Bicycle chainring with shift assist tooth

Abstract

Bicycle chainring (S2, S3, S4, S5), including: a sprocket body (24) with a central axis of rotation (A); and a plurality of sprocket teeth (T1, T2, T3, T4, T4', T5, T6) extending radially outwards from a base circle (Rc) of the sprocket body (24), wherein the sprocket teeth (T1, T2, T3, T4, T4', T5, T6) are spaced circumferentially around the outer periphery of the sprocket body (24), wherein the chain- The gear teeth (T1, T2, T3, T4, T4', T5, T6) contain at least one shift assist tooth (T4, T4') which enables a shifting operation from the bicycle chainring (S2, S3, S4, S5) to a smaller sprocket, wherein the at least one shift assist tooth (T4, T4') has a maximum radial height when measured from the base circle (Rc) of the sprocket body (24), wherein the maximum radial height of the at least one shift assist tooth (T4, T4') is larger than a maximum radial height of most or a majority of the remaining chain sprocket teeth (T1, T2, T3, T5, T6) when measured from the base circle (Rc) of the sprocket body (24), and wherein the at least one shift assist tooth (T4, T4') has a downstream edge (61, 71), an upstream edge (62, 72), an upper side face (63, 73), a lower side face (64, 74) and a circumferential vertex face (65, 75), wherein the upper side face (63, 73) has a first inclined surface (63a, 73a) and a second inclined surface (63b, 73b), and wherein the first inclined surface (63a, 73a) of the upper side face (63, 73) of the at least one The shift assist tooth (T4, T4') is a radially inclined chain-guiding surface (63a, 73a), inclined towards the smaller sprocket, as is the radially inclined first inclined surface (63a,73a) radially towards the mean axis of rotation (A), and wherein the first inclined surface (63a, 73a) is inclined circumferentially in a downstream direction and radially in a lower sprocket-side direction, in the extent that the first inclined surface (63a, 73a) extends from the second inclined surface (63b, 73b) towards the downstream edge (61, 71) and the circumferential vertex surface (65, 75), and wherein the lower side surface (64, 74) has a first inclined surface (64a, 74a) and a second inclined surface (64b, 74b), wherein the first inclined surface (64a, 74a) is inclined radially in an upper sprocket-side direction, in the extent that the first inclined surface (64a, 74a) extends from the second inclined surface (64b, 74b) towards the circumferential vertex surface (65, 75), wherein the second inclined surface (64b, 74b) is circumferentially inclined in an upper sprocket-side direction,to the extent that the second inclined surface (64b, 74b) extends from the downstream edge (61, 71) to the upstream edge (62, 72).

Description

[0001] The present invention relates generally to a bicycle chainring. In particular, the present invention relates to a chainring with a shift assist tooth, which is mounted on a wheel of a bicycle, wherein the chainring has a tooth arrangement which provides smooth and reliable shifting.

[0002] Cycling is becoming increasingly popular, both as a leisure activity and as a means of transportation. Furthermore, cycling has become a very popular competitive sport, for both amateurs and professionals. Whether the bicycle is used for leisure, transportation, or competition, the bicycle industry is constantly striving to improve its various components. One component that has been intensively redesigned and further developed over the past few years is the bicycle's power transmission. In particular, bicycle component manufacturers have continuously sought to improve the shifting performance and characteristics of various shifting components, such as shifters, shift cables, derailleurs, chains, and chainrings.

[0003] A key component of power transmission, or the drivetrain, that has undergone significant improvements and redesign in recent years is the bicycle sprocket assembly. In particular, sprocket assemblies have been designed with improved sprockets to provide smoother and more fluid shifting. Specifically, the so-called Hyper-Glide sprocket assembly (HG rear sprocket assembly), described in US Patent No. 4,889,521 by Nagano, has been developed and marketed worldwide. This sprocket assembly has achieved high market penetration, and its technical design has established itself as an industry standard. The HG rear sprocket assembly, especially when used with a derailleur in road racing and mountain biking, has become an industry standard.

[0004] HG sprockets typically feature a chain guide surface on the side of the sprocket facing the smaller sprocket, with the exception of the smallest sprocket. This chain guide surface is designed to accommodate a coupling plate and a chain pin, allowing for significantly tighter chain guidance and smooth, jerk-free downshifting. Downshifting typically involves shifting from a smaller rear sprocket to a larger rear sprocket, thus reducing the gear ratio or providing a reduction in gearing. Two adjacent sprockets are arranged with a specific phase relationship relative to each other and to the chain guide surface. To maintain this phase relationship, each sprocket has spline or wedge surfaces formed on its inner periphery.One of the splines, spline surfaces, or wedge surfaces has a different shape than the other splines, spline surfaces, or wedge surfaces in order to guide the sprockets on matching splines, spline surfaces, or wedge surfaces on the outer body of a multi-speed freewheel or freewheel hub. The differently shaped splines, spline surfaces, or wedge surfaces ensure that adjacent sprockets are arranged or aligned in a suitable phase relationship.

[0005] A sprocket with a meshing tooth that assists in shifting from a bicycle sprocket to a larger sprocket, and a sprocket arrangement in which a sprocket has a radially inclined chain-guiding surface on the side facing a larger sprocket, is known from US 2006 / 0 154 767 A1. In this arrangement, a meshing tooth is provided whose maximum radial height is greater than the maximum radial height of the other sprocket teeth to ensure smooth downshifting. In contrast, a sprocket with three adjacent upshifting teeth is known from the translation of European patent DE 601 14 957 T2.The three adjacent upshift teeth are dimensioned in such a way as to prevent the bicycle chain from being shifted up when an outer chain link plate of the bicycle chain is engaged with the second upshift tooth, and to allow the bicycle chain to be shifted up when an inner chain link plate is engaged with the second upshift tooth.

[0006] The object of the present invention is to provide a sprocket for a sprocket arrangement to provide smooth or soft, reliable switching performance.

[0007] The aforementioned problem is solved by providing a bicycle chainring with a shift-assist tooth according to claim 1. The bicycle chainring with shift-assist tooth essentially comprises a chainring body and a plurality of chainring teeth. The chainring body has a central axis of rotation. The chainring teeth extend radially outward from a base or root circle of the chainring body, the chainring teeth being spaced circumferentially around the outer periphery of the chainring body. The chainring teeth include at least one shift-assist tooth that assists a shifting operation from the bicycle chainring to a smaller chainring. The at least one shift-assist or assist tooth has a maximum radial height when measured from the base or root circle of the chainring body.The maximum radial height of the at least one shift assist tooth is greater than the maximum radial height of a majority or a majority of the remaining sprocket teeth when measured from the base circle of the sprocket body. The at least one shift assist tooth has a radially inclined chain-guiding surface, inclined towards the small sprocket, as the radially inclined surface approaches the central axis of rotation radially.

[0008] With reference now to the accompanying drawings, which are part of the original revelation, the following applies: Fig. 1 is a side elevation view of a ten-stage sprocket arrangement, according to a preferred embodiment shown; Fig. Figure 2 is a cross-sectional view of the ten-stage sprocket arrangement, as seen along section line 1-1 of Fig. 1; Fig. Figure 3 is an exploded cross-sectional view of the ten-stage sprocket arrangement, as shown in Fig. 2 shown; Fig. 4 is a side elevation view of a side of one of the sprockets facing a small sprocket; Fig. 5 is a side elevation view of a side of one of the sprockets facing a large sprocket; Fig. Figure 6 is a partial side elevation view of the area containing a first engagement tooth and three teeth from the first engagement tooth downstream with respect to the direction of rotation of the bicycle chainring, with three chain rollers or pulleys shown in dashed lines to illustrate a downshift from a smaller gear (not shown) to the larger gear. Fig. Figure 7 is a partial side elevation view of the area or surface containing a shift assist or support tooth and a tooth on each side of the shift assist tooth with reference to the direction of rotation of the bicycle chainring. Fig. 8 is a partial external elevation view of a first intervention tooth of the in the Fig. 3 and Fig. 4. Sprocket shown, as seen from the side of the sprocket facing the small sprocket (shifting up). Fig. Figure 9 is a partial outer edge view of the first occlusal tooth, as shown in Fig. 8 shown, with regard to the in the Fig. 3 and Fig. 4 sprockets shown. Fig. 10 is a partial internal elevation view of the first intervention tooth, shown in the Fig. 8 and Fig. 9 regarding the in the Fig. 3 and Fig. 4. Sprocket shown as seen from the side of the sprocket facing the large sprocket (downshifting). Fig. Figure 11 is a partially downstream or downstream-facing edge elevation view of the first engagement tooth, shown in the Fig. 8 to Fig. 10, regarding the in the Fig. 3 and Fig. 4 chainring shown, as seen along an upstream direction with reference to the direction of rotation of the bicycle chainring. Fig. 12 is a partial external elevation view of a second intervention tooth of the in the Fig. 3 and Fig. 4. Sprocket shown, as seen from the side of the sprocket facing the small sprocket (shifting up). Fig. Figure 13 is a partial outer edge view of the second intervention tooth, as in Fig. 12 shown, regarding the one in the Fig. 3 and Fig. 4 sprockets shown. Fig. 14 is a partial internal elevation view of the second intervention tooth, shown in the Fig. 12 and Fig. 13 regarding the in the Fig. 3 and Fig. 4. Sprocket shown as seen from the side of the sprocket facing the large sprocket (downshifting). Fig. Figure 15 is a partially downstream or downstream-facing edge elevation view of the second engagement tooth, shown in the Fig. 12 to Fig. 14, regarding the in the Fig. 3 and Fig. 4. Chain wheel shown, as seen along an upstream direction with reference to the direction of rotation of the bicycle chain wheel. Fig. 16 is a partial external elevation view of a third occlusal tooth of the in the Fig. 3 and Fig. 4 shown chainring, as seen from the side of the chainring facing the small chainring (shifting up) or from the side of the chainring facing the small (upper) gear. Fig. 17 is a partial external elevation view of a third intervention tooth, shown in Fig. 16, regarding the in the Fig. 3 and Fig. 4 sprockets shown. Fig. Figure 18 is a partial internal elevation view of the third intervention tooth, shown in the Fig. 16 and Fig. 17 of the in the Fig. 3 and Fig. 4 sprocket shown, as seen from the side of the sprocket facing the large sprocket (downshifting) or as seen from the side of the sprocket facing the large (lower) sprocket. Fig. 19 is a partially downstream or directed edge elevation view of the third engagement tooth, shown in the Fig. 16 to Fig. 18, of the in the Fig. 3 and Fig. 4 chainring shown, as seen along an upstream direction with reference to the direction of rotation of the bicycle chainring. Fig. 20 is a partial external elevation view of a first shift-assisting tooth or a first shift-assisting tooth of the in the Fig. 3 and Fig. 4 shown chainring, as seen from the side of the chainring facing the small chainring (shifting up) or from the side of the chainring facing the small (upper) gear. Fig. Figure 21 is a partial outer edge view of the first shift support or assist tooth, shown in Fig. 20 regarding the in Fig. 3 and Fig. 4 sprockets shown. Fig. 22 is a partial internal elevation view of the first shift assist tooth, shown in the Fig. 20 and Fig. 21, of the Fig. 3 and Fig. 4 sprocket shown, as seen from the side of the sprocket facing the large sprocket (downshifting) or as seen from the side of the sprocket facing the large (lower) sprocket. Fig. 23 is a partially downstream or oriented edge elevation view of the first shift support or assist tooth, shown in the Fig. 20 to Fig. 22 regarding the in the Fig. 3 and Fig. 4 chainring shown, as seen along an upstream or directed direction with reference to the direction of rotation of the bicycle chainring. Fig. 24 is a partial external elevation view of a second shift assist tooth or a second shift support tooth of the in the Fig. 3 and Fig. 4 shown chainring, as seen from the side of the chainring facing the small chainring (shifting up) or as seen from the side of the chainring facing the smaller (upper) chainring. Fig. 25 is a partial outer edge view of the second shift assist tooth, shown in Fig. 24 regarding the in the Fig. 3 and Fig. 4 sprockets shown. Fig. 26 is a partial internal elevation view of the second shift assist tooth, shown in the Fig. 24 and Fig. 25, regarding the in the Fig. 3 and Fig. 4 sprocket shown, as seen from the side of the sprocket facing the large sprocket (downshifting) or as seen from the side of the sprocket facing the large (lower) sprocket. Fig. Figure 27 is a partially downstream or downstream edge elevation view of the second shift assist or support tooth, shown in the Fig. 24 to Fig. 26 regarding the in the Fig. 3 and Fig. 4 chainring shown, as seen along an upstream or directed direction with reference to the direction of rotation of the bicycle chainring. Fig. 28 is a partial external elevation view of an auxiliary or additional tooth of the in the Fig. 3 and Fig. 4 sprocket shown, as seen from the side of the sprocket facing the small sprocket or as seen from the side of the sprocket that is facing or points towards the small sprocket. Fig. Figure 29 is a partial outer edge view of the auxiliary or additional tooth, shown in Fig. 31 regarding the in the Fig. 3 and Fig. 4 sprockets shown. Fig. Figure 30 is a partial internal elevation view of the auxiliary or additional tooth, shown in the Fig. 28 and Fig. 29 of the in the Fig. 3 and Fig. 4 sprocket shown, as seen from the side of the sprocket facing the large sprocket (downshifting) or as seen from the side of the sprocket facing the large (lower) sprocket or from the side of the sprocket facing the large sprocket. Fig. 31 is a partial external elevation view of a tooth that is recessed or recessed on its upper side, of the tooth in the Fig. 3 and Fig. 4 sprocket shown, as seen from the side of the sprocket facing the small sprocket (upshifting) or as seen from the side of the sprocket facing the smaller (upper) sprocket or from the side of the sprocket facing the small sprocket. Fig. 32 is a partial outer edge view of the recessed area on the top side in the Fig. 31 tooth shown in Fig. 3 and Fig. 4 sprockets shown. Fig. Figure 33 is a partial internal elevation view of the upper tooth with the recess, as shown in the Fig. 31 and Fig. 32 regarding the in the Fig. 3 and Fig. 4 sprocket shown, as seen from the side of the sprocket facing the large sprocket (downshifting) or as seen from the side of the sprocket facing the large (lower) sprocket or from the side of the sprocket facing the large sprocket. Fig. 34 is a partially downstream or downstream edge elevation view of the upper surface recessed or recessed tooth, shown in the Fig. 31 to Fig. 33 regarding the in the Fig. 3 and Fig. 4 chainring shown, as seen along an upstream direction with reference to the direction of rotation of the bicycle chainring.

[0009] Selected embodiments of the present invention will now be explained with reference to the drawings.

[0010] Initially referring to the Fig. 1 to Fig. Figure 3 shows a multi-stage rear sprocket assembly 10 according to a first embodiment. In the illustrated embodiment, the multi-stage sprocket assembly 10 comprises a plurality of sprockets S1 to S10, a locking ring 12, a locking ring spacer 14, a first sprocket spacer 16, a second sprocket spacer 18, a first sprocket carrier 20, and a second sprocket carrier 22. The sprockets S1 to S10 are axially spaced from one another by a predetermined interval or distance. The sprockets S1 to S10 are configured to be fixedly mounted with respect to a freewheel (not shown) of a rear hub (not shown) in a relatively conventional manner, such that the sprockets S1 to S10 rotate together about a central axis of rotation A. The sprockets S1 to S10 typically rotate in a forward direction of rotation B, e.g.,in a clockwise direction as seen in . Fig. 1 (when the cyclist pedals forward, clockwise) to propel or move the bicycle in a forward direction.

[0011] As explained below, chainrings S2 to S5 have specially configured teeth that assist in shifting from a larger-diameter to a smaller-diameter chainring. Chainrings S1 and S6 to S10 can have relatively conventional teeth, as shown, or they can be modified to have specifically configured teeth that assist in shifting, depending on whether this is desired and / or necessary. It is obvious to anyone skilled in the art of bicycle technology, based on the present disclosure, that the chainring arrangement 10 can also have more or fewer chainrings than shown.In other words, chainring arrangement 10 can be any multi-stage chainring arrangement for a bicycle which uses a front derailleur or derailleur or the like and which includes at least one large chainring and at least one small chainring.

[0012] As it is in the Fig. 1 to Fig. Figure 3 shows that the sprockets S1 to S10 are hard, rigid, disc-shaped elements made of a suitable material, such as a metallic material. In the illustrated embodiment, the sprockets S1 to S10 are each a single, one-piece element made of a metallic material suitable for bicycle sprockets. In the illustrated embodiment, the sprocket S3, as can be seen in the Fig. 4 and Fig. 5 a basic tooth configuration, as also used in sprockets S2, S4 and S5. Basically, sprockets S2 to S5 differ only in their overall diameter, the number of teeth, the hub mounting structure and the size / number of weight reduction openings (where present). Of course, sprockets S2 to S5 may also differ from one another with respect to other features that are not related to the present invention.

[0013] With reference to Fig. Figure 2 shows the sprocket assembly 10 in partial cross-section with arrows indicating the directions for upshifting and downshifting. An upshift occurs when the chain moves from a large sprocket to the next smaller sprocket, whereas a downshift occurs when the chain moves from a small sprocket to the next larger sprocket. The sprockets S1 to S10 are designed to allow the chain to perform smooth upshifting and downshifting movements. In the illustrated embodiment, and as described above, the sprockets S1 and S6 to S10 are of conventional design, while the sprockets S2 to S5 have modified teeth to improve upshifting.Sprockets S1 to S10 have the following tooth configuration: 11T-13T-15T-17T-19T-21T-23T-26T-30T-34T. The axial spacing between sprockets S2 to S10 is approximately 2.35 millimeters, while the axial spacing between sprockets S1 and S2 is approximately 2.26 millimeters. The sprocket body of sprocket S1 has a thickness of approximately 1.96 millimeters, while the sprocket bodies of sprockets S2 to S10 have a thickness of approximately 1.6 millimeters.

[0014] With reference to the Fig. 4 and Fig. 5. Since parts of the sprockets S2 to S5 are essentially the same for each of the sprockets S2 to S5 with reference to the present invention, only the sprocket S3 will be described in greater detail herein. Furthermore, identical or corresponding teeth of the sprockets S2 to S5 are numbered with the same reference numerals. As can be seen in the Fig. 4 and Fig. 5 The sprocket S3 basically comprises a sprocket body 24, a freewheel or hub mounting structure 26 and a chain engagement structure 28. In the case of the sprocket S3, the sprocket body 24 is advantageously integrally designed with the mounting structure 26 and the chain engagement structure 28 as a single, one-piece element.

[0015] The mounting structure 26 of the sprocket S3 is a bore provided with splines or wedge surfaces, which defines the inner periphery of the sprocket body 24. It is obvious to those skilled in the art that, based on the present disclosure, the sprocket S3 can also have other types of mounting structures, which might be suitable for fixing the sprocket S3 to the bicycle hub. For example, it is known to those skilled in the art that, based on the present disclosure, a sprocket carrier can be used for the mounting structure of the sprocket S3, insofar as this should be desired and / or necessary.In any case, the mounting structure 26 of the sprocket S3 is advantageously provided as a plurality of spline surfaces or wedge surfaces, wherein one or more splines have / have a different shape, such that the spline surface(s) corresponding to the spline surface(s) engage with the sprocket mounting sleeve of the freewheel or the like in a known manner to fix the sprocket S3 in a predetermined rotational position with respect to the remaining sprockets. The sprocket mounting sleeve is in turn rotatably mounted with respect to a hub axle by means of a ball bearing and a one-way coupling, all in an essentially known manner.

[0016] The chain engagement structure 28 is formed at the outer periphery of the sprocket body 24. The chain engagement structure 28 comprises a plurality of sprocket teeth T1, T2, T3, T4, T4', T5, and T6, each with a plurality of recesses or base sections or root sections, interposed between the teeth T1, T2, T3, T4, T4', T5, and T6. Thus, the sprocket teeth T1, T2, T3, T4, T4', T5, and T6 extend radially outward from an outer periphery of the sprocket body 24, with the recesses or notches being interposed between the sprocket teeth T1, T2, T3, T4, T4', T5, and T6. Advantageously, the sprocket teeth T1, T2, T3, T4, T4', T5, and T6 are uniformly spaced relative to one another. Thus, the recesses or notches are arranged in an alternating manner between the sprocket teeth T1, T2, T3, T4, T4', T5 and T6 and are evenly spaced with respect to each other.In the case of sprocket S3, two of the teeth T1, two of the teeth T2, two of the teeth T3, two of the teeth T4, only one tooth T4', two of the teeth T5 and four of the teeth T6 are present. As explained below, these teeth T1, T2, T3, T4, T4', T5 and T6 are arranged to form two upshift paths and two downshift paths for each of the sprockets S2 to S5 (only sprocket S3 is shown in detail).

[0017] The sprocket tooth T1 shall hereinafter be referred to as the first engagement tooth T1, which is the first tooth that engages with the chain or catches it when the chain is shifted from a sprocket with a smaller diameter to a sprocket with a larger diameter (that is, during a downshifting process).

[0018] The sprocket tooth T2 will hereinafter be referred to as the second engagement tooth T2, which is the second tooth that engages the chain when the chain is shifted from a sprocket with a smaller diameter to a sprocket with a larger diameter (i.e., during a downshifting operation). The sprocket tooth T3 will hereinafter be referred to as the third engagement tooth T3, which is the third tooth that engages the chain when the chain is shifted from the sprocket with a smaller diameter to a sprocket with a larger diameter (i.e., during a downshifting operation).As explained below, the sprocket teeth T4 and T4' shall be referred to herein as shift assist teeth T4 and T4', as they assist or support an upshifting operation from a sprocket of larger diameter to a sprocket of smaller diameter. The sprocket teeth T5 shall be referred to herein as auxiliary or additional teeth T5. The sprocket teeth T6 shall be referred to herein as the recessed or setback tooth T6.

[0019] As this is in Fig. As shown in Figure 1, the sprockets S2 to S5 are arranged such that the first engagement teeth T1 are offset by a circumference to provide a suitable phase relationship between the sprockets S2 to S5. During an upshift from a larger diameter sprocket to a smaller diameter sprocket, the larger diameter sprocket is considered the originating sprocket, while the smaller diameter sprocket is considered the receiving sprocket. During a downshift, the smaller sprocket is considered the original sprocket, and the larger sprocket is considered the receiving sprocket.When the chain is shifted from an origin sprocket, such as sprocket S3, to the next smaller or larger sprocket, such as sprocket S2 or S4, the center point of the last roller of the chain engaged with the origin sprocket is called the disengagement or escape point. The center of the first roller of the chain engaging with the receiving sprocket is called the engagement point. The chain lies between the disengagement or escape point and the engagement point of the upshift or downshift path of the chain during the shifting process. In the case of sprocket S3, there are two upshift disengagement points (ES-up) and two upshift engagement points (EN-up), two downshift disengagement points (ES-down), and two downshift engagement points (EN-down).The angle formed by the disengagement point and the engagement point with respect to the center of the sprocket assembly 12 is defined as the phase angle between a pair of adjacent sprockets. During downshifting, this phase angle is referred to as the downshift phase angle, whereas during upshifting, this phase angle is referred to as the upshift phase angle.

[0020] As it is in Fig. As can be seen in Figure 4, the outer boundary of the sprocket body 24 is defined by a root or base circle with a base or root circle radius Rc. As is well known, the base or root circle Rc is a hypothetical circle defined by the bottom (radially innermost point) of the recesses or notches or root sections between the sprocket teeth T1, T2, T3, T4, T4', T5, and T6. Thus, the base or root section of a sprocket tooth extends radially downwards and inwards from the base or root circle Rc towards the central axis of rotation A. In the embodiment shown here, the sprocket body 24 of the sprocket S3 has a first side surface 24a ( Fig. 4), directed towards or pointing to a smaller chainring (shifting up / upper) and via a second side surface 24b ( Fig. 5) directed towards or pointing towards a large chainring (downshifting / lower). As shown in Fig. As shown in Figure 3, the sprocket body 24 of sprocket S3 has a median plane Pc that intersects the sprocket body 24 between the first and second side faces 24a and 24b of the root or base section of the sprocket body 24. The teeth T1, T2, T3, T4, T4', T5, and T6 have a tooth radius Ro, whereas the shift assist teeth T4 and T4' have a tooth radius Ra that is larger than the tooth radius Ro by a prescribed or predetermined value (for example, 3 mm ± 1 mm). The relationship between the base or root circle radius Rc with respect to tooth radius Ro and the tooth radius Ra with respect to sprockets S3, S4, and S5 can be found in Table 1 below. Tabelle 1 Kettenrad Anzahl an Zähnen (n) Pitch bzw. Aufteilung (360 / n) Basis- oderWurzelkreis(Rc) Zahnradius(Ro) Zahnradius T4(Ra) S3 15 24.0000 52.88 mm 61.68 mm 64.68 mm S4 17 21.1765 60.92 mm 69.72 mm 72.72 mm S5 19 18.9474 68.96 mm 77.76 mm 80.76 mm

[0021] As can be seen in the Fig. 4 and Fig. In section 5, the chainring 14 rotates in the direction of rotation D to drive a (not shown) bicycle chain in the drive direction. During a derailleur shift, the chain is moved from one of the chainrings S1 to S10 to the next adjacent chainring S1 to S10 by means of a derailleur, which moves the chain axially relative to the central axis of rotation A of the chainrings S1 to S10. Bicycle chains are generally well known, and therefore a detailed illustration and description of a bicycle chain is unnecessary here. Naturally, the bicycle chain is a continuous loop with numerous internal and external coupling plates, which are pivotally connected to each other by linkage pins and chain rollers.The distance from the center of each chain roller to the center of the next is approximately 1 / 2 inch (12.7 mm). This dimension is known as the chain pitch or spacing. The bicycle chain can be any chain used with a bicycle chainring. Therefore, the chain will not be described in greater detail here.

[0022] With reference to the Fig. 8 to Fig. In section 11, the first engagement tooth T1 will now be discussed in greater detail. In the case of the sprocket S3, there are two first engagement teeth T1. The first engagement tooth T1 is also considered the first downshift tooth, as it is designed to be the first downshift tooth to catch or fully engage the chain roller during a downshift operation. The first engagement tooth T1 has a downstream edge 31, an upstream edge 32, an upper side face 33, and a lower side face 34, as well as a circumferential tip or apex face 35. The upper side face 33 and the lower side face 34 define a base section of the first engagement tooth T1.

[0023] As this is shown in the Fig. 8 and Fig. As can be seen in Figure 9, the upper side surface 33 of the first engagement tooth T1 is provided with an inclined surface 33a, which is inclined circumferentially in an upstream direction towards the sprocket's central plane Pc, originating from the side surface 24a of the sprocket S3 facing the small sprocket. The inclined surface 33a forms an acute angle with the side surface 34a of the sprocket S3 facing the small sprocket. The base of the upper side surface 33 of the first engagement tooth T1 includes a recess 36 extending along the inclined surface 33a, the radial and axial dimensions of which increase with respect to the central axis of rotation A as, and to the extent, the recess 36 approaches the upstream edge 32 from the downstream edge 31.

[0024] As this is shown in the Fig. 9 and Fig. As can be seen in Figure 10, the lower side surface 34 of the first engagement tooth T1 is provided with a pair of inclined surfaces 34a and 34b. The inclined surface 34a is inclined circumferentially in a downstream direction and is inclined radially towards the upper sprocket in the extent that the inclined surface 34a extends from the inclined surface 34b towards the downstream edge 31 and the circumferential vertex surface 35. The inclined surface 34b is inclined radially towards the upper or larger sprocket in the extent that the inclined surface 34b extends from the side surface facing the large sprocket towards the inclined surface 34a.Thus, the inclined surface 33a and the inclined surfaces 34a and 34b cause the circumferential vertex surface 35 of the first engagement tooth T1 to be twisted, with the downstream edge being twisted near the side surface 24a of the sprocket 53 facing the smaller (upper / upshifting) sprocket, and the upstream edge being arranged near the sprocket center plane Pc.

[0025] Moving now to the Fig. 12 to Fig. In section 15, the second engagement tooth T2 will now be described in greater detail. In the case of the sprocket S3, two of the second engagement teeth T2 are provided. The second engagement tooth T2 is also considered the second downshift tooth, since it is designed to be the second downshift tooth that catches or fully engages the chain roller or pulley during a downshift operation. The second engagement tooth T2 has a downstream edge 41, an upstream edge 42, an upper side face 43, a lower side face 44, and a circumferential tip or apex face 45. The upper side face 43 and the lower side face 44 define a base section of the second engagement tooth T2.

[0026] As this is shown in the Fig. 12 and Fig. As can be seen in Figure 13, the upper side surface 43 of the second engagement tooth T2 has an inclined surface 43a, which is inclined or chamfered or slopes in a downstream direction towards the sprocket center plane Pc from the side surface 24a of the sprocket S3 facing the smaller sprocket. The inclined surface 43a also slopes radially towards the sprocket center plane Pc from the side surface 24a of the sprocket S3 facing the smaller sprocket. The inclined surface 43a forms an acute angle with the side surface 24a of the sprocket S3 facing the smaller sprocket.

[0027] As this is shown in the Fig. 13 and Fig. As can be seen in Figure 14, the lower side surface 44 of the second engagement tooth T2 is provided with a pair of inclined surfaces 44a and 44b. The inclined surface 44a slopes radially, or is radially chamfered or inclined, in a direction lateral to the upper sprocket if, or to the extent, the inclined surface 44a extends from the inclined surface 44b towards the circumferential tip or vertex surface 45. The inclined surface 44b slopes circumferentially, or is circumferentially inclined or inclined, in a direction lateral to the upper sprocket if, or to the extent, the inclined surface 44b extends from the downstream edge 41 towards the upstream edge 42.The base of the lower side surface 44 of the second engagement tooth T2 contains a recess 46 extending along the inclined surface 44b, the radial and axial dimensions of which increase with respect to the mean axis of rotation A as the recess 46 approaches the upstream edge 42 from the downstream edge 41. Thus, the inclined surfaces 44a and 44b cause the circumferential tip or vertex surface 45 of the second engagement tooth T2 to be offset towards the side surface 24a of the sprocket S3 facing the small (upper / upshifting) sprocket with respect to the sprocket center planes Pc.A recess such as recess 46 helps to carry out a smooth upshifting procedure, since the chain can be positioned closer to a smaller sprocket at the location of the second engagement tooth T2 during an upshifting operation, due to the presence of recess 46.

[0028] Moving now to the Fig. 16 to Fig. Section 19 describes a third engagement tooth T3 in greater detail. In the case of the sprocket S3, two third engagement teeth T3 are provided. The third engagement tooth T3 is also considered the third downshift tooth, as it is designed to be the third downshift tooth that engages the chain roller or pulley during a downshift operation or fully engages with it. The third engagement tooth T3 has a downstream edge 51, an upstream edge 52, an upper side surface 53, a lower side surface 54, and a circumferential tip or vertex surface 55. The upper side surface 53 and the lower side surface 54 define a base section of the third engagement tooth T3.

[0029] As it is in the Fig. 16 and Fig. As can be seen in Figure 17, the upper side surface 53 of the third engagement tooth T3 has an inclined surface 53a, which is radially inclined or slopes in a lower sprocket side direction towards the sprocket center plane Pc from the side surface 24a of the sprocket S3 facing the small sprocket. As shown in the Fig. 17 and Fig. As can be seen in Figure 18, the lower side surface 54 of the third engagement tooth T3 has a pair of inclined surfaces 54a and 54b. The inclined surface 54a is radially inclined or slopes downwards in the direction towards the upper sprocket or in a direction towards the upshift sprocket, if and to the extent that the inclined surface 54a extends from the inclined surface 54b towards the circumferential tip or apex surface 55. The inclined surface 54b is circumferentially inclined or slopes downwards in a direction towards the upper sprocket or in a direction towards the upshift sprocket, if and to the extent that the inclined surface 54b extends from the downstream edge 51 towards the upstream edge 52.The base of the lower side surface 54 of the third engagement tooth T3 contains a recess 56 extending along the inclined surface 54b, the radial and axial dimensions increasing with respect to the mean axis of rotation A as the recess 56 approaches the upstream edge 52 from the downstream edge 51. Thus, the inclined surfaces 54a and 54b cause the circumferential tip or vertex surface 55 of the third engagement tooth T3 to be offset relative to the side surface 24a facing the small sprocket and the side surface 24a facing the small sprocket and the upper (upshifting) sprocket, respectively, with respect to the sprocket S3 and the sprocket center plane Pc.Such a recess, like the recess 56, supports smooth upshifting or a smooth upshifting process, since the chain can be arranged or positioned closer to the smaller sprocket at the location of the third engagement tooth T3 during the upshifting process, due to the presence of the recess 56.

[0030] Moving now to the Fig. 20 to Fig. Section 23 will now discuss the shift assist or support tooth T4 in greater detail. In the case of the sprocket S3, two shift assist or support teeth T4 are provided. Although the shift assist tooth T4 is advantageously arranged following or after the third engagement tooth T3 in the upstream direction, the shift assist tooth T4 can also be arranged following the first engagement tooth T1 in the upstream direction or following the second engagement tooth T2 in the upstream direction. The shift assist tooth T4 has the same radial height as the shift assist tooth T4' with respect to a radial direction of the sprocket S3. The shift assist teeth T4 and T4' are larger than the other teeth with respect to a radial direction of the sprocket S3.Since the shift assist teeth T4 and T4' are larger than the other teeth, a chain contacts the shift assist teeth T4 and T4' earlier during an upshift operation compared to the case where the shift assist teeth are the same size (or smaller / shorter) than the other teeth at their radial height. The shift assist tooth T4 has a downstream edge 61, an upstream edge 62, a top side face 63, a bottom side face 64, and a circumferential tip or vertex face 65. The top side face 63 and the bottom side face 64 define a base section of the shift assist or assist tooth T4.

[0031] As this is shown in the Fig. 20 and Fig. As can be seen in Figure 21, the upper side surface 63 of the shift assist tooth T4 has a pair of inclined surfaces 63a and 63b. The inclined surface 63a is inclined or slopes downwards in a downstream direction and radially towards the lower sprocket, as it extends from the inclined surface 63b to the downstream edge 61 and the circumferential apex or vertex surface 65. The inclined surface 63a also slopes radially or is also radially inclined towards the sprocket median plane Pc from the side surface 24a of the sprocket S3 facing the smaller sprocket. Due to the presence of the inclined surface 63a, the shift assist tooth T4 can effectively guide the chain towards a smaller sprocket after contacting the chain during the upshifting process.The inclined surface 63b slopes radially downwards, or is radially inclined, in a direction towards the lower sprocket, if and to the extent that the inclined surface 63b extends from the side surface 24a facing the small sprocket towards the inclined surface 63a. During an upshifting operation, a chain is guided towards a smaller sprocket by the inclined surface 63a.

[0032] As this is shown in the Fig. 21 and Fig. As can be seen in Figure 22, the lower side surface 64 of the shift assist tooth T4 has a pair of inclined surfaces 64a and 64b. The inclined surface 64a slopes radially downwards or is radially inclined in a direction towards the upper sprocket or in a direction towards the upshift sprocket, respectively, if and to the extent that the inclined surface 64a extends from the inclined surface 64b towards the circumferential tip or apex surface 65. The inclined surface 64b slopes downwards or is circumferentially inclined in a direction towards the upper sprocket or in a direction towards the upshift sprocket, respectively, if and to the extent that the inclined surface 64b extends from the downstream edge 61 towards the upstream edge 62.The base of the lower side surface 64 of the shift assist tooth T4 contains a recess 66 extending along the inclined surface 64b, the radial and axial dimensions of which increase with respect to the central axis of rotation A as the recess 66 approaches the upstream edge 62 from the downstream edge 61. Thus, the inclined surfaces 64a and 64b cause the circumferential tip and apex surface 65 of the shift assist tooth T4 to be offset relative to the side surface 24a of the sprocket S3 facing the smaller (upper / upshifting) sprocket with respect to the sprocket's central plane Pc.The recess 66 helps or supports a smooth upshifting or a smooth or soft upshifting process, as the chain can be positioned or arranged closer to a smaller sprocket at the location of the shift assist tooth T4 during an upshifting process, due to the presence of the recess 66.

[0033] Moving on to the Fig. 24 to Fig. Section 27 will now discuss the shift assist tooth T4' in greater detail. In the case of the sprocket S3, there is only one shift assist tooth T4'. The shift assist tooth T4' has a downstream edge 71, an upstream edge 72, an upper side surface 73, and a lower side surface 74, as well as a circumferential tip or apex surface 75. The upper side surface 73 and the lower side surface 74 define a base section of the shift assist tooth T4'. The shift assist tooth T4' is similar to the shift assist tooth T4.

[0034] As this is shown in the Fig. 24 and Fig. As can be seen in Figure 25, the upper side surface 73 of the shift assist tooth T4' has a pair of inclined surfaces 73a and 73b, which are similar to the inclined surfaces 63a and 63b of the shift assist tooth T4. However, the inclinations of the inclined surfaces 73a and 73b are greater than those of the surfaces 63a and 63b of the shift assist tooth T4. The inclined surface 73a slopes downwards or is inclined downwards in a downstream direction and radially in a direction lateral to the lower sprocket, if and to the extent that the inclined surface 73a extends from the inclined surface 73b towards the downstream edge 71 and the circumferential apex or peak surface 75. The greater inclination of the inclined surface 73a allows the shift assist tooth T4' to guide a chain even more effectively towards a smaller sprocket after contacting the chain during the upshifting process.The inclined surface 73b slopes radially downwards, or is radially inclined, in a direction towards the lower sprocket, if and to the extent that the inclined surface 73b extends from the side surface 24a facing the small (upper / upshifting) sprocket towards the inclined surface 73a. The base of the shift assist tooth T4' is provided with a recess 76 along the downstream edge 71. During an upshifting operation, a chain is guided towards a smaller sprocket by the inclined surface 73a.

[0035] As this is shown in the Fig. 25 and Fig. As can be seen in Figure 26, the lower side surface 74 of the shift assist tooth T4' has a pair of inclined surfaces 74a and 74b, which are similar to inclined surfaces 64a and 64b of the shift assist tooth T4. However, the inclinations of the inclined surfaces 74a and 74b differ from the inclinations or skews of surfaces 63a and 63b of the shift assist tooth T4. The inclined surface 74a slopes radially downwards or is radially inclined in a direction lateral to the upper sprocket, in the same way as the inclined surface 74a extends from the inclined surface 74b to the circumferential tip or apex surface 75.The inclined surface 74b slopes radially downwards, or is radially inclined, in a direction lateral to the upper sprocket, if and to the extent that the inclined surface 74b extends from the side surface 24b of the sprocket S3 facing the larger (lower / downshifting) sprocket towards the inclined surface 74a. Thus, the inclined surfaces 73a, 73b, 74a and 74b result from the circumferential tip or apex surface 75 of the shift assist tooth T4' being offset towards the side surface 24b of the sprocket S3 facing the larger (lower / downshifting) sprocket with respect to the sprocket center plane Pc.

[0036] Moving now to the Fig. 28 to Fig. In section 30, the auxiliary or additional teeth T5 will now be briefly discussed. In the case of the sprocket S3, two auxiliary teeth T5 are provided. The auxiliary or additional tooth T5 has a downstream edge 81, an upstream edge 82, an upper side surface 83, a lower side surface 84, and a circumferential tip or vertex surface 85. The upper side surface 83 and the lower side surface 84 define a base section of the additional tooth T5. As can be seen in the Fig. 28 and Fig. 29, the upper side surface 83 of the auxiliary or supplementary tooth T5 is provided with a pair of inclined surfaces 83a and 83b. The inclined surface 83a slopes downwards or is inclined downwards in a downstream direction and radially in a direction towards the lower sprocket or downshift sprocket, if and to the extent that the inclined surface 83a extends from the inclined surface 83b towards the downstream edge 81 and the circumferential tip or apex surface 85. The inclined surface 83b slopes downwards or is inclined radially in a direction towards the lower sprocket or downshift sprocket, if and to the extent that the inclined surface 83b extends from the side surface 24a facing the smaller (upshift) sprocket towards the inclined surface 83a.The base of the auxiliary or additional tooth T5 is provided with a recess 86 along the downstream edge 81. During an upshifting process, a chain is guided towards a smaller sprocket due to the inclined surface 83a.

[0037] As this is shown in the Fig. 29 and Fig. As can be seen in Figure 30, the lower side surface 84 of the auxiliary or additional tooth T5 has a pair of inclined surfaces 84a and 84b. The inclined surface 84a slopes radially downwards or is radially inclined in a direction towards the upper sprocket or upshift sprocket, if and to the extent that the inclined surface 84a extends from the inclined surface 84b towards the circumferential tip or apex surface 85. The inclined surface 84b slopes circumferentially or is circumferentially inclined in an upstream direction and slopes radially downwards or is radially inclined in a direction towards the upper or upshift chainring, if and to the extent that the inclined surface 84b extends from the side surface 24b of the sprocket S3 facing the large (upshift) sprocket towards the inclined surface 84a.Thus, the inclined surfaces 83a, 83b, 84a and 84b result in the circumferential vertex surface 85 of the auxiliary or additional tooth T5 being offset towards the side surface 24b of the sprocket S3 facing the large (downshifting) sprocket with reference to the sprocket center plane Pc.

[0038] Moving now to the Fig. 31 to Fig. In section 34, the upper-cut tooth T6 will now be described in greater detail. In the case of the sprocket S3, four upper-cut teeth T6 are provided, with the upper-cut teeth T6 being grouped into two pairs of upper-cut or recessed teeth T6. The upper-cut tooth T6 has a downstream edge 91, an upstream edge 92, an upper side surface 93, a lower side surface 94, and a circumferential tip or apex surface 95. The upper side surface 93 and the lower side surface 94 define a base section of the upper-cut tooth T6. A recess 96 extends along the base of each of the pairs of upper-cut teeth T6 to assist downshifting to a larger sprocket. The recess 96 is provided to position a chain closer to a larger sprocket during a downshifting operation.Thus, a cutout (i.e., a toothless section) could also be provided by simply removing the upper surface recessed tooth T6 instead of providing the recess 96 on the base section of the upper surface recessed tooth T6.

[0039] As this is shown in the Fig. 31 and Fig. As can be seen in Figure 32, the tooth T6, which has a recess on its upper surface, has a pair of inclined surfaces 93a and 93b and a non-inclined surface 93c. The inclined surface 93a slopes downwards or is inclined downwards in a downstream direction and slopes downwards or is inclined radially towards the lower sprocket in the same direction as the inclined surface 93a extends from the non-inclined surface 93c towards the downstream edge 91 and the circumferential apex surface 95. The inclined surface 93b slopes downwards or is inclined radially towards the lower sprocket in the same direction as the inclined surface 93b extends from the non-inclined surface 93c towards the circumferential apex surface 95.The non-inclined surface 93c is parallel to the sprocket's median plane Pc and to the side surfaces 24a and 24b of the sprocket S3. The non-inclined surface 93c is offset from the side surface 24a of the sprocket S3, which faces the smaller (upper / upshifting) sprocket, towards the sprocket's median plane Pc, due to the recess 96 in the base section of the sprocket body 24. As can be seen in the figures. Fig. 32 and Fig. 33 is the lower side surface 94 of the upper surface recessed tooth T6 provided with an inclined surface 94a, which drops radially or is inclined in a direction towards the upper sprocket or upshift sprocket if or to the extent that the inclined surface 94a extends from the side surface 24b of the sprocket S3 directed towards the larger (upper / upshift) or upshift sprocket towards the circumferential tip or apex surface 95.

[0040] To better understand the above description of the chainring arrangement 10, some of the terms are now further explained for the purpose of improving clarity. As used herein, the terms "forward," "backward," "above," "below," "lateral," and "transverse," as well as similar directional terms, are intended to indicate such directions of the chainring arrangement 10 with respect to a bicycle in its normal riding position on a horizontal surface. Accordingly, directional terms as used herein are also to be understood as referring to the chainring arrangement 10 described in the claims, using an interpretation relative to a bicycle in its normal riding position on a horizontal surface.The terms ‘downshift’ and ‘upshift’ as used herein are also intended to refer to a rear sprocket arrangement 10 and should be interpreted and understood to mean a shifting operation from a smaller to a larger sprocket and from a larger to a smaller sprocket, as indicated by the arrows in . Fig.2. Furthermore, terms such as "phase relationship," "phase relationship ratio," and "angular phase relationship," as used herein, shall be understood as referring to angular relationships such as those existing between a pair of adjacent sprockets. As used herein, the term "smaller sprocket" refers to a sprocket with a smaller diameter relative to the sprocket in question or subject to stress, and the term "larger sprocket" refers to a sprocket with a larger diameter relative to the sprocket in question.As used herein, the term "side face facing the smaller sprocket" shall mean the side face of the sprocket in question which faces a sprocket with a smaller diameter relative to the sprocket in question, and the term "side face facing the larger sprocket" shall refer to a side face of the sprocket in question that faces opposite or faces a sprocket with a larger diameter relative to the sprocket in question. As used herein, the terms "radially inclined" or "radially sloping" or "skew" and the like shall refer to inclinations or skews that exist in a radial direction relative to the sprocket's center plane, as seen along the plane of section that is perpendicular to the sprocket's center plane and passes through the central axis of rotation of the sprocket in question.As used herein, the terms "circumferentially inclined," "circumferentially sloping," and the like shall refer to inclinations or slopes, or a downward slope, in a circumferential direction with respect to the sprocket plane, as seen along a section plane perpendicular to the sprocket's median plane and passing through the median axis of rotation of the sprocket under consideration. As used herein, the term "adjacent tooth" shall refer to an immediately adjacent tooth with respect to a tooth in question, with no other teeth interposed between the adjacent tooth and the tooth in question. The absence of the use of modified terms, such as "at least one" preceding another term, should be interpreted as meaning that an additional term of the same kind is not required.As used here, the term "at least one" should not be used to exclude other terms. Therefore, "first intervention tooth" and "at least one of the first intervention teeth" should both be interpreted to indicate that there could be more than one first intervention tooth.

Claims

[1] Bicycle chainring (S2, S3, S4, S5), comprising: a sprocket body (24) with a central axis of rotation (A); and a plurality of sprocket teeth (T1, T2, T3, T4, T4', T5, T6) extending radially outwards from a base circle (Rc) of the sprocket body (24), wherein the sprocket teeth (T1, T2, T3, T4, T4', T5, T6) are spaced circumferentially around the outer periphery of the sprocket body (24), wherein the chain- The gear teeth (T1, T2, T3, T4, T4', T5, T6) contain at least one shift assist tooth (T4, T4') which enables a shifting operation from the bicycle chainring (S2, S3, S4, S5) to a smaller sprocket, wherein the at least one shift assist tooth (T4, T4') has a maximum radial height when measured from the base circle (Rc) of the sprocket body (24), wherein the maximum radial height of the at least one shift assist tooth (T4, T4') is larger than a maximum radial height of most or a majority of the remaining chain sprocket teeth (T1, T2, T3, T5, T6) when measured from the base circle (Rc) of the sprocket body (24), and wherein the at least one shift assist tooth (T4, T4') has a downstream edge (61, 71), an upstream edge (62, 72), an upper side face (63, 73), a lower side face (64, 74) and a circumferential vertex face (65, 75), wherein the upper side face (63, 73) has a first inclined surface (63a, 73a) and a second inclined surface (63b, 73b), and wherein the first inclined surface (63a, 73a) of the upper side face (63, 73) of the at least one The shift assist tooth (T4, T4') is a radially inclined chain-guiding surface (63a, 73a), inclined towards the smaller sprocket, as is the radially inclined first inclined surface (63a,73a) radially towards the mean axis of rotation (A), and wherein the first inclined surface (63a, 73a) is inclined circumferentially in a downstream direction and radially in a lower sprocket-side direction, in the extent that the first inclined surface (63a, 73a) extends from the second inclined surface (63b, 73b) towards the downstream edge (61, 71) and the circumferential vertex surface (65, 75), and wherein the lower side surface (64, 74) has a first inclined surface (64a, 74a) and a second inclined surface (64b, 74b), wherein the first inclined surface (64a, 74a) is inclined radially in an upper sprocket-side direction, in the extent that the first inclined surface (64a, 74a) extends from the second inclined surface (64b, 74b) towards the circumferential vertex surface (65, 75), wherein the second inclined surface (64b, 74b) is circumferentially inclined in an upper sprocket-side direction,to the extent that the second inclined surface (64b, 74b) extends from the downstream edge (61, 71) to the upstream edge (62, 72). [2] Bicycle chainring (S2, S3, S4, S5) according to claim 1, in which at least two shift assist teeth (T4, T4') are included. [3] Bicycle chainring (S2, S3, S4, S5) according to claim 2, wherein the at least two shift assist teeth (T4, T4') are identical. [4] Bicycle chainring (S2, S3, S4, S5) according to claim 2 or 3, wherein the at least two shift assist teeth (T4, T4') are consecutive teeth. [5] Bicycle chainring (S2, S3, S4, S5) according to one of claims 2 to 3, wherein the at least two shift assist teeth (T4, T4') are not consecutive teeth. [6] Bicycle chainring (S2, S3, S4, S5) according to any one of claims 1 to 5, wherein the chainring teeth (T1, T2, T3, T4, T4', T5, T6) include a first engagement tooth (T1) which engages when a bicycle chain is shifted from the chainring (S2, S3, S4, S5) to a larger chainring, wherein the at least one shift assist tooth (T4, T4') is arranged within five teeth of the first engagement tooth (T1) in an upstream direction with respect to a direction of rotation (D) of the bicycle chainring (S2, S3, S4, S5). [7] Bicycle chainring (S2, S3, S4, S5) according to claim 6, wherein the chainring teeth (T2, T3, T5, T6) include a recessed section formed in a base section of a side surface of the chainring body (24) facing the smaller chainring at a tooth of the chainring teeth (T2, T3, T5, T6) adjacent to the first engagement tooth (T1) in a downstream direction with reference to the direction of rotation (D) of the bicycle chainring (S2, S3, S4, S5). [8] Bicycle chainring (S2, S3, S4, S5) according to claim 6 or 7, wherein the chainring teeth (T2, T3, T5, T6) include a recessed section formed in a base section of a side surface of the chainring body (24) facing the larger chainring at a tooth of the chainring teeth (T2, T3, T5, T6) which is located downstream of the at least one shift assist tooth (T4, T4') in a downstream direction with reference to the direction of rotation (D) of the bicycle chainring and upstream of the first engagement tooth (T1) in the upstream direction with reference to the direction of rotation (D) of the bicycle chainring (S2, S3, S4, S5). [9] Bicycle chainring (S2, S3, S4, S5) according to one of claims 6 to 8, wherein the chainring teeth (T2, T3, T5, T6) include a recessed section formed in a base section of a side surface of the chainring body (24) facing the larger chainring at one tooth of the chainring teeth (T2, T3, T5, T6), in the present case within two teeth of the at least one shift assist tooth (T4, T4') in a downstream direction with reference to the direction of rotation (D) of the bicycle chainring (S2, S3, S4, S5). [10] Bicycle chainring (S2, S3, S4, S5) according to one of claims 6 to 9 in which the chainring teeth (T2, T3, T5, T6) include a recessed section formed in a base section of a side surface of the chainring body (24) facing the larger chainring at a tooth of the chainring teeth (T2, T3, T5, T6) adjacent to the at least one shift assist tooth (T4, T4') in a downstream direction with reference to the direction of rotation (D) of the bicycle chainring (S2, S3, S4, S5). [11] Bicycle chainring (S2, S3, S4, S5) according to any one of claims 6 to 10, wherein the chainring teeth (T2, T3, T5, T6) contain two successive recessed sections formed in a base or root section of a side surface of the chainring body (24) facing the larger chainring at two successive teeth of the chainring teeth (T2, T3, T5, T6), wherein the two successive teeth (T2, T3, T5, T6) are arranged successively adjacent to the at least one shift assist tooth (T4, T4') in a downstream direction with reference to the direction of rotation (D) of the bicycle chainring (S2, S3, S4, S5).

Images