Bicycle rear wheel hub

Abstract

The invention provides a bicycle rear wheel hub which comprises a middle shaft, a hub shell and a tower footing, the hub shell and the tower footing are rotatably arranged on the middle shaft, the middle shaft is further provided with a rotary driving ratchet wheel and a rotary clutch ratchet wheel, a first bearing is arranged between the hub shell and the middle shaft, a first spline is arranged on the periphery of the driving ratchet wheel, and a second spline is arranged on the periphery of the clutch ratchet wheel. A first spline groove is formed in the inner circumferential face of a center hole of the hub shell. Or, a first spline groove is formed in the periphery of the driving ratchet wheel, a first spline is arranged on the inner circumferential face of the middle hole of the hub shell, and the first spline penetrates into the first spline groove; the end face, deviating from the clutch ratchet, of the driving ratchet is provided with a containing groove matched with the first bearing in size. Through spline fit between the driving ratchet wheel and the hub shell, the concentricity problem caused by traditional threaded connection is avoided, the containing groove is formed in the end face of the driving ratchet wheel, the first bearing can be partially or completely embedded, the bearing installation position deviates towards the tower footing side (namely, the bearing installation position is far away from the center of a center shaft), and therefore stress is dispersed, and concentrated abrasion of the first bearing is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of bicycle hubs, in particular to a bicycle rear wheel hub. Background Art

[0002] A bicycle wheel typically includes a bicycle hub assembly. The bicycle hub assembly is located at the center of the bicycle wheel. A conventional bicycle hub assembly includes a hub axle (bottom bracket), a hub body, a bearing unit, a ratchet body, and a locking member. The hub axle is mounted to the bicycle frame. The hub body is rotatably supported about the hub axle via the bearing unit. The bearing unit is disposed between the hub axle and the hub body. The ratchet is configured to synchronize the rotation of the hub body and the freewheel body during pedaling.

[0003] In order to install the sprocket and the freehub, the existing hub has the drive ratchet and other components installed near the center of the hub axle. As a result, the bearing installed between the center hole of the hub and the end face of the drive ratchet is closer to the middle of the hub axle, causing the bearing installed at this position to become the main load-bearing bearing. During use, it wears more than the bearings at other positions, thereby shortening the overall life of the hub, as shown in the patent document with the announcement number CN108437699B. To address this issue, a solution has emerged: a small groove has been dug into the drive ratchet to accommodate the bearing, allowing the bearing to be positioned more centrally than in solutions with a further-away arrangement. As shown in patent publication CN216467162U, the hub housing and drive ratchet are connected via threaded locking. However, this method makes it extremely difficult to ensure the concentricity of the bearings on both sides of the hub. Furthermore, after prolonged use, if the bearing becomes damaged, it becomes difficult to remove the threaded drive ratchet (because the locking direction of the thread is the same as the driving direction). Furthermore, since the thread is always angled, it is difficult to ensure that the bearing is completely aligned with the horizontal plane after final installation. To ensure smooth contact between the bearing, the hub housing, and the bottom bracket (keeping it as coaxial as possible with the bottom bracket), the depth of the groove is limited to ensure that the majority of the bearing surface contacts the hub housing (to compensate for angular deviation caused by the threaded drive ratchet). Consequently, the distance the bearing can be offset from the center is also limited, making it less effective in mitigating bearing wear. Otherwise, the angle between the bearing axis and the bottom bracket axis will increase, which in turn increases wear. Summary of the Invention

[0004] To solve the above problems, an object of the present invention is to provide a bicycle rear wheel hub.

[0005] The present invention is implemented by the following method: a bicycle rear wheel hub, comprising a central shaft, a hub shell and a freewheel base, the hub shell and the freewheel base being rotatably arranged on the central shaft, the central shaft further being provided with a rotatable driving ratchet and a clutch ratchet, the driving ratchet and the clutch ratchet having ratchet teeth mating with each other on opposing surfaces, a first bearing being provided between the hub shell and the central shaft, a first bearing mounting section being provided on a side of a central hole of the hub shell close to the freewheel base, the outer periphery of the driving ratchet being provided with a first spline, and the inner peripheral surface of the first bearing mounting section of the central hole of the hub shell being provided with a first spline groove; or, the outer periphery of the driving ratchet being provided with a first spline groove, the inner peripheral surface of the first bearing mounting section of the central hole of the hub shell being provided with a first spline, the first spline being inserted into the first spline groove; an end surface of the driving ratchet facing away from the clutch ratchet being provided with a receiving groove matching the size of the first bearing, the first bearing being partially or completely located in the receiving groove; the clutch ratchet being circumferentially limitedly connected to the freewheel base. Preferably, the first spline is composed of a plurality of key bodies, which are arranged at intervals around the outer peripheral surface of the driving ratchet, and the corresponding first spline groove is also composed of a plurality of groove bodies arranged at annular intervals on the inner peripheral surface of the first bearing mounting section.

[0006] Preferably, the key bodies all protrude toward one end away from the clutch ratchet, and the space formed by the protruding parts of all the key bodies constitutes the accommodating groove. The outer peripheral surface of the first bearing contacts the inner peripheral surface of the bearing mounting section, and at the same time contacts the inner peripheral surfaces of multiple key bodies.

[0007] Preferably, the first spline is composed of a plurality of key bodies, and the plurality of key bodies are arranged at intervals around the inner circumference of the first bearing mounting section. The corresponding first spline groove is also composed of a plurality of groove bodies arranged at annular intervals on the outer circumference of the driving ratchet.

[0008] Preferably, the circumferential surface of the accommodating groove is respectively connected with the inner side surfaces of the plurality of groove bodies, and there is a distance between the end surface of the groove body adjacent to the clutch ratchet and the end surface of the driving ratchet facing the clutch ratchet, and the outer circumferential surface of the first bearing contacts the inner circumferential surface of the bearing mounting section and the inner circumferential surface of the key body, and at the same time contacts the inner circumferential surface of the accommodating groove.

[0009] Preferably, the outer circumference of the clutch ratchet is provided with a second spline, and the inner circumference of the inner circumference of the tower base close to the hub shell is provided with a second spline groove, and the second spline penetrates into the second spline groove.

[0010] Preferably, a spring is further provided in the tower base, one end of the spring presses against the end face of the clutch ratchet facing away from the driving ratchet, and the other end of the spring is connected to the axial limit of the tower base for pushing the clutch ratchet toward the driving ratchet.

[0011] Preferably, an accommodating groove is provided on the end surface of the clutch ratchet facing away from the driving ratchet, and one end of the spring extends into the accommodating groove and abuts against the inner end surface of the accommodating groove.

[0012] Preferably, a plurality of second bearings are provided on the middle shaft and between the tower base, a bearing spacer is provided between adjacent second bearings on the middle shaft, and a bearing spacer is also provided between the second bearing on the side of the middle shaft close to the hub shell and the first bearing; a stop ring is provided on the middle shaft at one end of the driving ratchet located on the first bearing away from the tower base to abut against the inner ring of the first bearing, and the first bearing mounting section of the hub shell abuts against the outer ring of the first bearing; the other end of the spring abuts against the end face of the second bearing in the tower base close to the side of the hub shell; a sealing ring metal ring and a sealing ring rubber are connected between the tower base and the opposite end faces of the hub shell; end covers are provided at both ends of the middle shaft, the end cover at one end abuts against the side of the tower base away from the hub shell, and the end cover at the other end abuts against the side of the hub shell away from the tower base.

[0013] Preferably, a convex ring surrounding the central axis is provided on the end face of the hub shell facing away from the tower base, and a third spline is provided on the outer peripheral surface of the convex ring for circumferential limiting connection to the disc brake.

[0014] The beneficial effects of the present invention are as follows: The present invention provides a bicycle rear wheel hub. Compared with the prior art, the present invention has at least the following technical effects: 1. By using a spline fit (first spline and first spline groove) between the drive ratchet and the hub shell, the concentricity problem caused by traditional threaded connections is avoided. The axial guidance of the spline ensures the coaxiality of the bearing during installation, and the receiving groove can be machined deeper. The directly machined spline base can achieve more precise control of precision and is more practical and effective in extending the life of the bearing. The receiving groove is provided on the end face of the drive ratchet, so that the first bearing can be partially or fully embedded, offsetting the bearing installation position toward the freehub base (i.e., away from the center of the bottom bracket), thereby distributing the force and reducing concentrated wear of the first bearing. 2. The fit of multiple spaced key bodies and groove bodies improves the uniform force-bearing capacity of the spline connection and reduces the risk of local stress concentration. The torque transmission stability between the hub shell and the drive ratchet is enhanced while maintaining lightweight. 3. The circumference of the receiving groove is formed by multiple key bodies surrounding it, or the inner side of the key groove is connected to the circumference of the receiving groove. This ensures the contact area between the outer circumference of the bearing and the hub shell, while further increasing the depth of the receiving groove so that the first bearing can be installed more in the drive ratchet, further increasing the distance the first bearing deviates from the center of the center shaft, further reducing the stress. In addition, the semi-open spline ring formed by the dispersed and spaced key grooves and key bodies can form a larger thickness and width of key grooves and key bodies during processing, increasing the contact surface between the drive ratchet and the hub shell during driving, which helps to improve driving efficiency. Therefore, whether from the perspective of processing difficulty, product precision, or user experience, the semi-enclosed spline connection is superior to existing threaded connections on the market in terms of improving the durability and smoothness of the hub. 4. The spline connection between the clutch ratchet and the freehub replaces the traditional threaded or pin connection method, achieving quick disassembly and assembly while ensuring the immediate responsiveness of power transmission. 5. Continuously apply axial thrust through the spring to ensure that the ratchet teeth of the clutch ratchet and the drive ratchet are tightly engaged to prevent slipping when pedaling. 6. Embedding the end of the spring into the receiving groove of the clutch ratchet can, on the one hand, avoid spring deflection, improve the consistency of thrust direction, and enhance system reliability. On the other hand, it also helps to reduce the axial space occupied by the freehub, clutch ratchet, and spring on the bottom bracket, which can further help the first bearing move away from the middle position of the bottom bracket, further reducing the force on the first bearing. 7. Adjacent bearings are separated by spacers to precisely control the bearing spacing and optimize load distribution; sealing ring combination: metal rings provide rigid support, and rubber rings achieve elastic sealing, taking into account dust and water resistance and durability. 8. Through the dedicated spline interface at the end of the hub shell, the disc brake rotor can be quickly installed and precisely aligned. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is an exploded view of a bicycle rear wheel hub according to the present invention.

[0016] Figure 2 It is a separate cross-sectional view of a component of a bicycle rear wheel hub according to the present invention.

[0017] Figure 3 The present invention is a schematic diagram of the cross-sectional structure of a bicycle rear wheel hub.

[0018] Figure 4 It is a schematic diagram of the separation of the hub shell, the first bearing, and the driving ratchet assembly of the present invention.

[0019] Figure 5 It is a schematic cross-sectional view of the hub housing, the first bearing, and the driving ratchet after being assembled according to the present invention.

[0020] Figure 6 It is an assembly diagram of the driving ratchet and the first bearing.

[0021] Figure 7 The utility model is a structural schematic diagram of a bicycle rear wheel hub which can be equipped with a disc brake disc according to the present invention.

[0022] Figure 8 The present invention is a cross-sectional view of a bicycle rear wheel hub that can be equipped with a disc brake disc.

[0023] Explanation of the accompanying reference numerals: 1. bottom bracket; 2. hub shell; 21. first spline groove; 22. third spline; 3. freehub base; 31. second spline groove; 4. driving ratchet; 41. first spline; 42. receiving groove; 5. clutch ratchet; 51. second spline; 52. receiving groove; 6. first bearing; 7. spring; 8. second bearing; 9. bearing spacer; 10. sealing ring metal ring; 11. sealing ring rubber; 12. end cover. DETAILED DESCRIPTION The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0024] See also Figures 1 to 8A bicycle rear wheel hub can be used for V brakes or disc brakes, including a middle shaft 1, a hub shell 2 and a freehub 3. The hub shell 2 and the freehub 3 are rotatably arranged on the middle shaft 1. The middle shaft 1 is also provided with a rotating driving ratchet 4 and a clutch ratchet 5. The driving ratchet 4 and the clutch ratchet 5 are provided with ratchet teeth that cooperate with each other on the opposite surfaces. A first bearing 6 is provided between the hub shell 2 and the middle shaft 1. A first bearing mounting section is provided on the side of the center hole of the hub shell 2 close to the freehub 3. A first spline 41 is provided on the outer periphery of the driving ratchet 4. The inner circumference of the first bearing mounting section of the central hole of the body 2 is provided with a first spline groove 21; or, the outer circumference of the driving ratchet 4 is provided with a first spline groove 21, and the inner circumference of the first bearing mounting section of the central hole of the hub shell 2 is provided with a first spline 41, and the first spline 41 penetrates into the first spline groove 21; the end face of the driving ratchet 4 facing away from the clutch ratchet 5 is provided with a receiving groove 42 that matches the size of the first bearing 6, and the first bearing 6 is partially or completely located in the receiving groove 42; the clutch ratchet 5 is connected to the circumferential limit of the tower base 3. The splined fit between the drive ratchet 4 and the hub housing 2 (first spline 41 and first spline groove 21) avoids the concentricity issues associated with traditional threaded connections. The axial guidance of the spline ensures coaxiality during bearing installation. The directly machined spline base provides greater precision, effectively extending bearing life. A receiving groove 42 is provided on the end face of the drive ratchet 4 to allow partial or full internal insertion of the first bearing 6, shifting the bearing installation position toward the freehub base 3 (i.e., away from the center of the bottom bracket 1). This disperses the load and reduces concentrated wear on the first bearing 6. This allows the depth of the receiving groove 42 to be increased from 3mm to at least 8mm, significantly alleviating the concentrated load on the first bearing 6.

[0025] See also Figures 1 to 8 Preferably, the inner end face of the accommodating groove 42 also has a secondary recessed groove, which gives way to the inner ring end face of the first bearing 6 so that the accommodating groove 42 only contacts the outer ring of the first bearing 6.

[0026] See also Figures 1 to 8 Preferably, the first spline 41 is composed of multiple key bodies, which are spaced and arranged around the outer circumference of the driving ratchet 4. Correspondingly, the first spline groove 21 is similarly composed of multiple groove bodies, which are annularly spaced and arranged around the inner circumference of the first bearing mounting section. The multiple spaced key bodies cooperate with the groove bodies to improve the uniform force-bearing capacity of the spline connection, reduce the risk of localized stress concentration, and enhance the torque transmission stability between the hub shell 2 and the driving ratchet 4, while maintaining lightweight.

[0027] See also Figures 1 to 8Preferably, the key bodies all protrude toward the end away from the clutch ratchet 5, and the space formed by the protruding parts of all the key bodies constitutes the accommodating groove 42. The outer peripheral surface of the first bearing 6 contacts the inner peripheral surface of the bearing mounting section and contacts the inner peripheral surfaces of multiple key bodies. The circumference of the accommodating groove 42 is formed by multiple key bodies surrounding it, which can ensure the contact area between the outer peripheral surface of the bearing and the hub shell 2. At the same time, it further increases the depth of the accommodating groove 42 so that the first bearing 6 can be installed more in the driving ratchet 4, so that the distance from the center of the central axis 1 of the first bearing 6 is further increased, further reducing the stress. In addition, the semi-open spline ring formed by the dispersed and spaced keyways and key bodies can form keyways and key bodies with larger thickness and width during processing, increasing the contact surface between the driving ratchet 4 and the hub shell 2 during driving, which helps to improve driving efficiency. Therefore, whether from the perspective of processing difficulty, product precision, or user experience, the spline connection of the semi-enclosed structure is superior to the existing threaded connection methods on the market in improving the durability and smoothness of the hub.

[0028] See also Figures 1 to 8 Preferably, the first spline 41 is composed of multiple key bodies, which are spaced and arranged around the inner circumference of the first bearing mounting section. Correspondingly, the first spline groove 21 is also composed of multiple groove bodies, which are annularly spaced and arranged around the outer circumference of the driving ratchet 4. The multiple spaced key bodies cooperate with the groove bodies to improve the uniform force bearing capacity of the spline connection, reduce the risk of local stress concentration, and enhance the torque transmission stability between the hub shell 2 and the driving ratchet 4, while maintaining lightweight.

[0029] See also Figures 1 to 8 Preferably, the circumferential surface of the accommodating groove 42 is respectively connected to the inner side surfaces of the plurality of groove bodies, and there is a distance between the end surface of the groove body adjacent to the clutch ratchet 5 and the end surface of the driving ratchet 4 facing the clutch ratchet 5, and the outer circumferential surface of the first bearing 6 contacts the inner circumferential surface of the bearing mounting section and the inner circumferential surface of the key body, and at the same time contacts the inner circumferential surface of the accommodating groove 42. The inner side of the keyway is connected to the circumference of the receiving groove 42, which can ensure the contact area between the outer circumference of the bearing and the hub shell 2. At the same time, the depth of the receiving groove 42 is further increased, allowing the first bearing 6 to be installed more in the driving ratchet 4, further increasing the distance from the center of the central axis 1 of the first bearing 6, and further reducing the stress. In addition, the semi-open spline ring formed by the dispersed and spaced keyways and key bodies can form keyways and key bodies with larger thickness and width during processing, increasing the contact surface between the driving ratchet 4 and the hub shell 2 during driving, which helps to improve driving efficiency. Therefore, whether from the perspective of processing difficulty, product precision, or user experience, the semi-enclosed spline connection is superior to existing threaded connections on the market in improving the durability and smoothness of the hub. The groove body runs through both ends of the driving ratchet 4.

[0030] See also Figures 1 to 3 、 Figure 8 Preferably, the outer circumference of the clutch ratchet 5 is provided with a second spline 51, and the inner circumference of the freehub base 3, adjacent to the hub housing 2, is provided with a second spline groove 31, into which the second spline 51 penetrates. The splined connection between the clutch ratchet 5 and the freehub base 3 replaces traditional threaded or pinned connections, enabling quick assembly and disassembly while ensuring immediate responsiveness in power transmission. This also better meets the coaxiality requirements between the clutch ratchet and the bottom bracket, reducing wear on the clutch ratchet 5 and the drive ratchet 4.

[0031] See also Figures 1 to 3 、 Figure 8 Preferably, a spring 7 is further provided in the freewheel base 3. One end of the spring 7 abuts against the end face of the clutch ratchet 5 facing away from the driving ratchet 4, and the other end of the spring 7 is connected to the freewheel base 3 for axial positioning, thereby pushing the clutch ratchet 5 toward the driving ratchet 4. The spring 7 continuously applies axial thrust, ensuring that the ratchet teeth of the clutch ratchet 5 and the driving ratchet 4 are tightly engaged, preventing slipping when pedaling.

[0032] See also Figures 1 to 3 、 Figure 8 Preferably, a receiving groove 52 is provided on the end surface of the clutch ratchet 5 facing away from the driving ratchet 4. One end of the spring 7 extends into the receiving groove 52 and abuts against the inner end surface of the receiving groove 52. Embedding the end of the spring 7 in the receiving groove 52 of the clutch ratchet 5 can, on the one hand, prevent deflection of the spring 7, improve the consistency of the thrust direction, and enhance system reliability. On the other hand, it also helps to reduce the axial space occupied by the freehub 3, clutch ratchet 5, and spring 7 on the bottom shaft 1, further helping the first bearing 6 to move away from the center position of the bottom shaft 1, further reducing the force on the first bearing 6.

[0033] See also Figures 1 to 3 、 Figure 8, Preferably, a plurality of second bearings 8 are provided between the middle shaft 1 and the freehub 3, and a bearing spacer 9 is provided between adjacent second bearings 8 on the middle shaft 1, and a bearing spacer 9 is also provided between the second bearing 8 on the middle shaft 1 close to the side of the hub shell 2 and the first bearing 6; a stop ring is provided on the middle shaft 1 at one end of the driving ratchet 4 located away from the freehub 3 at the first bearing 6 to abut against the inner ring of the first bearing 6, and the first bearing mounting section of the hub shell 2 abuts against the outer ring of the first bearing 6; the other end of the spring 7 abuts against the end face of the second bearing 8 in the freehub 3 close to the side of the hub shell 2; a sealing ring metal ring 10 and a sealing ring rubber 11 are connected between the opposite end faces of the freehub 3 and the hub shell 2; end covers 12 are provided at both ends of the middle shaft 1, the end cover 12 at one end abuts against the side of the freehub 3 away from the hub shell 2, and the end cover 12 at the other end abuts against the side of the hub shell 2 away from the freehub 3. Adjacent bearings are separated by spacers to precisely control bearing spacing and optimize load distribution. The sealing ring combination: the metal ring provides rigid support, and the rubber ring achieves elastic sealing, taking into account dust and water resistance and durability.

[0034] See also Figure 7 、 Figure 8 Preferably, the end face of the hub housing 2 facing away from the freehub base 3 is provided with a raised ring surrounding the center axle 1. A third spline 22 is provided on the outer circumference of the raised ring for circumferentially limiting connection to the disc brake. The dedicated spline interface at the end of the hub housing 2 enables quick installation and precise alignment of the disc brake rotor.

[0035] The present invention has the following working principle: The driving ratchet 4 and the center hole of the hub shell 2 are connected by the first spline 41 and the first spline groove, which avoids the concentricity problem caused by the traditional threaded connection. Therefore, the first bearing 6 will not produce an angular deviation from the axial direction due to being installed in the receiving groove 42, and the depth of the receiving groove 42 can be safely increased to facilitate disassembly and maintenance; the driving ratchet 4 is provided with a receiving groove 42 surrounded by a plurality of key bodies arranged at intervals, forming a semi-enclosed structure for the first bearing 6, so that the part of the first bearing 6 inserted into the receiving groove 42 can still contact the inner circumference of the center hole of the hub shell 2 (ensuring the correction effect of the center hole on the installation deviation of the first bearing 6), Increasing the depth of the accommodating groove 42 in one step allows the first bearing 6 to be installed more in the driving ratchet 4, further increasing the distance the first bearing 6 deviates from the center of the central axis 1, further reducing the force, and distributing it to the remaining second bearings 8, which can increase the service life of the entire hub; the semi-open spline ring formed by the dispersed and spaced keyways and keyways can form keyways and keyways with larger thickness and width during processing, increasing the contact surface between the driving ratchet 4 and the hub shell 2 during driving (the area of each key body facing the rotation direction is significantly increased when pushing, and the area of the pushed surface of the slot body is also significantly increased), which helps to improve the driving efficiency.

[0036] During driving, the driving force generated by the pedals is transmitted to the tower base 3 through the chain, chainring, etc., and the tower base 3 is then transmitted to the clutch ratchet 5 through the second spline 51 and the second spline groove 31. The clutch ratchet 5 is then transmitted to the drive ratchet 4 through the ratchet teeth (the clutch ratchet 5 is always in contact with the drive ratchet 4 by the axial thrust of the spring 7), and the drive ratchet 4 is then transmitted to the hub shell 2 through the first spline 41 and the first spline groove 21. When the pedals do not provide driving force and generate resistance, the tower base 3 will provide a reverse rotation force to the clutch ratchet 5, and the ratchet teeth on the drive ratchet 4 cannot provide a reverse circumferential limit, so that the drive ratchet 4 and the clutch ratchet 5 will rotate relative to each other, and the ratchet teeth on the drive ratchet 4 push the ratchet teeth on the clutch ratchet 5 so that the clutch ratchet 5 overcomes the axial force of the spring 7 and moves away from the drive ratchet 4, thereby realizing power cut-off.

[0037] Several points should be explained: First, in the description of this application, it should be noted that, unless otherwise specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, which can be mechanical connection or electrical connection, or internal communication between two components, or direct connection. "Up", "down", "left", "right", etc. are only used to indicate relative position relationships. When the absolute position of the object being described changes, the relative position relationship may change.

[0038] Secondly: In the drawings of the embodiments disclosed in the present invention, only the structures related to the embodiments disclosed in the present invention are involved. Other structures can refer to the general design. In the absence of conflict, the same embodiment and different embodiments of the present invention can be combined with each other.

[0039] Finally, the above description is only a preferred embodiment of the present invention. The protection scope of the present invention is not limited to the above embodiment. All technical solutions under the concept of the present invention belong to the protection scope of the present invention.

[0040] It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications without departing from the principle of the present invention should also be considered as the scope of protection of the present invention.

Claims

1. A bicycle rear wheel hub, comprising a bottom bracket, a hub housing, and a freewheel base, wherein the hub housing and freewheel base are rotatably mounted on the bottom bracket, the bottom bracket further comprising a rotatable drive ratchet and a clutch ratchet, wherein opposing surfaces of the drive ratchet and the clutch ratchet are provided with mating ratchet teeth, and a first bearing is disposed between the hub housing and the bottom bracket, characterized in that: A first bearing mounting section is provided on the side of the center hole of the hub shell close to the tower base, a first spline is provided on the outer periphery of the driving ratchet, and a first spline groove is provided on the inner peripheral surface of the first bearing mounting section of the center hole of the hub shell; or, a first spline groove is provided on the outer periphery of the driving ratchet, a first spline is provided on the inner peripheral surface of the first bearing mounting section of the center hole of the hub shell, and the first spline penetrates into the first spline groove; an end face of the driving ratchet facing away from the clutch ratchet is provided with a receiving groove matching the size of the first bearing, and the first bearing is partially or completely located in the receiving groove; the clutch ratchet is connected to the tower base in a circumferential limiting manner.

2. The bicycle rear wheel hub according to claim 1, characterized in that: The first spline is composed of a plurality of key bodies, which are arranged at intervals around the outer peripheral surface of the driving ratchet. The corresponding first spline groove is also composed of a plurality of groove bodies arranged at annular intervals on the inner peripheral surface of the first bearing mounting section.

3. The bicycle rear wheel hub according to claim 2, characterized in that: The key bodies all protrude toward one end away from the clutch ratchet, and the space formed by the protruding parts of all the key bodies constitutes the accommodating groove. The outer peripheral surface of the first bearing contacts the inner peripheral surface of the bearing mounting section and contacts the inner peripheral surfaces of multiple key bodies at the same time.

4. The bicycle rear wheel hub according to claim 1, characterized in that: The first spline is composed of a plurality of key bodies, which are arranged at intervals around the inner circumference of the first bearing mounting section. The corresponding first spline groove is also composed of a plurality of groove bodies which are arranged at intervals around the outer circumference of the driving ratchet.

5. The bicycle rear wheel hub according to claim 4, characterized in that: The circumferential surface of the accommodating groove is respectively connected to the inner side surfaces of the multiple groove bodies, and there is a distance between the end surface of the groove body adjacent to the clutch ratchet and the end surface of the driving ratchet facing the clutch ratchet. The outer circumferential surface of the first bearing contacts the inner circumferential surface of the bearing mounting section and the inner circumferential surface of the key body, and at the same time contacts the inner circumferential surface of the accommodating groove.

6. The bicycle rear wheel hub according to claim 1, characterized in that: A second spline is provided on the outer circumference of the clutch ratchet, and a second spline groove is provided on the inner circumference of a section of the inner circumference of the freehub close to the hub shell, and the second spline penetrates into the second spline groove.

7. The bicycle rear wheel hub according to claim 1, characterized in that: A spring is further provided in the tower base, one end of the spring presses against the end surface of the clutch ratchet facing away from the driving ratchet, and the other end of the spring is connected to the axial limit of the tower base for pushing the clutch ratchet toward the driving ratchet.

8. The bicycle rear wheel hub according to claim 7, characterized in that: An accommodating groove is provided on the end surface of the clutch ratchet wheel facing away from the driving ratchet wheel, and one end of the spring extends into the accommodating groove and abuts against the inner end surface of the accommodating groove.

9. The bicycle rear wheel hub according to claim 7, characterized in that: A plurality of second bearings are also provided on the middle shaft between the tower base, and bearing spacers are provided between adjacent second bearings on the middle shaft, and a bearing spacer is also provided between the second bearing on the side of the middle shaft close to the hub shell and the first bearing; a stop ring is provided on the middle shaft at one end of the driving ratchet located on the first bearing away from the tower base to abut against the inner ring of the first bearing, and the first bearing mounting section of the hub shell abuts against the outer ring of the first bearing; the other end of the spring abuts against the end face of the second bearing in the tower base close to the side of the hub shell; a sealing ring metal ring and a sealing ring rubber are connected between the tower base and the opposite end faces of the hub shell; end covers are provided at both ends of the middle shaft, the end cover at one end abuts against the side of the tower base away from the hub shell, and the end cover at the other end abuts against the side of the hub shell away from the tower base.

10. The bicycle rear wheel hub according to claim 1, characterized in that: A convex ring surrounding the central axis is provided on the end face of the hub shell on one side away from the tower base, and a third spline is provided on the outer peripheral surface of the convex ring for circumferential limiting connection to the disc brake.

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