Multi-Sprocket Chain Orientation for Precise Bicycle Gearshifts
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Solution Overview
Problem
Conventional multi-sprocket arrangements for bicycle rear wheel hubs face challenges in precise chain overgearshifts under high operating loads, leading to vibrations, wear, and potential drivetrain damage due to deviations from tangential conditions, especially with large transmission ratio steps.
Innovation Solution
A multi-sprocket arrangement with sprockets of different diameters featuring corrective features such as riding-up teeth and gearshift channels, which ensure a predetermined chain link plate orientation, allowing for precise chain overgearshifts and reduced vibrations, even under high loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional multi-sprocket arrangements are used with large transmission ratio steps, then a wide gear range is achieved, but chain vibrations and wear increase due to deviations from tangential conditions during gearshift
Solution Approach 1:
The sprocket teeth are designed with differentiated local properties: some teeth have increased height (riding-up teeth) to engage with wide chain links, while others have standard dimensions for narrow chain links. This local variation in tooth geometry enables the sprocket to accommodate different chain link types at different positions, ensuring proper tangential engagement during gearshift operations while maintaining a wide transmission ratio spread across multiple sprockets.
Solution Approach 2:
The drive chain is segmented into alternating wide and narrow chain links, which interact differently with the sprocket teeth. This segmentation allows the chain to engage with specific tooth types during gearshift, with wide links engaging riding-up teeth and narrow links engaging standard teeth, thereby maintaining precise tangential conditions even during outboard gearshifts between sprockets with large transmission ratio steps.
2Adaptability or versatility
If outboard gearshift from large sprocket to small sprocket is performed with large transmission ratio steps, then wide gear range is achieved, but chain does not run tangentially causing skewed running and vibrations
Solution Approach 1:
Riding-up teeth with increased height are strategically positioned on sprockets to engage with wide chain links during outboard gearshift operations. This local modification ensures that when the chain transitions from a larger sprocket to a smaller sprocket with a large transmission ratio step, the wide chain link engages the riding-up tooth, maintaining tangential alignment and preventing skewed running and vibrations.
3Ease of manufacture
If standard sprocket teeth design is used, then manufacturing is simple, but chain guidance is insufficient under high drive loads
Solution Approach 1:
Instead of modifying the entire sprocket, only specific teeth are designed with increased height (riding-up teeth) while others maintain standard dimensions. This localized modification provides enhanced chain guidance stability under high drive loads where needed, while keeping the overall manufacturing process relatively simple and maintaining compatibility with standard chain link dimensions.
Data Source
AI summary
A drive arrangement for a bicycle has a multi-sprocket arrangement for a rear wheel hub of the bicycle. The multi-sprocket arrangement comprises a plurality of sprockets with different diameters, wherein the sprockets each have a plurality of teeth which are separated by tooth spaces and which can be placed in engagement with a drive chain with wide and narrow chain links which follow one another alternatively in succession. On at least one sprocket, a corrective feature is provided which is designed such that the drive chain, as it revolves around a selected sprocket or during a sprocket changeover from a starting sprocket to a selected sprocket, is oriented, with regard to its wide and narrow chain links, in a predetermined chain link plate orientation relative to the teeth of the selected sprocket.