Rear Multi-Sprocket Assembly for Smaller Bicycle Sprockets
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Solution Overview
Problem
Conventional derailleur bicycle rear wheel assemblies face limitations in accommodating smaller sprockets due to the geometry of standard drivers, which restrict the number of teeth that can be used, limiting the achievable gear ratio and compatibility with conventional components.
Innovation Solution
A multi-sprocket assembly with a locking screw arrangement that allows for the axial fixation of at least two smallest sprockets with external threads larger than the shank section diameter, enabling more sprockets to be included and overcoming the inner diameter limitations of standard drivers, while maintaining compatibility with conventional drivers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a standard driver geometry is used, then compatibility with conventional components is maintained, but the number of teeth on the smallest sprocket is limited to 11 teeth
Solution Approach 1:
The driver is divided into two distinct sections: a first section with a larger outer diameter for mounting most sprockets, and a second section with a smaller outer diameter specifically for mounting sprockets with fewer than 11 teeth. This segmentation allows the driver to accommodate a wider range of sprocket sizes without requiring a complete redesign of the standard driver geometry.
Solution Approach 2:
Different sections of the driver are designed with different outer diameters to match the specific requirements of different sprocket groups. The first section maintains the standard geometry for compatibility, while the second section provides a reduced diameter to enable smaller sprockets, thus optimizing each local area for its specific function.
2Reliability
If a locking ring is used to fix pinions against axial displacement, then the sprockets are secured, but the inner diameter of the driver is predetermined by the outer diameter of the driver
Solution Approach 1:
The driver's segmented design with two different outer diameter sections allows the locking ring to effectively secure sprockets on the first section while the second section with reduced diameter enables smaller sprockets to be mounted, thus resolving the contradiction between reliable fixation and minimum sprocket size.
Solution Approach 2:
The solution moves from a single-dimension constraint (outer diameter of driver determining minimum sprocket size) to a two-dimension approach by introducing axial segmentation of the driver, allowing different sprocket sizes to be accommodated on different sections while maintaining reliable axial fixation through the locking ring.
Data Source
Figure 1
Figure 2a~2b
Figure 3~4b
AI summary
A multi-gear assembly (10) for a rear wheel assembly (3) for a bicycle with a derailleur gear system comprises a multi-gear arrangement (12) and a locking screw arrangement (14). The multi-gear arrangement (12) is designed for torque-transmitting coupling with a driver (16) of the rear wheel assembly (3) and comprises at least 11 sprockets with varying numbers of teeth. The multi-gear assembly (10) is designed such that, in the assembled state, at least two of the smallest sprockets (R11, R12) are axially fixed to the driver (16) via the locking screw arrangement (14).The locking screw assembly (14) has a shaft section (36) for receiving at least one of the at least two smallest pinions (R11, R12), wherein the shaft section (36) is provided at one end region with an axially external stop section (38) and wherein the shaft section (36) has at least one external thread (40) at its opposite end region, by means of which the locking screw assembly (14) can be screwed into an associated internal thread (34) for fixing the locking screw assembly (14). The external thread (40) associated with the shaft section has an outer diameter (d2) that is larger than an outer diameter (d3) of the shaft section (36) in the region in which the at least one of the at least two smallest pinions (R11, R12) is received.