract

A bicycle rear sprocket is basically provided with a sprocket body and a chain engagement structure. The sprocket body has a center rotational axis, a first side surface and a second side surface. The first and second side surfaces face oppositely with respect to an axial direction of the bicycle rear sprocket. The first side surface is a smaller sprocket facing side of the sprocket body. The chain engagement structure includes a plurality of sprocket teeth extending radially outward from an outer periphery of the sprocket body. The sprocket teeth include a first shift tooth and a second shift tooth. The second shift tooth is positioned at a third tooth position in a downstream direction of a rotational driving direction of the bicycle rear sprocket with respect to the first shift tooth. The first shift tooth and the second shift tooth function as a shift tooth when a bicycle chain moves from a smaller bicycle rear sprocket to the bicycle rear sprocket.

Claims

1. A bicycle rear sprocket comprising:

a sprocket body having a center rotational axis, a first side surface and a second side surface, the first and second side surfaces facing oppositely with respect to an axial direction of the bicycle rear sprocket, the first side surface being a smaller sprocket facing side of the sprocket body; and

a chain engagement structure including a plurality of sprocket teeth extending radially outward from an outer periphery of the sprocket body,

the sprocket teeth including a first shift tooth and a second shift tooth, the second shift tooth being positioned at a third tooth position in a downstream direction of a rotational driving direction of the bicycle rear sprocket with respect to the first shift tooth, the first shift tooth and the second shift tooth functioning as a shift tooth when a bicycle chain moves from a smaller bicycle rear sprocket to the bicycle rear sprocket.

2. The bicycle rear sprocket according to claim 1, wherein

the sprocket teeth include either a first non-shift tooth with a first recess on the first side surface of the sprocket body, or a first toothless gap that is positioned in the downstream direction with respect to the first shift tooth.

3. The bicycle rear sprocket according to claim 2, wherein

the sprocket teeth include either a second non-shift tooth with a second recess on the first side surface of the sprocket body, or a second toothless gap that is positioned in the downstream direction with respect to the second shift tooth.

4. The bicycle rear sprocket according to claim 1, wherein

the first shift tooth has a first tip having a first leading corner on the first side surface of the sprocket body and a first trailing corner on the first side surface of the sprocket body, the first leading corner being positioned in the downstream direction with respect to the first trailing corner, the first leading corner being positioned closer to the first side surface of the sprocket body than the first trailing corner in the axial direction with respect to the center rotational axis.

5. The bicycle rear sprocket according to claim 4, wherein

the second shift tooth has a second tip having a second leading corner on the first side surface of the sprocket body and a second trailing corner on the second side surface of the sprocket body, the second leading corner being positioned in the downstream direction with respect to the second trailing corner, the second leading corner being positioned closer to the first side surface of the sprocket body than the second trailing corner in the axial direction.

6. The bicycle rear sprocket according to claim 1, wherein

a to a number of the sprocket teeth is equal to or more than fifteen.

7. A bicycle rear sprocket assembly comprising:

a first rear sprocket including

a first sprocket body having a center rotational axis, and

a first chain engagement structure including a plurality of first sprocket teeth extending radially outward from an outer periphery of the first sprocket body,

the first sprocket teeth including a first shift tooth and a second shift tooth, the second shift tooth being positioned at a third tooth position in a downstream direction of a rotational driving direction of the bicycle rear sprocket with respect to the first shift tooth; and

a second rear sprocket

a second sprocket body having the center rotational axis, and

a second chain engagement structure including a plurality of second sprocket teeth extending radially outward from an outer periphery of the second sprocket body, the second sprocket being positioned adjacent to the first sprocket in an axial direction with respect to the center rotational axis;

a total number of the first sprocket teeth being larger than a total number of the second sprocket teeth by one, each of the first shift toot and the second shift tooth selectively functioning as a shift tooth when a bicycle chain moves from the second rear sprocket to the first rear sprocket.

8. The bicycle rear sprocket assembly according to claim 7, wherein

the first sprocket body has a first side surface and a second side surface, the first and second side surfaces facing oppositely with respect to an axial direction of the bicycle rear sprocket assembly, and the first side surface facing the second sprocket.

9. The bicycle rear sprocket assembly according to claim 8, wherein

the first sprocket teeth include either a first non-shift tooth with a first recess on the first side surface of the first sprocket body, or a first toothless gap that is positioned in the downstream direction with respect to the first shift tooth.

10. The bicycle rear sprocket assembly according to claim 9, wherein

the first sprocket teeth include either a second non-shift tooth with a second recess on the first side surface of the first sprocket body, or a second toothless gap that is positioned in the downstream direction with respect to the second shift tooth.

11. The bicycle rear sprocket assembly according to claim 7, wherein

the first shift tooth has a first tip having a first leading corner on the first side surface of the first sprocket body and a first trailing corner on the first side surface of the first sprocket body, the first leading corner being positioned in the downstream direction with respect to the first trailing corner, the first leading corner being positioned closer to the first side surface of the first sprocket body than the first trailing corner in the axial direction with respect to the center rotational axis.

12. The bicycle rear sprocket assembly according to claim 11, wherein

the second shift tooth has a second tip having a second leading corner on the first side surface of the first sprocket body and a second trailing corner on the second side surface of the first sprocket body, the second leading corner being positioned in the downstream direction with respect to the second trailing corner, the second leading corner being positioned closer to the first side surface of the first sprocket body than the second trailing corner in the axial direction.

13. The bicycle rear sprocket assembly according to claim 7, wherein

a total number of the first sprocket teeth is equal to or more than fifteen.