BICYCLE SPROCKET

Abstract

Bicycle sprocket (14, 114, 214, 314), comprising: a gear ring body (18) having a central axis of rotation (X); and a plurality of chain drive teeth (20, 220) extending radially outward from the sprocket body (18) to engage a bicycle chain (22), the plurality of chain drive teeth (20, 220) comprising a first axial surface (20a, 220a), a second axial surface (20b, 220b) opposite the first axial surface (20a, 220a) with respect to an axial direction of the central axis of rotation (X), at least one recess (38, 238, 338) provided on at least one of the first and second axial surfaces (20a, 20b, 220a, 220b) for storing a lubricant on the at least one of the first and second axial surfaces (20a, 20b, 220a, 220b), wherein the plurality of chain drive teeth (20, 220) comprises: at least one first tooth (34, 134, 234, 334) having a first maximum axial width (W1) defined in the axial direction; and at least one second tooth (36, 136, 236, 336) having a second maximum axial width (W2) defined in the axial direction, wherein the second maximum axial width (W2) is smaller than the first maximum axial width (W1).

Description

[0001] This invention generally relates to a bicycle sprocket. More specifically, the present invention relates to a bicycle sprocket having a plurality of chain drive teeth configured to reduce wear of the chain drive teeth.

[0002] Most bicycles have a drive unit or drivetrain that uses a bicycle chain to transmit pedaling action from the rider to the rear wheel. A bicycle drivetrain typically includes at least one front sprocket provided on a bicycle crank assembly of the bicycle and at least one rear sprocket provided on a rear hub of the bicycle. The bicycle chain is wound around the front and rear sprockets. Thus, rotation of the bicycle crank assembly by the rider is transmitted to the rear wheel via the bicycle chain, which engages the front and rear sprockets. Some bicycles are provided with a plurality of front sprockets or a single front sprocket. The front sprockets are often attached to a crank arm to form a bicycle front sprocket assembly.

[0003] DE 10 2018 202 911 A1 discloses a bicycle sprocket comprising a sprocket body and a plurality of chain drive teeth. The sprocket body has a central rotational axis. The plurality of chain drive teeth extend radially outward from the sprocket body to engage a bicycle chain. The plurality of chain drive teeth has a first axial surface and a second axial surface opposite the first axial surface with respect to an axial direction of the central rotational axis. The chain drive teeth include a laminated layer structure with a carbon-plated layer having porous properties and a lubricant impregnated into the carbon-plated layer. Summary of the invention

[0004] Generally, the present invention is directed to various features of a bicycle sprocket. One feature provides a bicycle sprocket having a plurality of chain drive teeth that include at least one recess on an axial surface.

[0005] The object of the invention is to reduce the wear of the chain drive teeth in a bicycle sprocket.

[0006] According to a first aspect of the present invention, a bicycle sprocket is provided, which essentially comprises a sprocket body and a plurality of chain drive teeth. The sprocket body has a central rotational axis. The plurality of chain drive teeth extend radially outward from the sprocket body to engage a bicycle chain. The plurality of chain drive teeth have a first axial surface and a second axial surface opposite to the first axial surface with respect to an axial direction of the central rotational axis. The plurality of chain drive teeth further have at least one recess provided on at least one of the first and second axial surfaces for storing a lubricant on the at least one of the first and second axial surfaces. The plurality of chain drive teeth comprises at least one first tooth and at least one second tooth.The at least one first tooth has a first maximum axial width defined in the axial direction. The at least one second tooth has a second maximum axial width defined in the axial direction. The second maximum axial width is smaller than the first maximum axial width.

[0007] Advantageously, according to the first aspect, the bicycle sprocket is designed to reduce the amount of wear on the chain drive teeth resulting from the sliding of the bicycle chain. Advantageously, the bicycle sprocket is designed to have at least one first tooth and at least one second tooth arranged as wide and narrow teeth to prevent the chain from falling off.

[0008] According to a second aspect of the present invention, the bicycle sprocket according to the first aspect is configured such that the first maximum axial width is larger than an inner link gap. The inner link gap is defined between an opposing pair of inner link plates of the bicycle chain in the axial direction. The first maximum axial width is smaller than an outer link gap. The outer link gap is defined between an opposing pair of outer link plates of the bicycle chain in the axial direction. The second maximum axial width is smaller than the inner link gap. Advantageously, according to the second aspect, the bicycle sprocket is configured to have at least one first tooth and at least one second tooth arranged as wide and narrow teeth to prevent the chain from falling off.

[0009] According to a third aspect of the present invention, the bicycle sprocket according to one of the first and second aspects is configured such that the first maximum axial width is greater than or equal to 2.5 millimeters and less than or equal to 5.4 millimeters. Advantageously, according to the third aspect, the bicycle sprocket is configured to have at least one first tooth and at least one second tooth arranged as wide and narrow teeth to prevent the chain from falling off.

[0010] According to a fourth aspect of the present invention, the bicycle sprocket according to the third aspect is configured such that the first maximum axial width is greater than or equal to 3 millimeters and less than or equal to 4.5 millimeters. Advantageously, according to the fourth aspect, the bicycle sprocket is configured to have at least one first tooth and at least one second tooth, which are arranged as wide and narrow teeth, respectively, to prevent the chain from falling off.

[0011] According to a fifth aspect of the present invention, the bicycle sprocket according to any one of the first to fourth aspects is configured such that the first maximum axial width of the at least one first tooth has a first axial percentage of the outer link gap of the outer link plates in the axial direction. The first axial percentage is greater than or equal to 75 percent and less than or equal to 93 percent. Advantageously, according to the fifth aspect, the bicycle sprocket is configured to have at least one first tooth and at least one second tooth arranged as wide and narrow teeth to prevent chain drop.

[0012] According to a sixth aspect of the present invention, the bicycle sprocket according to any one of the first to fifth aspects is configured such that the second maximum axial width of the at least one second tooth comprises a second axial percentage of the inner link gap of the inner link plates in the axial direction. The second axial percentage is greater than or equal to 75 percent and less than or equal to 93 percent. Advantageously, according to the sixth aspect, the bicycle sprocket is configured to have at least one first tooth and at least one second tooth arranged as wide and narrow teeth to prevent chain drop.

[0013] According to a seventh aspect of the present invention, the bicycle sprocket according to any one of the first to sixth aspects is configured such that the at least one recess is provided on at least one of the first axial surface and the second axial surface of the at least one first tooth. Advantageously, according to the seventh aspect, the bicycle sprocket is configured to have a recess provided on the first axial surface of the at least one tooth that engages the bicycle chain during operation to wear the first tooth in the axial direction.

[0014] According to an eighth aspect of the present invention, the bicycle sprocket according to any one of the first to seventh aspects is configured such that, in a state in which the bicycle sprocket is mounted on a bicycle frame, the first axial surface is configured to be located closer to the bicycle frame in the axial direction than the second axial surface. The at least one recess is provided on the second axial surface of the at least one first tooth. Advantageously, according to the eighth aspect, the bicycle sprocket is configured to reduce wear on the first tooth when the bicycle sprocket is inclined outward with respect to the rear sprocket.

[0015] According to a ninth aspect of the present invention, the bicycle sprocket according to the eighth aspect is configured such that the first axial surface of the at least one first tooth is free of the at least one recess. Advantageously, according to the ninth aspect, the bicycle sprocket is configured to reduce wear on the first tooth without the need to provide the recess on the first axial surface.

[0016] According to a tenth aspect of the present invention, the bicycle sprocket according to the eighth aspect is configured such that the at least one recess is provided on both the first axial surface and the second axial surface of the at least one first tooth. Advantageously, according to the tenth aspect, the bicycle sprocket is configured to reduce wear on the first tooth on the first and second axial surfaces of the first tooth.

[0017] According to an eleventh aspect of the present invention, the bicycle sprocket according to any one of the first to tenth aspects is configured such that the at least one recess is provided on at least one of the first axial surface and the second axial surface of the at least one second tooth. Advantageously, according to the eleventh aspect, the bicycle sprocket is configured to reduce wear on the first and second axial surfaces of the second tooth.

[0018] According to a twelfth aspect of the present invention, the bicycle sprocket according to any one of the first to eleventh aspects is configured such that the plurality of chain drive teeth has a maximum axial width at a portion of the at least one first axial surface and the second axial surface. The at least one recess is provided at the portion of the at least one first axial surface and the second axial surface. Advantageously, according to the twelfth aspect, the bicycle sprocket is configured to reduce wear on the chain drive teeth.

[0019] According to a thirteenth aspect of the present invention, the bicycle sprocket according to any one of the first to twelfth aspects is configured such that a maximum depth of the at least one recess defined by at least one of the first axial surface and the second axial surface is less than or equal to 0.5 millimeters. Advantageously, according to the thirteenth aspect, the bicycle sprocket is configured to reduce wear on the chain drive teeth.

[0020] According to a fourteenth aspect of the present invention, the bicycle sprocket according to the thirteenth aspect is designed such that the maximum depth of the at least one recess is greater than or equal to 0.01 millimeters. Advantageously, according to the fourteenth aspect, the bicycle sprocket is designed to reduce wear on the chain drive teeth.

[0021] According to a fifteenth aspect of the present invention, a bicycle sprocket is provided, which essentially comprises a sprocket body and a plurality of chain drive teeth. The sprocket body has a central rotational axis. The plurality of chain drive teeth extend radially outward from the sprocket body to engage with a bicycle chain. The plurality of chain drive teeth have a first axial surface and a second axial surface opposite to the first axial surface with respect to an axial direction of the central rotational axis. The plurality of chain drive teeth further has at least one recess provided on at least one of the first and second axial surfaces for storing a lubricant on the at least one of the first and second axial surfaces.Furthermore, a maximum depth of the at least one recess defined by at least one of the first axial surface and the second axial surface is less than or equal to 0.5 millimeters. Furthermore, the maximum depth of the at least one recess is greater than or equal to 0.01 millimeters.

[0022] According to a sixteenth aspect of the present invention, the bicycle sprocket according to any one of the first to fifteenth aspects is configured such that a maximum width of the at least one recess defined along at least one of the first axial surface and the second axial surface is less than or equal to 2 millimeters. Advantageously, according to the sixteenth aspect, the bicycle sprocket is configured to reduce wear on the chain drive teeth.

[0023] According to a seventeenth aspect of the present invention, the bicycle sprocket according to the sixteenth aspect is designed such that the maximum width of the at least one recess is greater than or equal to 0.01 millimeters. Advantageously, according to the seventeenth aspect, the bicycle sprocket is designed to reduce wear on the chain drive teeth.

[0024] According to an eighteenth aspect of the present invention, the bicycle sprocket according to any one of the first to seventeenth aspects is configured such that the plurality of chain drive teeth comprises a base material and a wear-resistant layer covering the base material. The at least one recess is provided on the wear-resistant layer. Advantageously, according to the eighteenth aspect, the bicycle sprocket is configured to reduce wear on the chain drive teeth.

[0025] According to a nineteenth aspect of the present invention, the bicycle sprocket according to the eighteenth aspect is configured such that the base material comprises an aluminum alloy. Advantageously, according to the nineteenth aspect, the bicycle sprocket is configured to reduce wear on the chain drive teeth.

[0026] According to a twentieth aspect of the present invention, the bicycle sprocket according to any one of the eighteenth and nineteenth aspects is configured such that the wear-resistant layer comprises a ceramic material. Advantageously, according to the twentieth aspect, the bicycle sprocket is configured to reduce wear on the chain drive teeth.

[0027] According to a twenty-first aspect of the present invention, the bicycle sprocket according to any one of the first to twentieth aspects is configured such that the at least one recess has an elongated profile defined by an outer edge of the at least one recess. The at least one recess extends in a circumferential direction around the central rotational axis. Advantageously, according to the twenty-first aspect, the bicycle sprocket is configured to reduce wear on the chain drive teeth.

[0028] According to a twenty-second aspect of the present invention, a bicycle sprocket is provided, which essentially comprises a sprocket body and a plurality of chain drive teeth. The sprocket body has a central rotational axis. The plurality of chain drive teeth extend radially outward from the sprocket body to engage a bicycle chain. The plurality of chain drive teeth have a first axial surface and a second axial surface opposite the first axial surface with respect to an axial direction of the central rotational axis. The plurality of chain drive teeth further includes at least one recess provided on at least one of the first and second axial surfaces for storing a lubricant on the at least one of the first and second axial surfaces. Furthermore, the at least one recess has an elongated profile defined by an outer edge of the at least one recess.The at least one recess extends in a circumferential direction around the central axis of rotation.

[0029] According to a twenty-third aspect of the present invention, the bicycle sprocket according to the twenty-first and twenty-second aspects is configured such that the outer edge of the at least one recess is located entirely within an outer edge of at least one of the first axial surface and the second axial surface of the plurality of chain drive teeth. Advantageously, according to the twenty-third aspect, the bicycle sprocket is configured to reduce wear on the chain drive teeth.

[0030] According to a twenty-fourth aspect of the present invention, the bicycle sprocket according to any one of the twenty-first to twenty-third aspects is configured such that the profile of the at least one recess has a non-circular and non-polygonal shape. Advantageously, according to the twenty-fourth aspect, the bicycle sprocket is configured to reduce wear on the chain drive teeth.

[0031] According to a twenty-fifth aspect of the present invention, the bicycle sprocket according to any one of the twenty-first to twenty-fourth aspects is configured such that the profile of the at least one recess has a curved shape. Advantageously, according to the twenty-fifth aspect, the bicycle sprocket is configured to reduce wear on the chain drive teeth.

[0032] According to a twenty-sixth aspect of the present invention, the bicycle sprocket according to any one of the first to twenty-fifth aspects is configured such that the plurality of chain drive teeth comprises at least thirty chain drive teeth. Advantageously, according to the twenty-sixth aspect, the bicycle sprocket is configured to reduce wear on the chain drive teeth for a mountain bike.

[0033] According to a twenty-seventh aspect of the present invention, the bicycle sprocket according to any one of the first to twenty-fourth aspects is configured such that the at least one recess consists of only a single recess provided on at least one of the first and second axial surfaces of the plurality of chain drive teeth. Advantageously, according to the twenty-seventh aspect, the bicycle sprocket is configured to reduce wear on the chain drive teeth.

[0034] According to a twenty-eighth aspect of the present invention, the bicycle sprocket according to any one of the first to twenty-seventh aspects is configured such that a lubricant is provided at the at least one recess. Advantageously, according to the twenty-eighth aspect, the bicycle sprocket is configured to reduce wear on the chain drive teeth.

[0035] Other objects, features and advantages of the disclosed bicycle sprocket will also become apparent to those skilled in the bicycle art from the following detailed description, which, together with the accompanying drawings, discloses illustrative embodiments of the bicycle sprocket. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Reference is now made to the accompanying drawings which form a part of this original disclosure: Fig. 1 is a simplified plan view of a bicycle drivetrain including a bicycle crank assembly and a rear cassette having a plurality of rear sprockets mounted on a rear hub according to a first illustrated embodiment; Fig. 2 is an enlarged exterior view of a section of the Fig. 1 shown bicycle crank assembly; Fig. 3 is an enlarged perspective view of a portion of a (front) bicycle sprocket shown in the Fig. 1 and Fig. 2, which engages a bicycle chain; Fig. 4 is the enlarged perspective view of the section of the Fig. 3 illustrated bicycle sprocket, with the bicycle chain removed; Fig. Figure 5 is an edge view of a portion of the chain drive teeth of the bicycle sprocket shown in the Fig. 2 to 4; Fig. 6 is an enlarged side view of a first axial surface of a first tooth and a second tooth of the bicycle sprocket shown in the Fig. 3 to 5, which have recesses according to the first embodiment shown; Fig. 7 is an enlarged side view of a second axial surface of the first tooth and the second tooth shown in Fig. 6, which have recesses according to the first embodiment shown; Fig. 8 is an enlarged side view of a first axial surface of a first tooth and a second tooth of a first modified bicycle sprocket having first modified recesses. Fig. 9 is an enlarged side view of a second axial surface of the first tooth and the second tooth of the first modified bicycle sprocket shown in Fig. 8, which have the first modified depressions; Fig. 10 is an enlarged side view of a first axial surface of a first tooth and a second tooth of a second modified bicycle sprocket having second modified recesses; Fig. 11 is an enlarged side view of a second axial surface of a first tooth and a second tooth of the second modified bicycle sprocket shown in Fig. 10 having the second modified recesses; Fig. 12 is an enlarged side view of a first axial surface of a first tooth and a second tooth of a third modified bicycle sprocket having third modified recesses; and Fig. 13 is an enlarged side view of a second axial surface of a first tooth and a second tooth of the third modified bicycle sprocket of Fig. 12, which have the third modified recesses. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0037] Selected embodiments will now be explained with reference to the drawings. It will be apparent to those skilled in the bicycle art from this disclosure that the following descriptions of the embodiments are provided for illustrative purposes.

[0038] If one initially refers to Fig. 1, a bicycle drivetrain 1 is shown including a bicycle crank assembly 10 and a rear cassette 12 according to a first embodiment. In the first embodiment, the bicycle crank assembly 10 includes a bicycle sprocket 14 and a crank arm 16. In the illustrated embodiment, the bicycle sprocket 14 is a front sprocket. The bicycle crank assembly 10 is an example of a bicycle crank assembly having a single sprocket or chainring. The bicycle sprocket 14 includes a sprocket body 18 and a plurality of chain drive teeth 20 for engaging a bicycle chain 22, as discussed further below.

[0039] The rear cassette 12 is attached to a rear hub 24. The bicycle sprocket 14 and the rear cassette 12 are configured to engage the bicycle chain 22. The rear cassette 12 and the rear hub 24 are conventional and will not be discussed further here.

[0040] While Fig. 1 illustrates the bicycle crank assembly 10 already provided with the bicycle sprocket 14, it will be apparent to those skilled in the bicycle art from this disclosure that the bicycle sprocket 14 may be provided separately from the crank arm 16 of the bicycle crank assembly 10. That is, the bicycle sprocket 14 may be sold separately from the bicycle crank assembly 10.

[0041] How best in Fig. 2, the bicycle sprocket 14 has a plurality (e.g., four) fixing portions 26 for fixing the bicycle sprocket 14 to the crank arm 16. Specifically, each of the fixing portions 26 is fixed to a sprocket fixing arm 28 of the crank arm 16. In the first illustrated embodiment, each of the fixing portions 26 includes a through hole 26a. The bicycle sprocket 14 is fixed to the sprocket fixing arms 28 by a plurality of fixing fasteners B. For example, each of the fixing fasteners B includes a fixing screw and a nut (not shown) threaded to the fixing screw in a conventional manner.

[0042] The crank arm 16 is integrally and rotationally fixed to one end of a crankshaft 30. As in Fig. 2, the crankshaft 30 defines a rotational center axis X of the sprocket body 18. The sprocket body 18 has the rotational center axis X. As previously stated, the crank arm 16 includes four of the sprocket mounting arms 28 for attaching the bicycle sprocket 14 to the crank arm 16 in a conventional manner. The crank arm 16 further includes a pedal mounting portion 16a that receives a bicycle pedal (not shown) at one end of the crank arm 16. The crank arm 16 is an example of a first crank arm 16. As shown in Fig. 1, a second crank arm 32 is rotationally fixed to an opposite end of the crankshaft 30 relative to the first crank arm 16. The first and second crank arms 16 and 32 are conventional and will not be discussed further here.

[0043] As previously stated, the sprocket body 18 of the first illustrated embodiment includes the chain drive teeth 20. The chain drive teeth 20 are arranged along a circumferential direction of the sprocket body 18 relative to the central rotational axis X and extend radially outward from the sprocket body 18. Here, in the illustrated embodiment, the bicycle sprocket 14 includes, for example, thirty of the chain drive teeth 20. In the illustrated embodiment, the plurality of chain drive teeth 20 preferably includes at least thirty of the chain drive teeth 20.

[0044] As in the Fig. 2 to 4, the chain drive teeth 20 include a plurality of first teeth 34 and a plurality of second teeth 36. The first and second teeth 34 and 36 are formed as wide and narrow teeth, respectively. The first and second teeth 34 and 36 are arranged alternatively along an outer edge of the sprocket body 18.

[0045] How best to Fig. 1, Fig. 3 and Fig. 4, the plurality of chain drive teeth 20 further includes a first axial surface 20a and a second axial surface 20b opposite the first axial surface 20a with respect to an axial direction of the central rotational axis X. Accordingly, each of the first and second teeth 34 and 36 includes a portion of the first axial surface 20a and a portion of the second axial surface 20b. As best shown in Fig. 1, the first axial surface 20a is configured to be located closer to a bicycle frame (not shown) in the axial direction than the second axial surface 20b in a state in which the bicycle sprocket 14 is mounted to the bicycle frame. As will be explained further below, at least one recess 38 is provided on the chain drive teeth 20. In this disclosure, the at least one recess 38 is hereinafter referred to as "the recess 38." Specifically, the recess 38 is provided on at least one of the first and second axial surfaces 20a and 20b of the chain drive teeth 20, as will be discussed further below.

[0046] It will be apparent to those skilled in the bicycle art from this disclosure that all references to "the recess 38" may refer to a single recess or a plurality of recesses. Further, in the examples below, the chain drive teeth 20 are illustrated as having varying numbers of recesses 38. It will be apparent to those skilled in the bicycle art from this disclosure that in each of the examples, the total number of recesses 38 shown on the chain drive teeth 20 is illustrated for illustrative purposes only. It will be apparent to those skilled in the bicycle art from this disclosure that the chain drive teeth 20 may include multiple numbers of recesses 38, and that each of the chain drive teeth 20 may include the same or different numbers of recesses 38.For example, the chain drive teeth 20 may be provided with a single recess 38. Thus, the at least one recess 38 may consist of only a single recess 38 provided on at least one of the first and second axial surfaces 20a and 20b of the plurality of chain drive teeth 20.

[0047] When a bicycle rides over rough terrain, there is a possibility that the bicycle chain 22 may experience chain jump. That is, the bicycle chain 22 may jump and land back on the chain drive teeth 20 of the bicycle sprocket 14. As a result of the impact between the bicycle chain 22 and the chain drive teeth 20 when the bicycle chain 22 lands back on the chain drive teeth 20, the chain drive teeth 20 experience wear over time. Furthermore, when the bicycle chain 20 is driven, the first and second axial surfaces 20a and 20b may contact and rub against the inner surfaces of the inner link plates 22a and the outer link plates 22b. In particular, wear may occur on the first and second axial surfaces 20a and 20b of the chain drive teeth 20 where the bicycle chain 22 comes into contact therewith.Over time, the chain drive teeth 20 may become thin, and gaps between the first and second axial surfaces 20a and 20b and the inner surfaces of the inner and outer link plates 22a and 22b may increase. This increase may lead to a deterioration in chain retention performance. Thus, the chain drive teeth 20 of the bicycle sprocket 14 of the illustrated embodiment are provided with the recesses 38, as shown in FIGS. Fig. 6 and Fig. 7. The recesses 38 are designed to store lubricant to prevent wear of the chain drive teeth 20.

[0048] Thus, the bicycle sprocket 14 further includes a lubricant provided at the recess 38. As previously stated, the recess 38 is provided to store the lubricant that will help reduce wear on the chain drive teeth 20. Thus, the recess 38 is provided to store a lubricant on at least one of the first and second axial surfaces 20a and 20b. It will be apparent to those skilled in the bicycle art from this disclosure that the recesses 38 may be provided to store lubricant on both of the first and second axial surfaces 20a and 20b of the chain drive teeth 20. Thus, as shown in the Fig. 6 and Fig. As shown in Figure 7, the recesses 38 are provided on both the first axial surface 20a and the second axial surface 20b. The chain drive teeth 20 and the recesses 38 are discussed further below.

[0049] Now referring to the Fig. 2 and Fig. 3, the bicycle chain 22 will now be discussed. The bicycle chain 22 includes a plurality of parallel inner link plates 22a forming inner links and a plurality of parallel outer link plates 22b forming outer links, which are alternately connected to each other by a plurality of pins 23. Preferably, each of the pins 23 has a roller 25 rotatably mounted thereon. Typically, the inner link plates 22a are separated by an inner link space S1. The outer link plates 22b are separated by an outer link space S2.

[0050] Thus, how best in Fig. As shown in Figure 3, the inner link gap S1 is defined between an opposing pair of inner link plates 22a of the bicycle chain 22 in the axial direction. The outer link gap S2 is defined between an opposing pair of outer link plates 22b of the bicycle chain 22 in the axial direction. As shown, the outer link gap S2 is larger than the inner link gap S1. Thus, the bicycle chain 22 is a conventional bicycle chain and will not be discussed further here.

[0051] Now referring to Fig. 2, the bicycle sprocket 14 will now be discussed. As stated, the bicycle sprocket 14 includes the sprocket body 18 and the chain drive teeth 20. The sprocket body 18 and the chain drive teeth 20 may both be made of a metallic material and integrally formed as a one-piece, unitary element. If weight savings are needed and / or desired, the sprocket body 18 may comprise a non-metallic material, such as, preferably, a fiber-reinforced resin material, while the chain drive teeth 20 may comprise a metallic material.

[0052] An outer boundary of the sprocket body 18 is defined by a root circle R having a root radius Rc. As is well known, the root circle R is a hypothetical circle defined by the base (radially innermost point) of the low points or roots between the chain drive teeth 20. Thus, the root portion of the first and second teeth 34 and 36 refers to the portion of the first and second teeth 34 and 36 located at the root circle R extending circumferentially on the sprocket body 18 with respect to the central rotational axis X.

[0053] The chain drive teeth 20 are now shown with reference to the Fig. 6 and Fig. 7. As discussed in the Fig. 6 and Fig. 7, the plurality of chain drive teeth 20 comprises a base material 40 and a wear-resistant layer 42 covering the base material 40. That is, each of the chain drive teeth 20 comprises the base material 40 and the wear-resistant layer 42. In the embodiment shown, the wear-resistant layer 42 may completely cover or coat the base material 40, including the first and second axial surfaces 20a and 20b, as well as the circumferential and radial surfaces of the chain drive teeth 20. However, it will be apparent to those skilled in the bicycle art from this disclosure that the wear-resistant layer 42 may only cover the first and second axial surfaces 20a and 20b, as shown in FIGS. Fig. 6 and Fig. 7. For the purpose of clarity, the wear-resistant layer 42 is shown disposed only on the first and second axial surfaces 20a and 20b of the chain drive teeth 20.

[0054] Preferably, the base material 40 is made of a metallic material comprising an aluminum alloy. For example, the base material 40 may be an alloy comprising aluminum, titanium, stainless steel, magnesium, beryllium, or other suitable metallic materials. The base material 40 may also include portions made of a resin material, such as a fiber-reinforced resin material. The sprocket body 18 and the chain drive teeth 20 may both be made of a metallic material and may be integrally formed as a one-piece, unitary member. If weight savings are needed and / or desired, the sprocket body 18 may comprise a non-metallic material, such as preferably a fiber-reinforced resin material, while the base material 40 may comprise a metallic material.

[0055] In the embodiment shown, the wear-resistant layer 42 comprises a ceramic material that is hard, tough, and corrosion-resistant. For example, the wear-resistant layer 42 may comprise chromium nitride (CrN), aluminum oxide (Al2O3), or titanium nitride (TiN). Alternatively, instead of a layer of the ceramic material, the wear-resistant layer 42 may also be a plating layer, such as a nickel plating layer. It will be apparent to those skilled in the bicycle art that the wear-resistant layer 42 may also be made of any other suitable material that can be used as a coating on metallic and metallic alloy components to improve the surface properties of the substrate. In the embodiment shown, the wear-resistant layer 42 preferably has a thickness of 1.1 to 1.7 micrometers. Preferably, as shown, the recess 38 is provided on the wear-resistant layer 42.

[0056] As stated, the chain drive teeth 20 include a plurality of first and second teeth 34 and 36. The first teeth 34 and the second teeth 36 are arranged alternately in a circumferential direction along the bicycle sprocket 14. While the first and second teeth 34 and 36 are illustrated as straight, symmetrical teeth, it will be appreciated from this disclosure that the first and second teeth 34 and 36 may be asymmetrical teeth, twisted teeth, shifting teeth with shifting features, and / or the like. Since all of the first teeth 34 are identical and all of the second teeth 36 are identical, the following description regarding the first and second teeth 34 and 36 will refer to a single first tooth 34 and a single second tooth 36, respectively. Thus, the chain drive teeth 20 include at least one first tooth 34 and at least one second tooth 36.

[0057] Referring to the Fig. 6 and Fig. 7, the first tooth 34 has a first edge 34a disposed adjacent a first circumferential surface, a second edge 34b disposed adjacent a second circumferential surface, and a first tip portion 34c disposed circumferentially between the first and second edges 34a and 34b. The first edge 34a, the second edge 34b, and an edge of the first tip portion 34c define an outer periphery 34d of the first tooth 34. In the embodiment shown, as best shown in FIGS. Fig. 4 and Fig. 5, the first tooth 34 includes an axially projecting portion 34e on the first and second axial surfaces 20a and 20b of the first tooth 34. The axially projecting portion 34e defines a first maximum axial width W1 of the first tooth 34, as will be discussed further below. The first tooth 34 further includes a first curved portion 34f, which is an arcuate surface formed on the first and second axial surfaces 20a and 20b. The first curved portion 34f is radially disposed between the first tip portion 34c and the axially projecting portion 34e.

[0058] As stated, the axially projecting portion 34e of the first tooth 34 defines the first maximum axial width W1. The first tip portion 34c engages with the bicycle chain 22 and functions to guide the first tooth 34 into the outer link gap S2. Thus, the first tooth 34 has the first maximum axial width W1 defined in the axial direction. The first maximum axial width W1 is larger than the inner link gap S1 and smaller than the outer link gap S2. Thus, the first tooth 34 is configured to fit into the outer link gap S2 to engage with the bicycle chain 22. In other words, the first tooth 34 is configured as a wide tooth that accommodates the outer link plates 22b of the bicycle chain 22 during use.

[0059] Since the first tooth 34 is the wide tooth, the first maximum axial width W1 of the first tooth 34 defines a maximum axial width of the chain drive teeth 20 that includes a portion of the first and second axial surfaces 20a and 20b of the chain drive teeth 20. Thus, the chain drive teeth 20 have the maximum axial width at a portion of the at least one first axial surface 20a and the second axial surface 20b of the chain drive teeth 20. As will be discussed further below, in the preferred embodiment, the recess 38 is provided at the portion of the first axial surface 20a and the second axial surface 20b of the first tooth 34.

[0060] In the illustrated embodiment, the maximum axial width of the chain drive teeth 20 (or the first maximum axial width W1) is preferably greater than or equal to 2.5 millimeters and less than or equal to 5.4 millimeters. More preferably, the maximum axial width of the chain drive teeth 20 is greater than or equal to 3 millimeters and less than or equal to 4.5 millimeters.

[0061] How best in Fig. 3, the first maximum axial width W1 of the at least one first tooth 34 comprises a first axial percentage of the outer link gap S2 of the outer link plates 22b in the axial direction. In other words, the first maximum axial width W1 of the first tooth 34 occupies a percentage of the axial distance between the outer link plates 22b when the first tooth 34 engages the bicycle chain 22. In the embodiment shown, the first axial percentage is greater than or equal to 75 percent and less than or equal to 93 percent. That is, the first maximum axial width W1 of the first tooth 34 occupies 75 percent to 93 percent of the outer link gap S2 when it engages the outer link plates 22b.

[0062] During shifting, the axially projecting portion 34e having the first maximum axial width W1 receives a greater contact force from the bicycle chain 22, while the first tip portion 34c receives less contact force than the axially projecting portion 34e. Therefore, in the illustrated embodiment, the recess 38(s) and the lubricant are preferably provided on the axially projecting portion 34e of the first tooth 34, as will be discussed further below.

[0063] How best in Fig. 4, the second tooth 36 is designed as a narrow tooth compared to the first tooth 34. As shown in the Fig. 6 and Fig. As shown in Figure 7, the second tooth 36 includes a first edge 36a disposed adjacent a first circumferential surface, a second edge 36b disposed adjacent a second circumferential surface, and a second tip portion 36c circumferentially disposed between the first and second edges 36a and 36b. The first edge 36a, the second edge 36b, and an edge of the second tip portion 36c define an outer periphery 36d of the second tooth 36.

[0064] In the illustrated embodiment, the first and second axial surfaces 20a and 20b of the second tooth 36 comprise a second maximum axial width W2 of the second tooth 36, as discussed further below. The second tooth 36 further includes a second curved portion 36e, which is an arcuate surface formed on the first and second axial surfaces 20a and 20b of the second tooth 36. In the illustrated embodiment, the second curved portion 36e tapers more sharply than the first curved portion 34f of the first tooth 34.

[0065] As stated, the first and second axial surfaces 20a and 20b comprise the second maximum axial width W2 of the second tooth 36. In other words, a portion of the first and second axial surfaces 20a and 20b of the second tooth 36 comprises the second maximum axial width W2. The second tooth 36 thus has the second maximum axial width W2 defined in the axial direction. The second maximum axial width W2 is smaller than the first maximum axial width W1. The second maximum axial width W2 is smaller than the inner link gap S1. Thus, the second tooth 36 is configured to fit into the inner link plates 22a to engage the bicycle chain 22. The second maximum axial width W2 of the second tooth 36 comprises a second axial percentage of the inner link gap S1 of the inner link plates 22a in the axial direction.In other words, the second maximum axial width W2 of the second tooth 36 can fill a percentage of the axial spacing between the inner link plates 22a when the second tooth 36 engages the bicycle chain 22. In the illustrated embodiment, the second axial percentage is preferably greater than or equal to 75 percent and less than or equal to 93 percent. That is, the second maximum axial width W2 of the second tooth 36 can occupy 75 percent to 93 percent of the inner link spacing S1 when it engages the inner link plates 22a.

[0066] The recess 38 of the first illustrated embodiment will now be described with reference to the Fig. 6 and Fig. 7. As previously stated, the recess 38 is provided on the chain drive teeth 20 to store a lubricant to prevent wear and tear on the chain drive teeth 20. For example, in the preferred embodiment, as previously stated, the recess 38 is provided on the first and second axial surfaces 20a and 20b of the first tooth 34. In particular, as stated, the recess 38 may be provided on the axially projecting portion 34e of the first tooth 34 that defines the first maximum axial width W1, which also defines the maximum axial width of the chain drive teeth 20. In other words, the recess 38 is provided on a portion of an axial side surface of the first tooth 34 that defines the maximum axial width of the chain drive teeth 20, which is the first maximum axial width W1.Thus, in the preferred embodiment, the recess 38 is provided on at least one of the first axial surface 20a and the second axial surface 20b of the first tooth 34 (the wide tooth) to prevent wear and tear. As shown in FIGS. Fig. 6 and Fig. 7, the recess 38 is formed on both sides of the first axial surface 20a ( Fig. 6) and the second axial surface ( Fig. 7) 20b of the first tooth 34.

[0067] While in the illustrated embodiment, the recess 38 is shown as being provided on both the first and second axial surfaces 20a and 20b of the first tooth 34, it will be apparent to those skilled in the bicycle art from this disclosure that the recess 38 may be provided on only one of the first and second axial surfaces 20a and 20b of the first tooth 34. For example, the recess 38 may be provided on only the second axial surface 20b of the first tooth 34 (i.e., the axial surface farther from the bicycle frame when the bicycle sprocket 14 is mounted to the bicycle frame). In particular, the first tooth 34 may experience increased wear in the situation where a chainline between the rear cassette 12 and the bicycle sprocket 14 experiences an inward slope toward the bicycle frame extending from the bicycle sprocket 14 to the rear cassette 12 (as in Fig. 1). In this situation, the bicycle chain 22 is engaged with a largest rear cassette 12, as shown in Fig. 1. In this situation, when the bicycle chain 22 contacts the second axial surface 20b, the friction between the second axial surface 20b and the bicycle chain 22 is increased. In the inclined chain line situation, it is not necessary to provide the recess 38 on the first axial surface 20a. In this situation, the first axial surface 20a of the first tooth 34 is thus free of the recess 38. In other words, the first axial surface 20a of the first tooth 34 may be free of the recess 38, while the second axial surface 20b of the first tooth 34 includes the recess 38.

[0068] Alternatively, the recess 38 may be provided on both the first tooth 34 and the second tooth 36. As shown in the Fig. 6 and Fig. 7, the recess 38 is provided on at least one of the first axial surface 20a and the second axial surface 20b of the second tooth 36. While the illustrated embodiment shows the recess 38 provided on both the first and second axial surfaces 20a and 20b of the second tooth 36, it will be apparent to those skilled in the bicycle art from this disclosure that the recess 38 may be provided on only the second axial surface 20b, while the axial surface 20a is free of any recesses 38.

[0069] In the embodiment shown, the recess 38 preferably has a maximum depth defined by the first axial surface 20a and the second axial surface 20b along the axial direction relative to the central rotational axis X. In the embodiment shown, the maximum depth of the recess 38 is greater than or equal to 0.01 millimeters. Preferably, the maximum depth is less than or equal to 0.5 millimeters. More preferably, the maximum depth is less than or equal to 0.1 millimeters.

[0070] In the embodiment shown, as shown in Fig. As best seen in Figure 6, the recess 38 preferably has a maximum width M defined along the first axial surface 20a and the second axial surface 20b. In the illustrated embodiment, the maximum width of the recess 38 is greater than or equal to 0.01 millimeters. Preferably, the maximum width of the recess 38 is less than or equal to 2 millimeters. More preferably, the maximum width is approximately 0.05 millimeters.

[0071] The recess 38 may be formed using a mechanical process and / or a chemical process. Preferably, the recess 38 of the illustrated embodiment is formed by treating the axial surfaces 20a and 20b of the chain drive teeth 20 with an acid and / or chemical surface treatment, as shown in the Fig. 6 and Fig. 7. Alternatively, the recess 38 may be formed by stamping or deforming the first and second axial surfaces 20a and 20b of the chain drive teeth 20, as discussed below.

[0072] With reference to the Fig. 8 and Fig. 9, a portion of a first alternative bicycle sprocket 114 is shown, including a first tooth 134 and a second tooth 136. The first alternative bicycle sprocket 114 is identical in every respect to the bicycle sprocket 14, except that the first tooth 134 and the second tooth 136 are provided with modified recesses 138 created by a stamping process instead of a chemical process. Thus, portions and components of the first alternative bicycle sprocket 114 that are identical to the bicycle sprocket 14 are given the same reference numerals, but incremented by 100.

[0073] As in the Fig. 8 and Fig. 9, the first and second teeth 134 and 136 are provided with a plurality of recesses 138. However, as previously stated, the first tooth 134 and the second tooth 138 of the first modified bicycle sprocket 114 may also include a single recess 138.

[0074] With reference to the Fig. 10 and Fig. 11, a portion of a second alternative bicycle sprocket 214 is shown, including a first tooth 234 and a second tooth 236. The second alternative bicycle sprocket 214 is identical in every respect to the bicycle sprocket 114, except that each of the first tooth 234 and the second tooth 236 is provided with a single recess 238 having an elongated shape. Thus, portions and components of the second alternative bicycle sprocket 214 that are identical to the first alternative bicycle sprocket 114 are given the same reference numerals, but incremented by 100.

[0075] The recess 238 of the second modified bicycle sprocket 214 has an elongated profile defined by an outer edge 238a of the recess 238. Thus, as shown, the recess 238 extends in a circumferential direction about the rotational center axis X. As shown, the outer edge 238a of the recess 238 is located entirely within the outer edge 234d and 236d of the first and second teeth 234 and 236. Thus, the outer edge 238a of the recess 238 is located entirely within the outer edge of the first axial surface and the second axial surface 220a and 220b of the chain drive teeth 220. More specifically, in the embodiment shown, the outer edge 238a of the recess 238 formed on the first tooth 234 is located entirely within an outer edge of the axially projecting portion 234e. The recesses 238 are preferably created by a stamping or other mechanical process on the first and second teeth 234 and 236.

[0076] With reference to the Fig. 12 and Fig. 13, a portion of a third modified bicycle sprocket 314 is further shown, including a first tooth 334 and a second tooth 336. The third modified bicycle sprocket 314 is identical to the bicycle sprocket 114 in every respect, except that the first tooth 334 and the second tooth 336 are provided with a recess 338 having an irregular shape. Thus, portions and components of the third modified bicycle sprocket 114 that are identical to the first modified bicycle sprocket 114 are given the same reference numerals, but incremented by 200.

[0077] In particular, the profile of the recess 338 has a curved shape. Here, the profile of the recess 338 has a non-circular and non-polygonal shape. While the recess 338 has a non-circular and non-polygonal shape, it will be apparent to those skilled in the bicycle art from the present disclosure that the recess 338 may have a smooth outer edge. For example, the recess 338 may have a crescent shape, which may be symmetrical or non-symmetrical, as needed and / or desired. Preferably, the recess 338 is also created with a stamping or other mechanical forming process of the first and second teeth 334 and 336. Based on the examples provided, the recess (38, 238, and 338) may take on a variety of shapes and sizes.

[0078] As stated, the recesses (38, 238, and 338) of the illustrated embodiments store the lubricant. Examples of the lubricant include paraffin, oil, grease, and / or wax. When paraffin and wax are used, the paraffin and / or wax can be heated to 40°C, or the paraffin to 70°C, so that the paraffin is liquefied and can be better stored by the recesses (38, 238, and 338) of the illustrated embodiments. When acid is used to create the recess (e.g., recess 38), the lubricant is preferably oil.

[0079] In understanding the scope of the present invention, the term "comprising" and its derivatives, as used herein, are intended to be open-ended terms indicating the presence of the specified features, elements, etc. The foregoing also applies to words having similar meanings, such as "including," "comprising," and their derivatives. Also, unless otherwise indicated, the terms "part," "portion," "section," "component," or "element," when used in the singular, may have the dual meaning of a single part or a plurality of parts.

[0080] As used herein, the following directional terms: "frame-facing side," "non-frame-facing side," "forward," "backward," "front," "rear," "top," "bottom," "above," "below," "upward," "downward," "top," "bottom," "side," "vertical," "horizontal," "perpendicular," and "across," as well as any other similar directional terms, refer to the directions of a bicycle in an upright riding position equipped with the bicycle sprocket. Accordingly, these directional terms, as used to describe the bicycle sprocket, should be interpreted relative to a bicycle in an upright riding position on a horizontal surface equipped with the bicycle sprocket.The terms "left" and "right" are used to indicate "right" when referring to the right side as seen from the rear of the bicycle, and to indicate "left" when referring to the left side as seen from the rear of the bicycle.

[0081] Although only selected embodiments have been chosen to illustrate the present invention, it will be apparent to those skilled in the bicycle art from this disclosure that various changes and modifications may be made herein without departing from the scope of the invention as defined in the appended claims. For example, unless otherwise indicated, the size, shape, location, or orientation of the various components may be changed as needed and / or desired, so long as the changes do not materially affect their intended function. Unless specifically indicated otherwise, components shown as being directly connected or contacting one another may have intermediate structures disposed between them, so long as the changes do not materially affect their intended function.The functions of one element may be performed by two, and vice versa, unless specifically noted otherwise. The structures and functions of one embodiment may be incorporated into another embodiment. It is not necessary that all advantages be present in a particular embodiment.

Claims

[1] Bicycle sprocket (14, 114, 214, 314), comprising: a gear ring body (18) having a central axis of rotation (X); and a plurality of chain drive teeth (20, 220) extending radially outward from the sprocket body (18) to engage a bicycle chain (22), the plurality of chain drive teeth (20, 220) comprising a first axial surface (20a, 220a), a second axial surface (20b, 220b) opposite the first axial surface (20a, 220a) with respect to an axial direction of the central axis of rotation (X), at least one recess (38, 238, 338) provided on at least one of the first and second axial surfaces (20a, 20b, 220a, 220b) for storing a lubricant on the at least one of the first and second axial surfaces (20a, 20b, 220a, 220b), wherein the plurality of chain drive teeth (20, 220) comprises: at least one first tooth (34, 134, 234, 334) having a first maximum axial width (W1) defined in the axial direction; and at least one second tooth (36, 136, 236, 336) having a second maximum axial width (W2) defined in the axial direction, wherein the second maximum axial width (W2) is smaller than the first maximum axial width (W1). [2] The bicycle sprocket (14, 114, 214, 314) according to claim 1, wherein the first maximum axial width (W1) is larger than an inner link gap (S1) defined between an opposing pair of inner link plates (22a) of the bicycle chain (22) in the axial direction and smaller than an outer link gap (S2) defined between an opposing pair of outer link plates (22b) of the bicycle chain (22) in the axial direction, and the second maximum axial width (W2) is smaller than the inner link gap (S1). [3] Bicycle sprocket (14, 114, 214, 314) according to one of claims 1 or 2, wherein the first maximum axial width (W1) is greater than or equal to 2.5 millimeters and less than or equal to 5.4 millimeters. [4] Bicycle sprocket (14, 114, 214, 314) according to claim 3, wherein the first maximum axial width (W1) is greater than or equal to 3 millimeters and less than or equal to 4.5 millimeters. [5] Bicycle sprocket (14, 114, 214, 314) according to one of claims 1 to 4, wherein the first maximum axial width (W1) of the at least one first tooth (34, 134, 234, 334) has a first axial percentage of the outer link gap (S2) of the outer link plates (22b) in the axial direction, and the first axial percentage is greater than or equal to 75 percent and less than or equal to 93 percent. [6] Bicycle sprocket (14, 114, 214, 314) according to one of claims 1 to 5, wherein the second maximum axial width (W2) of the at least one second tooth (34, 36, 234, 334) has a second axial percentage of the inner link spacing of the inner link plates (22a) in the axial direction, and the second axial percentage is greater than or equal to 75 percent and less than or equal to 93 percent. [7] Bicycle sprocket (14, 114, 214, 314) according to one of claims 1 to 6, wherein the at least one recess (38, 238, 338) is provided on the at least one of the first axial surface (20a, 220a) and the second axial surface (20b, 220b) of the at least one first tooth (34, 134, 234, 334). [8] Bicycle sprocket (14, 114, 214, 314) according to one of claims 1 to 7, wherein the first axial surface (20a, 220a) is formed, in a state in which the bicycle sprocket (14, 114, 214, 314) is mounted on a bicycle frame, to be arranged closer to the bicycle frame in the axial direction than the second axial surface (20b, 220b), and the at least one recess (38, 238, 338) is provided on the second axial surface (20b, 220b) of the at least one first tooth (34, 134, 234, 334). [9] Bicycle sprocket (14, 114, 214, 314) according to claim 8, wherein the first axial surface (20a) of the at least one first tooth (34, 134, 234, 334) is free of the at least one recess (38, 238, 338). [10] Bicycle sprocket (14, 114, 214, 314) according to claim 8, wherein the at least one recess (38, 238, 338) is provided on both of the first axial surface (20a) and the second axial surface (20b, 220b) of the at least one first tooth (34, 134, 234, 334). [11] Bicycle sprocket (14, 114, 214, 314) according to one of claims 1 to 10, wherein the at least one recess (38, 238, 338) is provided on the at least one of the first axial surface (20a) and the second axial surface (20b, 220b) of the at least one second tooth (36, 136, 236, 336). [12] Bicycle sprocket (14, 114, 214, 314) according to one of claims 1 to 11, wherein the plurality of chain drive teeth (20, 220) has a maximum axial width at a portion of the at least one first axial surface (20a, 220a) and the second axial surface (20b, 220b), and the at least one recess (38, 238, 338) is provided at the portion of the at least one first axial surface (20a, 220a) and the second axial surface (20b, 220b). [13] Bicycle sprocket (14, 114, 214, 314) according to one of claims 1 to 12, wherein a maximum depth of the at least one recess (38, 238, 338) defined by the at least one of the first axial surface (20a, 220a) and the second axial surface (20b, 220b) is less than or equal to 0.5 millimeters. [14] Bicycle sprocket (14, 114, 214, 314) according to claim 13, wherein the maximum depth of the at least one recess (38, 238, 338) is greater than or equal to 0.01 millimeters. [15] Bicycle sprocket (14, 114, 214, 314), comprising: a gear ring body (18) having a central axis of rotation (X); and a plurality of chain drive teeth (20, 220) extending radially outward from the sprocket body (18) to engage a bicycle chain (22), the plurality of chain drive teeth (20, 220) comprising a first axial surface (20a, 220a), a second axial surface (20b, 220b) opposite the first axial surface (20a, 220a) with respect to an axial direction of the central axis of rotation (X), at least one recess (38, 238, 338) provided on at least one of the first and second axial surfaces (20a, 20b, 220a, 220b) for storing a lubricant on the at least one of the first and second axial surfaces (20a, 20b, 220a, 220b), wherein a maximum depth of the at least one recess (38, 238, 338) defined by the at least one of the first axial surface (20a, 220a) and the second axial surface (20b, 220b) is less than or equal to 0.5 millimeters and the maximum depth of the at least one recess (38, 238, 338) is greater than or equal to 0.01 millimeters. [16] Bicycle sprocket (14, 114, 214, 314) according to one of claims 1 to 15, wherein a maximum width (M) of the at least one recess (38, 238, 338) defined along the at least one of the first axial surface (20a, 220a) and the second axial surface (20b, 220b) is less than or equal to 2 millimeters. [17] Bicycle sprocket (14, 114, 214, 314) according to claim 16, wherein the maximum width (M) of the at least one recess (38, 238, 338) is greater than or equal to 0.01 millimeters. [18] Bicycle sprocket (14, 114, 214, 314) according to one of claims 1 to 17, wherein the plurality of chain drive teeth (20, 220) comprises a base material (40), and a wear-resistant layer (42) covering the base material (40), and at least one recess (38, 238, 338) is provided on the wear-resistant layer (42). [19] Bicycle sprocket (14, 114, 214, 314) according to claim 18, wherein the base material (40) comprises an aluminum alloy. [20] Bicycle sprocket (14, 114, 214, 314) according to one of claims 18 or 19, wherein the wear-resistant layer (42) comprises a ceramic material. [21] Bicycle sprocket (14, 114, 214, 314) according to one of claims 1 to 20, wherein the at least one recess (38, 238, 338) has an elongated profile defined by an outer edge (34d, 36d, 234d, 238a) of the at least one recess (38, 238, 338), and the at least one recess (38, 238, 338) extends in a circumferential direction about the central axis of rotation (X). [22] Bicycle sprocket (14, 114, 214, 314), comprising: a gear ring body (18) having a central axis of rotation (X); and a plurality of chain drive teeth (20, 220) extending radially outward from the sprocket body (18) to engage a bicycle chain (22), the plurality of chain drive teeth (20, 220) comprising a first axial surface (20a, 220a), a second axial surface (20b, 220b) opposite the first axial surface (20a, 220a) with respect to an axial direction of the central axis of rotation (X), at least one recess (38, 238, 338) provided on at least one of the first and second axial surfaces (20a, 20b, 220a, 220b) for storing a lubricant on the at least one of the first and second axial surfaces (20a, 20b, 220a, 220b) wherein the at least one recess (38, 238, 338) has an elongated profile defined by an outer edge (34d, 36d, 234d, 238a) of the at least one recess (38, 238, 338), and the at least one recess (38, 238, 338) extends in a circumferential direction about the central axis of rotation (X). [23] Bicycle sprocket (14, 114, 214, 314) according to claim 21 or 22, wherein the outer edge (34d, 36d, 234d, 238a) of the at least one recess (38, 238, 338) is disposed entirely within an outer edge (34d, 36d, 234d, 238a) of the at least one of the first axial surface (20a, 220a) and the second axial surface (20b, 220b) of the plurality of chain drive teeth (20, 220). [24] Bicycle sprocket (14, 114, 214, 314) according to one of claims 21 to 23, wherein the profile of the at least one recess (38, 238, 338) has a non-circular and non-polygonal shape. [25] Bicycle sprocket (14, 114, 214, 314) according to one of claims 21 to 24, wherein the profile of the at least one recess (38, 238, 338) has a curved shape. [26] Bicycle sprocket (14, 114, 214, 314) according to one of claims 1 to 25, wherein the plurality of chain drive teeth (20, 220) comprises at least thirty chain drive teeth (20, 220). [27] Bicycle sprocket (14, 114, 214, 314) according to one of claims 1 to 26, wherein the at least one recess (38, 238, 338) consists of only a single recess (38, 238, 338) provided on the at least one of the first and second axial surfaces (20a, 20b, 220a, 220b) of the plurality of chain drive teeth (20, 220). [28] Bicycle sprocket (14, 114, 214, 314) according to one of claims 1 to 27, further comprising a lubricant provided on the at least one recess (38, 238, 338).

Images