Pinion for a bicycle transmission

Abstract

The invention relates to a pinion for a bicycle transmission, comprising an outer ring with external toothing for engaging with a bicycle chain, an inner ring arranged coaxially with the outer ring and rotationally fixed to the outer ring, and a circumferential flange integrally formed with the inner ring and protruding axially to one side of the inner ring, the flange being constructed as a continuous flange. On the radially inner side of the flange, an inner profile is provided, which has a plurality of radially inwardly protruding radial protrusions, and on the radially outer side of the flange, an outer profile is provided, which has a plurality of radial recesses, the number and arrangement of which correspond to the number and arrangement of the radial protrusions of the inner profile. The invention also relates to a method for manufacturing such a pinion.

Description

TECHNICAL FIELD

[0001] The invention relates to a sprocket for a bicycle transmission, in particular to a sprocket comprising an outer ring with external toothing for engaging with a bicycle chain, an inner ring arranged coaxially to the outer ring and rotationally fixed to the outer ring, and a circumferential flange integrally formed with the inner ring and protruding axially to one side of the inner ring, the flange being constructed as a continuous flange. On the radially inner side of the flange an inner profile is provided, which has a plurality of radially inwardly protruding radial protrusions. BACKGROUND

[0002] The term sprocket shall here mean both a rear sprocket in the narrow sense, i.e. a sprocket adapted to transmit a torque to a rear hub of a bicycle, and a front sprocket or toothed disc, which is adapted to receive a torque from a pedal crank of a bicycle and to transmit this torque to a transmission and thus to a rear wheel of the bicycle via a bicycle chain and a rear sprocket engaging with this bicycle chain.

[0003] The inner profile of such a sprocket has to fulfill different requirements. Thus, the minimum radial dimension or area of the protrusions of the inner profile is mainly generated by the material of the sprocket and the material of the component to be coupled with the sprocket for torque transmission in the mounted state, and by the existing requirements for the torque to be transmitted and the duration of the load.

[0004] If the radial dimension of the protrusions is too small, or in other words, if the depth of the inner profile is too small, the load flanks of the sprocket or / and of the aforementioned component to be coupled with the sprocket can be deformed undesirably in operation.

[0005] The flange has to provide an axial support surface as well, which supports a bicycle component resting thereon, so that no deformation occurs in the running operation or no excessive influence on the tightening torque occurs when mounting the sprocket or a sprocket freewheel.

[0006] In practice, the aforementioned sprockets of the same type have been manufactured so far that in a forming process also called "flange stretching", a flange is first manufactured having a rounded radial inner surface and a rounded radial outer surface. Subsequently, the inner profile is cut into the radially inner side of the flange, wherein the radial outer surface of the flange remains rounded.

[0007] In order to make the aforementioned surface of the flange for axial support and in particular for torque transmission on the inner profile large enough, material has to be removed in the known sprockets, so that the amount of material for manufacturing the sprocket is large. SUMMARY

[0008] In view of the prior art described above, it is the object of the first aspect of the application to provide a pinion which can be produced in a material-saving manner and which has good torque transmission properties.

[0009] The solution according to the application to achieve the above object is that on the radially outer side of the flange there is likewise provided an outer form having a plurality of radial recesses, which correspond to the number and arrangement of the radial protrusions of the inner form.

[0010] It is thus possible to produce at least one preform of the final inner form together with the outer form in a forming process in which only the material is redistributed, but not removed.

[0011] Although material is also removed afterwards in order to produce the desired profile shape and / or profile depth, the amount of material which has to be removed afterwards can be reduced compared to a pinion of the same type in which the inner form is produced only by material removal, so that the necessary material outlay is reduced.

[0012] The terms radial, axial, coaxial and the like in this context relate to the central axis of the pinion, which in operation also corresponds to the axis of rotation of the pinion.

[0013] In the pinion according to the application, the inner ring and the outer ring are preferably formed integrally.

[0014] The thickness of the inner ring, i.e. its axial dimension, can be for example 1.5 mm to 2 mm, preferably 1.6 mm to 1.8 mm. The flange can protrude in the axial direction by a few millimeters from the inner ring, so that the axial dimension of the pinion at the central opening is for example 2.5 mm to 8 mm, preferably 3 to 7 mm, particularly preferably 3.3 mm to 6.5 mm. The aforementioned axial dimension corresponds approximately to the axial extension of the inner form minus a minimum correction based on the rounded edge.

[0015] Preferably, the pinion according to the application is used as a rear pinion. In this case, the protrusions of the inner form of the circumferential flange serve as transmission elements, which are suitable for transmitting torque from the pinion to a transmission on the rear hub of the bicycle.

[0016] Alternatively, the pinion according to the application is used as a front pinion or as a sprocket, in which case the protrusions of the inner form of the circumferential flange are suitable for transmitting torque from the pedal crank or a component connected thereto to the protrusions.

[0017] In both cases, the circumferential flange protrudes in the axial direction inwards, i.e. towards the side closer to the centre plane of the wheel of the bicycle, from the inner ring in the state in which the pinion is mounted on the bicycle. However, it cannot be ruled out that in both of the aforementioned cases the pinion is mounted in such a way that the circumferential flange protrudes in the axial direction outwards from the inner ring, for example in the case of the flange serving as a spacer to an adjacent pinion.

[0018] According to one preferred refinement, each of the inwardly projecting portions can have a first toothing which is arranged in front with respect to a predetermined direction of rotation about the central axis of the pinion and a second toothing which is arranged behind with respect to the predetermined direction of rotation, wherein the first toothing and the second toothing are not mirror-symmetrical for at least one, preferably for a plurality, in particular for each of the inwardly projecting portions.

[0019] Thus, in a configuration in which torque is transmitted only in one direction of rotation, for example in a freewheel, it is possible to achieve a sufficiently large surface of the first toothing which serves as a load toothing for the transmission of torque, while at the same time reducing the risk of tilting by means of the second toothing or the corresponding smaller surface of the counter toothing.

[0020] To this end, the first toothing of the at least one inwardly projecting portion can have a greater length in the radial direction than the second toothing. This preferably applies to a plurality of the inwardly projecting portions, in particular to each of the inwardly projecting portions. The radial length of the second toothing can be, for example, 75% or less, preferably 66% or less, of the radial length of the first toothing.

[0021] If the pinion of the application is used as a rear pinion, the predetermined direction of rotation is preferably the forward direction of rotation, and if the pinion is used as a sprocket, the predetermined direction of rotation is preferably the reverse direction of rotation, since in each of these cases the first toothing is always the load toothing for the transmission of torque.

[0022] In order to position the outer toothing of the pinion in the vicinity of the rear wheel in a space-saving and aerodynamically advantageous manner in the axial direction, the central plane of the outer toothing can be spaced apart in the axial direction from the central plane of the inner ring in order to mesh with the central plane of the bicycle chain or the outer ring. In particular preferably, the axial end face of the circumferential flange is arranged in the axial direction between the central plane of the inner ring and the central plane of the outer toothing or the central plane of the outer ring.

[0023] The pinion of the application can be used, for example, as the final pinion of a pinion freewheel, that is to say as the only pinion of the pinion set which is suitable for directly transmitting torque to the hub of the rear wheel of the bicycle.

[0024] Alternatively, however, the pinion can also be designed as a single pinion or as a plug-in pinion. In the latter case, a plurality or all of the pinions of the pinion set can be designed as pinions of the application, which each mesh with the transmission for the transmission of torque. The flange of the pinion of the application which projects axially to one side can at the same time serve as a spacer, thereby reducing the number of necessary components.

[0025] Therefore, a pinion for a bicycle transmission flywheel is likewise requested for protection, said pinion flywheel comprising a pinion set having a plurality of coaxially arranged, axially mutually spaced and rotationally connected pinions of different diameters, wherein one of these pinions is a final pinion which is adapted to directly transmit torque to a transmission on a rear wheel hub of a bicycle, and wherein said final pinion is as previously described a pinion of the invention.

[0026] Furthermore, a bicycle transmission is likewise requested for protection, having a transmission and at least one pinion of the invention, preferably a plurality of pinions of the invention, or having the aforementioned pinion flywheel.

[0027] According to a second aspect of the invention, the invention likewise relates to a method for manufacturing a pinion for a bicycle transmission, comprising the following steps:

[0028] i) punching out a pinion blank having a central pre-punching, and

[0029] ii) further processing the pinion blank into a pinion having a central opening, an inner ring and a circumferential flange integrally formed with said inner ring and axially protruding from said inner ring to one side, preferably a pinion of the invention as previously described, wherein step ii) comprises the following steps:

[0030] a) forming the pinion blank, wherein a punch is pressed through the pre-punching of the pinion blank into a die to form the circumferential flange.

[0031] According to the second aspect of the invention, the solution to the object of the invention as set out in the opening paragraph is a method having the features of the method as described above.

[0032] According to the invention, by forming the pinion blank in step a), an inner profile having a plurality of radially inwardly protruding radial protrusions is formed on the radially inner side of the flange, and an outer profile having a plurality of radial recesses is formed on the radially outer side of the flange, which recesses correspond to the number and arrangement of the radial protrusions of the inner profile.

[0033] The above description of the device includes method aspects and vice versa, so that the above description is to be supplemented by the foregoing.

[0034] In step i), the central pre-punching is preferably not round, but is constructed such that it has a plurality of radially inwardly protruding protrusions, which correspond to the number and arrangement of the radially inwardly protruding radial protrusions of the inner profile of the flange which is subsequently formed, so that a simple and more uniform material redistribution is achieved in the subsequent forming step.

[0035] In this case, at least one precursor of the outer shape and the inner shape of the flange or of the inner shape of the flange is produced, for example, by means of a suitable forming punch and a die.

[0036] According to a preferred embodiment, step ii) can also comprise a step b) after step a), in which the inner shape of the circumferential flange produced in the forming process is reworked, for example, by means of cutting or milling.

[0037] For example, surfaces which are particularly sensitive to tolerances, in particular surfaces which, in the installed state, are in direct contact with the transmission, are reworked.

[0038] In particular, the two tooth flanks of at least one protrusion which can be produced in this reworking step b) are asymmetric with respect to the pinion.

[0039] Accordingly, for at least one of the protrusions of the inner shape, preferably for a plurality of the protrusions, particularly preferably for each of the protrusions, the first tooth flank arranged in front with respect to the selected direction of rotation or / and the second tooth flank arranged behind with respect to the selected direction of rotation of the protrusion can be reworked in such a way that, after the reworking, the length of the first tooth flank in the radial direction is greater than the length of the second tooth flank.

[0040] The forming process for the flange can be carried out in several stages, for example, step a) preferably also comprises a further forming step a2) after a first forming step a1) for forming the flange with the inner shape and the outer shape, in which the pinion blank or the pinion is further formed in order to set the predetermined axial dimension of the flange.

[0041] For this purpose, the die used in the first forming step can be replaced by a modified die. In this way, the flatness of the axial end face of the flange can also preferably be set. If desired, the punch used in the first forming step can also be replaced in the forming step a2).

[0042] Incidentally, it should be mentioned that the aforementioned technique is equally suitable for producing a disc brake rotor of a bicycle. BRIEF DESCRIPTION OF DRAWINGS

[0043] The application will be explained in detail below with reference to the preferred embodiments shown in the drawings. In which:

[0044] Figure 1 is a side view of a bicycle with a pinion according to a preferred embodiment of the application,

[0045] Figure 2 is Figure 1 is a top view of the pinion according to a preferred embodiment of the application from the back side looking towards the pinion,

[0046] Figure 2a is a close-up view of the object in Figure 2 ,

[0047] Figure 3 is a top view of the object in Figure 2 from the front side onto the pinion,

[0048] Figure 4 is a perspective view of the object in Figure 2 ,

[0049] Figure 5 is a sectional view of the object in Figure 3 with the section indicated by V-V,

[0050] Figure 6 is an enlarged view of the area indicated by A in Figure 5 ,

[0051] Figure 7 is a partial close-up of the partial sectional perspective view of the object in Figures 2 to 6 ,

[0052] Figure 8 is another close-up view of the object in Figure 2 , which shows the tooth surface shape of the protrusion of the inner profile,

[0053] Figure 9 is a partial sectional perspective view of a pinion flywheel according to a preferred embodiment of the present application, wherein Figures 2 to 8 the pinion shown is embedded as a final pinion,

[0054] Figure 10 is a flow chart for illustrating a method according to a preferred embodiment of the present application,

[0055] Figure 11 is a schematic view of a pinion blank produced as an intermediate product in the method shown in Figure 10 ,

[0056] Figure 12 in sub-view a) a mold applied in a shaping step of the method shown in Figure 10 , and a cross-sectional view of a pinion shaped therein, in sub-view b) a partial close-up view of the area indicated by Z in sub-view a), and

[0057] Figure 13 in sub-view a) a mold applied in a further shaping step of the method shown in Figure 10 , and a cross-sectional view of a pinion shaped therein, in sub-view b) a partial close-up view of the area indicated by Z in sub-view a). DETAILED DESCRIPTION

[0058] For the sake of clarity, not every feature is provided with a reference sign in the drawings, but first only the features needed to illustrate the respective drawing are provided with a reference sign. This applies in particular to cases in which a plurality of features of the same type are shown, wherein in most cases only one or a few selected features are provided with a reference sign.

[0059] In Figure 1 , a bicycle is generally designated 10. The bicycle 10 comprises a frame 12, a front wheel 14, a rear wheel 16, handlebars 18 and a saddle 20. Even though the bicycle 10 shown here exemplarily is a racing bicycle, it is clear that the present application can equally be applied to other bicycle types, for example to a mountain bike.

[0060] Generally, a torque can be introduced into a front pinion or sprocket 27 of a toothed disc set 26 on the bicycle 10 by means of a pedal 22 and a crank 24. This torque is then transmitted by means of a closed, looped bicycle chain 30 to a pinion freewheel 32 on a rear wheel hub 17 of the bicycle 10.

[0061] The pinion freewheel 32 comprises a pinion set having a plurality of coaxially arranged, axially spaced and rotationally connected, different-diameter rear pinions, wherein the largest one in the example shown is a pinion 34 according to an embodiment of the present application.

[0062] The pinion 34 of the present application serves here as a final pinion 36 and is adapted to directly transmit the torque introduced by means of the bicycle chain 30 to the rear wheel hub 17 on the Figure 1 The drive that is not visible in Figure 9 is described in detail.

[0063] The rear pinion of the pinion freewheel 32 that engages the bicycle chain 30 can be selected in a known manner by means of a rear gear shift mechanism 37, and the corresponding front pinion or sprocket 27 is selected by means of a front derailleur 28. The rear gear shift mechanism 37 and the front derailleur 28 can each be controlled in a known manner, mechanically and / or electrically.

[0064] Figure 2 A top view is shown of the back side of the pinion 34, that is to say the side facing towards the rear wheel 16 in the installed state. Figure 3 A top view is shown of the front side of the pinion 34, Figure 4 A perspective view is shown.

[0065] The pinion 34 comprises an outer ring 40 having outer toothing 42 for engaging the bicycle chain 30, and an inner ring 44 having a central opening 46 that is coaxially arranged with respect to the outer ring 40 and rotationally connected to this outer ring, here integrally formed with this outer ring, with respect to a central axis M of the pinion 34.

[0066] The inner ring 44 and the outer ring 40 are constructed as flat ring disks in a first approximation and are connected by a plurality of connecting arms 43 which extend obliquely from the inner ring 44 towards the outside in a known manner.

[0067] On the pinion 34, integrally formed with the inner ring 44 and axially projecting to one side of the inner ring 44, there is a recess 46 which is axially open to the outside. Figure 2 The recess 46 is axially open to the observer in the axial direction.

[0068] The flange 48 has on its radially inner side an inner profile 47 which has a plurality of radially inwardly projecting protrusions 50. On the radially outer side of the flange 48 there is an outer profile 49 which has a plurality of radial recesses 52 which correspond to the number and arrangement of the radially protruding protrusions 50 of the inner profile 47.

[0069] Figures 4 to 6 It can be seen that the center plane E 42 of the outer toothing 42 is axially offset from the center plane E 40 of the inner ring 44. 44 In other words, the pinion 34 is recessed so that the outer toothing 42 can be positioned closer to the rear wheel 16.

[0070] In the example shown, the axial end face 48s of the circumferential flange 48 is arranged axially between the center plane E 44 of the inner ring 44 and the center plane E 42 of the outer toothing 42 or the center plane E 40 of the outer ring 40 (cf. Figure 6 ).

[0071] The shape of the flange 48, in particular the shape of the inner profile 47 and the outer profile 49, will be described in more detail below with reference to Figure 2a , Figure 4 , Figure 7 and Figure 8 .

[0072] In the present case, the inner profile 47 has for example nine protrusions 50 which are uniformly distributed over the circumference of the flange 48, and the outer profile 49 has correspondingly nine recesses 52 which are likewise so distributed. The exact shape of the inner profile 47 can differ from the shape of the outer profile 49 and is matched to the shape of the transmission applied.

[0073] The outer profile 49 preferably extends over approximately the entire axial length a 48 of the flange 48, and the inner profile 47 extends over approximately the axial length I, which is the sum of the axial length a 48 of the flange 48 and the axial extent or thickness d 44 of the inner ring 44 (cf. Figure 7 ).

[0074] the thickness d of the inner ring 44 for example 1.5 mm to 2 mm, preferably 1.6 mm to 1.8 mm. The axial length I mentioned above is here about 2.5 mm to 8 mm, preferably 3 mm to 7 mm, particularly preferably 3.3 mm to 6.5 mm.

[0075] Figure 2a , Figure 7 and Figure 8 The shape of the inner profile 47 and the outer profile 49 of the flange 48 is shown in different partial enlargements, which show that the protrusions 50 of the inner profile 47 are present with a clear asymmetry, whereas the corresponding recesses 52 of the outer profile 49 are generally mirror-symmetrically constructed with respect to the mirror plane S, which is present Figure 2a in the middle for the selected protrusion 50 and the corresponding recess 52.

[0076] Each protrusion 50 has a first tooth surface 50.1 (load tooth surface) arranged in front with respect to the selected direction of rotation D (here: positive direction of rotation) and a second tooth surface 50.2 (counter-tooth surface) arranged behind with respect to this preset direction of rotation D, which tooth surfaces are connected by a plateau section 54.

[0077] Between immediately adjacent protrusions 50 of the inner profile 47 there is a recessed area 56, which has two sections 56.1 and 56.2, wherein the first section 56.1 directly adjoins the first tooth surface 50.1 of the protrusion 50 and the second section 56.2 directly adjoins the second tooth surface 50.2 of the other adjacent protrusion 50. The first section 56.1 is here more set back than the second section 56.2, which results in the first tooth surface 50.1 having a greater length in the radial direction than the second tooth surface 50.2. The radial length r 50.2 of the second tooth surface can for example be 75% or less, preferably 66% or less (cf. Fig. 6) of the radial length r 50.1 of the first tooth surface. Figure 8

[0078] As will also be described in detail below, the flange 48 is manufactured in a forming process, in which the outer profile 49 is built up together with at least one preform of the inner profile 47 by applying suitable tools, which preform is shown in Figure 8 in broken lines and is also referred to as preliminary inner profile 51.

[0079] The final shape of the inner profile 47, in particular of the tooth surfaces 50.1, 50.2 of the protrusions 50 and of the recessed areas 56 of the inner profile 47, is preferably manufactured in a reworking step, for example by means of cutting or milling.

[0080] ​It should be noted that in the illustrated embodiment, the radial protrusions of the inner preform 51 are constructed as mirror symmetry in the preliminary approximation before reprocessing, and the asymmetry of the protrusions 50 of the final inner form 47 is only formed through reprocessing.

[0081] Before reprocessing, flange 48 has a substantially constant radial dimension r around its periphery. 48 The dimension is 1 to 2 mm, preferably 1.3 to 1.5 mm, and particularly preferably 1.4 mm. The radial depth r of the groove 52 corresponds to the radial length of the preform 51 of the inner shape. 52 For example, it can be 0.5mm to 0.7mm.

[0082] Figure 9 A partial cross-sectional perspective view of a pinion flywheel 32 according to a preferred embodiment of the invention is shown. The pinion flywheel 32 includes a pinion set 31 having a plurality of pinions arranged coaxially with respect to a central axis M, spaced apart axially and anti-rotatably connected, wherein the largest is Figures 1 to 8 The pinion 34 is shown. The remaining conventional pinions are labeled with reference numeral 33.

[0083] The pinion 31 is mounted on the transmission 60 and can be installed in a known manner on the bicycle 10. Figure 9 On the rear wheel hub shown in the image.

[0084] The transmission device 60 has a basic shape of a hollow cylinder, and has an annular protrusion 62 at the axial end, an external tooth section 64 that connects to the annular protrusion 62 in the axial direction, and a threaded section 66 that follows the external tooth section in the axial direction.

[0085] In order to transmit torque from the pinion 31 to the transmission device 60, the transmission device 60 engages with the protrusion 50 of the flange 48 of the largest pinion 34, which is constructed as the final pinion 36 in the embodiment of the present invention, in the region of the external tooth section 64.

[0086] The connector sleeve 70 can be screwed onto the threaded section 66. The connector sleeve 70, together with the annular protrusion 62, is used to axially fix the pinion 31.

[0087] The transmission device 60, the connector sleeve 70, and the pinion set 31, except for the final pinion 36, can be implemented in a conventional manner, such as as described in the disclosure EP 3461731A1.

[0088] In the case of using a conventional joint with an external tooth section extending axially over a relatively long length, multiple pinions designed according to the present invention can also be used as individual pinions or insert pinions. The circumferential flanges provided by the present invention for different pinions can be used as spacers, thus eliminating the need for separate spacer elements.

[0089] The following is combined with Figure 10 The greatly simplified flowchart and Figures 11 to 13 The schematic diagram illustrates an embodiment of the method for manufacturing the pinion of the present invention for a bicycle transmission. Figure 10 Optional steps in the flowchart are marked with dashed boxes.

[0090] First, in step i), a pinion blank 34' is stamped from sheet metal. The stamped pinion blank 34' includes at least one central pre-punched hole 46'. This pre-punched hole is preferably not round, but has multiple radially inwardly projecting protrusions 50' (see...). Figure 11 ).

[0091] In another step ii), the pinion blank 34' is further processed into a true pinion 34.

[0092] First, in step a), the small gear blank 34' is formed, wherein the punch 80 (see...) Figure 12 The gear blank 34' is pressed into the bottom mold 82 through the pre-punched hole 46', thereby forming an inner ring 44 with a central opening 46 and a surrounding flange 48 integrally formed with the inner ring 44 and protruding axially to one side of the inner ring. The flange 48 is formed by the material surrounding the central pre-punched hole 46' of the gear blank 34' and defines the central opening 46 of the final gear 34.

[0093] The cross-sectional shapes of the punch 80 and the die 82 are not circular in a plane perpendicular to the central axis M, but are chosen such that in step a), specifically in sub-step a1), an outer shape 49 with a plurality of radial grooves 52 and an inner shape 47 with a plurality of radially inwardly projecting radial protrusions 50 are formed on the flange 48, wherein the radial grooves 52 of the outer shape 49 correspond to the number and arrangement of the radial protrusions 50 of the inner shape 47.

[0094] Depending on the requirements, the axial dimension a of the flange 48 can be set more precisely in the subsequent forming step a2). 48 In this forming step, another punch 83 is used instead of the punch 82 applied in step a1), this other punch having another profile 85 for defining the end face 48s of the flange 48. This also allows for setting the flatness of the end face 48s. Figure 12 and Figure 13A comparison with the inner profile 47 shown in Fig. 1 shows that, as a result, the radius of curvature of the transition from the inner ring 44 to the radially inner side of the flange 48 can change.

[0095] Finally, the shape of the inner profile of the flange can optionally be reworked, in particular re-machined, so that the final shape of the inner profile 47 shown in solid lines is produced from the preform 51 shown in dashed lines. Figure 7

[0096] The method of the application enables a pinion with good torque transmission properties to be produced simply and advantageously.​

Claims

1. Pinion for a bicycle transmission, comprising: - an outer ring with external toothing for engaging with a bicycle chain, - an inner ring with a central opening arranged coaxially to the outer ring and rotationally connected to the outer ring, - a circumferential flange integrally formed with the inner ring and axially protruding to one side of the inner ring, the circumferential flange being constructed as a continuous flange, - wherein on the radially inner side of the circumferential flange an inner profile is provided, which has a plurality of radially inwardly protruding radial protrusions, characterized in that on the radially outer side of the circumferential flange an outer profile is provided, which has a plurality of radial recesses, which correspond to the number and arrangement of the radial protrusions of the inner profile, and in that each of the radial protrusions of the inner profile has a first tooth surface arranged in front with respect to a predetermined direction of rotation around the central axis of the pinion and a second tooth surface arranged behind with respect to the predetermined direction of rotation, wherein for at least one of the radial protrusions of the inner profile the first tooth surface and the second tooth surface are not mirror-symmetrical.

2. Pinion according to claim 1, characterized in that - the radial protrusions of the inner profile of the circumferential flange serve as transmission elements, which are suitable for directly transmitting torque from the pinion to a transmission device on a bicycle rear hub.

3. Pinion according to claim 1 or claim 2, characterized in that - for each of the radial protrusions of the inner profile the first tooth surface and the second tooth surface are not mirror-symmetrical.

4. Pinion according to claim 3, characterized in that - the first tooth surface of at least one of the radial protrusions of the inner profile has a greater radial length than the second tooth surface.

5. Pinion according to any one of claims 1 or 2, characterized in that - the axial end face of the circumferential flange is arranged axially between the central plane of the inner ring and the central plane of the outer toothing or the central plane of the outer ring for engaging with a bicycle chain.

6. Pinion freewheel for a bicycle transmission, comprising: - a pinion set with a plurality of coaxially arranged, axially spaced and rotationally connected pinions of different diameters, wherein one of the pinions is a final pinion, which is suitable for directly transmitting torque to a transmission device on a bicycle rear hub, - characterized in that the final pinion is a pinion according to any one of claims 1 to 5.

7. Bicycle transmission, comprising: - a transmission device and at least one pinion according to any one of claims 1 to 5 or / and a pinion freewheel according to claim 6.

8. Method for manufacturing a pinion for a bicycle transmission, comprising the following steps: i) punching out a pinion blank with a central pre-punching, ii) further processing the pinion blank to a pinion with a central opening, an inner ring and a circumferential flange integrally formed with the inner ring and axially protruding to one side of the inner ring, - wherein the step ii) at least comprises the following steps: - punching out the circumferential flange from the pinion blank, a) forming a pinion blank, wherein a punch is pressed through a pre-punching of the pinion blank into a bottom die to form a circumferential flange, characterized in that by the forming in step a) both an inner profile with a plurality of radially inwardly projecting radial protrusions is formed on the radially inner side of the circumferential flange and an outer profile with a plurality of radial recesses is formed on the radially outer side of the circumferential flange, the recesses corresponding to the number and arrangement of the radial protrusions of the inner profile.

9. The method according to claim 8, characterized in that in step i) the central pre-punching is constructed with a plurality of radially inwardly projecting protrusions, the protrusions corresponding to the number and arrangement of the radially inwardly projecting radial protrusions of the inner profile of the circumferential flange formed in step ii).

10. The method according to claim 8 or claim 9, characterized in that said step ii) further comprises the following step after step a): b) reworking the inner profile manufactured in the forming process of the circumferential flange.

11. The method according to claim 10, characterized in that said reworking is carried out by cutting or milling.

12. The method according to claim 10, characterized in that in said step b) for at least one of the protrusions of the inner profile the first tooth surface or / and the second tooth surface of the protrusion arranged in front with respect to the selected direction of rotation is reworked such that after the reworking the length of the first tooth surface in the radial direction is greater than the length of the second tooth surface in the radial direction.

13. The method according to claim 8 or claim 9, characterized in that said step a) further comprises the following step: a2) forming the pinion blank or the pinion such that a predetermined axial dimension of the circumferential flange is set.

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