Multiple Sprocket Tooth Geometry for Smoother Bicycle Shifting
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Solution Overview
Problem
Bicycle sprockets face challenges in smooth shifting operations due to chain curvature issues, leading to engagement problems between sprocket teeth and the bicycle chain, particularly during shifting between different sprockets.
Innovation Solution
The bicycle multiple sprocket design incorporates a second sprocket with chain-curvature limiting teeth and chamfered portions to support the inner link plate of the bicycle chain, preventing engagement of first sprocket teeth into the outer link space and reducing chain curvature, thereby facilitating smoother shifting operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the bicycle chain is shifted from the second sprocket to the first sprocket, then the shifting operation is facilitated, but the first sprocket tooth may unintentionally engage into the outer link space of the chain
Solution Approach 1:
The chain-curvature limiting surface acts as an intermediary element between the second sprocket and the bicycle chain. It mediates the interaction by supporting the inner link plate and controlling the chain's curvature during shifting, preventing the first sprocket tooth from engaging the outer link space while facilitating smooth shifting operation.
Solution Approach 2:
The chain-curvature limiting surface changes the geometric parameters of the chain path during shifting. By constraining the chain curvature to a specific range, it modifies the spatial relationship between the chain and sprocket teeth, preventing unintended engagement while enabling controlled shifting.
2Ease of operation
If the chain curvature is reduced during shifting, then the shifting operation becomes smoother, but the chain may not properly engage with the sprocket teeth
Solution Approach 1:
The chain-curvature limiting surface optimizes the chain curvature parameter during shifting. It maintains the curvature within a specific range that allows both smooth shifting operation and proper chain-sprocket tooth engagement, resolving the contradiction between smoothness and engagement reliability.
Solution Approach 2:
The chain-curvature limiting surface prepares the chain in advance by guiding its curvature before the actual engagement with the first sprocket. This preliminary positioning ensures that when shifting occurs, the chain is already in the optimal configuration for smooth transition while maintaining proper engagement geometry.
Data Source
AI summary
A bicycle multiple sprocket comprises a plurality of sprockets. The plurality of sprockets includes a first sprocket and a second sprocket. The second sprocket includes a second sprocket body and a plurality of second sprocket teeth extending radially outwardly from the second sprocket body with respect to the rotational center axis. The plurality of second sprocket teeth includes at least one chain-curvature limiting tooth having a chain-curvature limiting surface configured to support an inner link plate of a bicycle chain in the axial direction in a chain-inclining state where the bicycle chain is inclined from the at least one chain-curvature limiting tooth toward the first sprocket so as to prevent one of a plurality of first sprocket teeth from engaging in an outer link space provided between an opposed pair of outer link plates of the bicycle chain.