Variable speed bicycle transmission system with emergency fixed gear ratio mode

Abstract

The utility model discloses a variable speed bicycle transmission system with emergency fixed tooth ratio mode, it is in solving the technical problem of traditional variable speed bicycle's transmission failure or chain breakage after difficult quick repair in field environment. The core technical features of the transmission system are: in the multiple toothed discs of rear flywheel group, a "straight chain line toothed disc" is designed in advance, the rotation plane of the toothed disc and the rotation plane of the front toothed disc are in the same plane or approximately the same plane, the straight chain line toothed disc surface is provided with eye -catching color mark, and the user is convenient for quick identification. The vehicle is equipped with small tool group such as chain cutter, quick connecting buckle and the like, and length reference rope or pre -cut spare chain. When the transmission system fails, the user finds the straight chain line toothed disc according to the color mark, uses the tool to cut the chain to the marked length, and installs the chain between the front toothed disc and the straight chain line toothed disc through the quick connecting buckle, and the whole process can be completed in minutes without professional knowledge.

Description

Technical Field

[0001] This utility model relates to the field of bicycle transmission technology, and in particular to a bicycle transmission system with an emergency fixed gear ratio mode. It is applicable to various bicycles that use chain drive and are equipped with a gear shifting device, including but not limited to mechanically shifted bicycles, electric-assisted shifted bicycles, electronically shifted bicycles, and other bicycles and their derivative models with multi-gear transmission functions. Background Technology

[0002] As a widely used means of transportation and exercise, the reliability of the bicycle's transmission system directly affects the user experience and safety. Modern bicycles generally employ a chain drive combined with a gear system. Through the cooperation of the front sprocket, rear freewheel, chain, and derailleur, multiple gears are achieved to adapt to different road conditions and riding needs. The gear system drives the chain through a chain guide mechanism to switch between multiple sprockets on the rear freewheel, changing the gear ratio and thus adjusting riding speed and effort.

[0003] In transmission system design, chain alignment is a crucial geometric parameter, referring to the alignment between the rotational plane of the front sprocket and the rotational plane of a specific sprocket in the rear sprocket assembly. When the front sprocket and a particular sprocket in the rear sprocket are on the same or nearly the same plane, the lateral chain offset is minimized, resulting in the highest transmission efficiency. This sprocket is typically located in the middle of the rear sprocket assembly, where the chain path is straightest and wear is minimal.

[0004] Several solutions exist for improving bicycle drivetrain systems. For example, Chinese utility model patent CN220054060U discloses a power-assisted bicycle drivetrain system. This system increases the damping between the outer gear and the gear shaft by incorporating a damping plate in the third drive shaft, thereby preventing circumferential and axial wobble of the outer gear, achieving vibration and noise reduction, and improving the NVH (noise, vibration, and harshness) performance of the power-assisted bicycle. This technical solution primarily addresses performance optimization under normal use conditions.

[0005] However, existing bicycle drivetrain systems have the following shortcomings: During rides in the wild or far from repair shops, the gear system may malfunction for various reasons, such as damaged derailleurs, broken shift cables, chain guide failure, or the chain breaking due to impact from branches, rocks, or other objects. Once these malfunctions occur, the bicycle's shifting function will be completely lost, often forcing the rider to push the bike or seek external assistance, severely impacting the completion of their ride and potentially posing safety hazards in some situations. This problem is particularly prominent in scenarios requiring high reliability, such as off-road riding and long-distance touring.

[0006] While cyclists can carry spare chains and repair tools, in emergency situations, ordinary users often lack the expertise to determine which chainring to use for a fixed gear ratio and the required chain length. This leads to a complex and time-consuming repair process, and may even result in repair failure due to improper operation. Current technology lacks a simple, intuitive, and easy-to-use emergency transmission solution that allows non-professionals to quickly restore the basic riding function of a bicycle after a gear system failure.

[0007] Therefore, it is necessary to provide a new technical solution that, while maintaining normal gear shifting function, can quickly switch to a fixed gear ratio mode through simple operation when the gear shifting system fails, allowing the bicycle to continue to be used, thereby improving the reliability and practicality of the bicycle in various usage scenarios. Summary of the Invention

[0008] The purpose of this invention is to provide a transmission system for a bicycle with an emergency fixed gear ratio mode, in order to solve the technical problem that existing bicycles are unable to quickly restore transmission function when the transmission system malfunctions in the wild or in emergency situations, which can lead to riders getting stuck.

[0009] To achieve the above objectives, the present invention adopts the following technical solution: A bicycle drivetrain with an emergency fixed gear ratio mode includes a front sprocket, a rear cassette, a chain, and a derailleur. The rear cassette is composed of multiple sprockets with different numbers of teeth mounted coaxially. The plane of rotation of the front sprocket and the plane of rotation of a specific sprocket in the rear cassette lie in the same or approximately the same plane; this specific sprocket is defined as a chain-link sprocket. The visible surface of the chain-link sprocket is color-coded for quick identification. The number of chain links required in emergency mode is marked on the frame. The system is equipped with a chain quick-handling tool kit, including a chain cutter and quick-connect buckles. When the drivetrain malfunctions, the chain is cut to a predetermined length and installed between the front sprocket and the chain-link sprocket to form a fixed gear ratio drive. The chain length is pre-calculated based on the number of teeth on the front sprocket, the number of teeth on the chain-link sprocket, and the center distance between the front and rear sprockets, allowing the installed chain to naturally generate appropriate tension for stable transmission.

[0010] Preferably, the color marking is at least one of a ring-shaped color band, a color block, or a reflective material, and preferably uses high-contrast or fluorescent colors to improve visibility in various environments.

[0011] Preferably, the system is equipped with a length standard reference rope, the length of which corresponds to the chain length required in emergency mode. During use, the reference rope is compared to the chain on a flat surface to determine the chain cutting length. Furthermore, the reference rope uses the same or a similar color as the color markings on the straight chain sprocket and is securely stored in a convenient location on the frame for easy matching and retrieval by the user.

[0012] Preferably, the system is equipped with a spare chain pre-cut to the accurate length and fitted with a quick-connect buckle, which can directly replace the damaged original chain, further simplifying the emergency operation process.

[0013] Preferably, the frame is provided with color markings or text descriptions corresponding to the color markings of the linear chain sprockets, indicating the information of the linear chain sprockets required for emergency mode and the corresponding number of chain links, forming a complete visual recognition system.

[0014] Preferably, a second emergency sprocket is provided in the rear freewheel assembly. The chain offset angle between the second emergency sprocket and the front sprocket is within an acceptable range. Different color markings are provided on the straight-chain sprocket and the second emergency sprocket, allowing the user to select different emergency gear ratios according to road conditions. Furthermore, two reference ropes of different lengths or two pre-cut spare chains are provided, corresponding to the two emergency modes respectively. Each reference rope or spare chain uses the same color marking as its corresponding sprocket for easy identification and use.

[0015] Preferably, the color markings on the chainring sprocket are made of luminescent or reflective material, making them clearly visible at night or in low-light conditions by absorbing light and then emitting it or reflecting it, ensuring operability under various lighting conditions. Furthermore, miniature reference labels corresponding to the color markings on the chainring sprocket are placed in prominent positions on the handlebars or frame, and the reference ropes are also made of luminescent or reflective material, forming a comprehensive nighttime visible marking system.

[0016] The beneficial effects of this utility model are as follows: By pre-designing the position of the straight chain toothed disc and using a color-coded system, users can quickly identify and restore the transmission function in the field or in emergency situations without professional knowledge, which greatly reduces the technical threshold for emergency repair. By using geometric design and chain length pre-calculation, and utilizing the transmission principle of a single-speed bicycle, stable transmission can be achieved without a complex tension adjustment mechanism, ensuring the reliability of the emergency mode. By equipping the chain with a small chain handling tool kit and a length reference rope or pre-cut spare chain, the entire emergency repair process can be completed with only one or two small tools, making it simple and quick to operate and significantly shortening the repair time. This solution requires no additional complex mechanical structures and can be achieved simply through reasonable design planning, a labeling system, and a simple tool configuration. It is low-cost, easy to implement, and highly reliable. The optimized design, including multiple emergency modes and a night-light marking system, further enhances the system's adaptability and operability, making it particularly suitable for use scenarios with high reliability requirements, such as off-road and long-distance cycling. Attached Figure Description

[0017] Figure 1 This is a partial structural schematic diagram of the application of this utility model to an off-road electric bicycle; Figure 2 This is a schematic diagram of the normal operation of a multi-speed bicycle drivetrain. Figure 3 This is a schematic diagram of the transmission system of a multi-speed bicycle when used in this embodiment; Figure 4 This is a structural diagram of the tools in the toolset.

[0018] Figure label: 2. Front sprocket, 3. Rear freewheel assembly, 4. Straight chain sprocket, 5. Chain, 6. Derailleur, 7. Color markings, 9. Tool set, 10. Chain cutter, 11. Quick-connect buckle. Detailed Implementation

[0019] Example

[0020] This invention provides a bicycle transmission system with an emergency fixed gear ratio mode. Under normal circumstances, the system achieves multi-gear shifting via the gearbox 6. When the transmission system malfunctions, it can quickly switch to a fixed gear ratio mode for continued use.

[0021] Reference Figures 1-3 The transmission system includes a front sprocket 2, a rear freewheel assembly 3, a chain 5, and a derailleur 6. The rear freewheel assembly 3 consists of multiple sprockets with different numbers of teeth mounted coaxially, arranged sequentially along the axial direction. The plane of rotation of the front sprocket 2 and the plane of rotation of a specific sprocket in the rear freewheel assembly 3 lie in the same or approximately the same plane; this specific sprocket is called the straight chain sprocket 4. In normal shifting mode, the derailleur 6 drives the chain 5 to switch between the sprockets in the rear freewheel assembly 3 via a chain guide mechanism, thus achieving the shifting function. When the derailleur 6 or the chain 5 malfunctions, the chain 5 can be adjusted to be positioned between the front sprocket 2 and the straight chain sprocket 4, forming the shortest and straightest transmission path. At this point, the tension line of the chain 5 is essentially coincident with or has the smallest angle with the center line connecting the front sprocket 2 and the straight chain sprocket 4, allowing for stable transmission without the guiding action of the derailleur 6.

[0022] Reference Figures 1-4To facilitate quick identification of the chainring sprocket 4 by users, a color-coded marking 7 is provided on the visible surface of the chainring sprocket 4. This marking 7 can be a ring-shaped color strip, a color block, or a reflective material, preferably using high-contrast or fluorescent colors to improve visibility. Simultaneously, corresponding color-coded markings 7 or text descriptions are provided at appropriate locations on the frame, indicating the information of the chainring sprocket 4 required for emergency mode and the corresponding number of chain links. Based on the number of teeth on the front sprocket 2, the number of teeth on the chainring sprocket 4, and the center distance between the front sprocket 2 and the chainring sprocket 4, the number of chain links 5 required for emergency mode is pre-calculated precisely using a standard chain length calculation formula. This chain length is optimized to naturally create appropriate chain tension after installation, ensuring stable operation of the drivetrain. The vehicle is equipped with a chain quick-processing tool set 9, including a chain cutter 10 and a prior art quick-connect buckle 11. The tool set 9 is compact and can be fixedly installed in the frame, seatpost, or tool bag. In addition, the vehicle can be equipped with a standard reference rope, the length of which corresponds to the chain 5 length required in emergency mode. The reference rope can be the same as or related to the color marking 7 of the straight chain sprocket 4 and can be securely stored in a convenient location on the frame. Alternatively, the vehicle can be equipped with a spare chain pre-cut to the accurate length and fitted with a quick-connect buckle 11, further simplifying emergency operation procedures.

[0023] In use, if the derailleur 6 fails or the chain 5 breaks, the user locates the linear chainring 4 according to the color markings 7. Since the chain 5 in normal shifting mode needs to pass through the chain guide mechanism of the derailleur 6, its length is longer than required in emergency mode, thus requiring chain cutting. The user takes out the onboard chain cutter 10. If a length reference rope is provided, compare the reference rope with the broken chain 5 on a flat surface, and use the cutter 10 to cut the chain 5, removing excess links. If no reference rope is available, cut according to the chain link count information marked on the frame. If a pre-cut spare chain is provided, use that spare chain directly. After cutting or preparing, use the quick-connect buckle 11 to connect the two ends of the chain 5 or the spare chain, and manually install the chain onto the front chainring 2 and the linear chainring 4. Because the chain length is precisely designed, the chain will naturally form appropriate tension after installation, similar to the transmission principle of a single-speed bicycle.

[0024] The entire emergency repair process can be completed using only one or two small tools, making it simple and quick to operate.

[0025] Furthermore, in addition to the straight chainring sprocket 4, a second emergency sprocket can be pre-designed in the rear sprocket assembly 3. Although this second emergency sprocket is not completely on the same plane as the front sprocket 2, the chain offset angle is still within an acceptable range. Different color markings 7 are set on the straight chainring sprocket 4 and the second emergency sprocket, for example, the straight chainring sprocket 4 is marked in green and the second emergency sprocket is marked in yellow, allowing users to select different emergency gear ratios according to road conditions. Correspondingly, two reference ropes of different lengths or two pre-cut spare chains are provided, corresponding to the two emergency modes respectively. Each reference rope or spare chain uses the same color marking as its corresponding sprocket for easy identification and use.

[0026] Furthermore, the color markings 7 on the chainring sprocket 4 are made of luminescent or reflective material, providing high-contrast colors during the day and remaining clearly visible at night or in low-light conditions by absorbing and reflecting light. Simultaneously, miniature reference labels corresponding to the color markings 7 on the chainring sprocket 4 are prominently placed on the handlebars or frame, allowing users to quickly confirm the emergency mode configuration in any environment. The reference rope also uses the same luminescent or reflective material to ensure operability in emergency situations in the wild.

[0027] The above description is merely a specific example of this utility model and does not constitute any limitation on this utility model. Obviously, those skilled in the art, after understanding the content and principle of this utility model, may make various modifications and changes in form and details without departing from the principle and structure of this utility model. However, these modifications and changes based on the concept of this utility model are still within the protection scope of the claims of this utility model.

Claims

1. A bicycle transmission system with an emergency fixed gear ratio mode, comprising a front sprocket (2), a rear sprocket assembly (3), a chain (5), and a derailleur (6), wherein the rear sprocket assembly (3) is composed of multiple sprockets with different numbers of teeth coaxially mounted, characterized in that: The rotation plane of the front toothed disc (2) and the rotation plane of a specific toothed disc in the rear flywheel assembly (3) are located in the same or approximately the same plane. This specific toothed disc is defined as a straight chain toothed disc (4). The visible surface of the straight-chain toothed disc (4) is provided with color markings (7) for quick identification; Equipped with a chain quick-processing tool kit (9), the tool kit (9) includes a chain cutter (10) and a quick-connect buckle (11); When the transmission system malfunctions, the chain (5) is cut to a predetermined length and installed between the front toothed disc (2) and the straight chain toothed disc (4) to form a fixed gear ratio transmission. The chain length is determined in advance based on the number of teeth of the front toothed disc (2), the number of teeth of the straight chain toothed disc (4) and the center distance between the front and rear toothed discs, so that the installed chain naturally forms appropriate tension to achieve stable transmission.

2. The bicycle transmission system with an emergency fixed gear ratio mode according to claim 1, characterized in that: The color marking (7) is at least one of a ring-shaped color band, a color block, or a reflective material, and uses a high-contrast or fluorescent color.

3. The bicycle transmission system with an emergency fixed gear ratio mode according to claim 1, characterized in that: Equipped with a length standard reference rope, the length of which corresponds to the chain (5) length required in emergency mode. When in use, the reference rope is compared with the chain (5) on a flat ground or plane to determine the chain cutting length.

4. The bicycle transmission system with an emergency fixed gear ratio mode according to claim 3, characterized in that: The reference rope is the same color as the color marking (7) of the straight chain toothed disc (4) and is fixedly stored in a convenient location on the frame.

5. The bicycle transmission system with an emergency fixed gear ratio mode according to claim 1, characterized in that: A spare chain is provided, pre-cut to the exact length and fitted with a quick-connect buckle (11).

6. The bicycle transmission system with an emergency fixed gear ratio mode according to claim 1, characterized in that: It also includes a frame, on which a color mark or text description corresponding to the color mark (7) of the straight chain toothed disc (4) is provided, indicating the information of the straight chain toothed disc (4) required for emergency mode and the corresponding number of chain links.

7. The bicycle transmission system with an emergency fixed gear ratio mode according to claim 1, characterized in that: A second emergency sprocket is provided in the rear flywheel assembly (3). The chain offset angle between the second emergency sprocket and the front sprocket (2) is within an acceptable range. Different color markings (7) are provided on the straight chain sprocket (4) and the second emergency sprocket.

8. The bicycle transmission system with an emergency fixed gear ratio mode according to claim 7, characterized in that: It is equipped with two reference ropes of different lengths or two pre-cut spare chains, corresponding to two emergency modes. Each reference rope or spare chain is marked with the same color as its corresponding toothed disc.

9. The bicycle transmission system with an emergency fixed gear ratio mode according to claim 1 or 2, characterized in that: The color markings (7) on the straight-chain toothed disc (4) are made of luminescent or reflective materials, and are clearly visible at night or in low-light environments by absorbing light and then emitting light or reflecting light.

10. The bicycle transmission system with an emergency fixed gear ratio mode according to claim 3, characterized in that: A miniature reference label corresponding to the color marking (7) of the straight chain toothed disc (4) is placed in a conspicuous position on the handlebars or frame, and the reference rope is made of luminescent or reflective material.

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