Bicycle Sprocket Support Structure for Chain Drop Interception
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Solution Overview
Problem
The 'chain drop' phenomenon, where the transmission chain disengages from the sprocket assembly, particularly from the largest diameter sprocket, can cause the rear wheel to lock, posing a safety risk and complicating repositioning, especially when the chain jams between the sprocket and spokes.
Innovation Solution
A supporting assembly that projects axially beyond the inner surface of the largest toothed wheel to support the chain at a predetermined radial distance from the hub, preventing jamming and allowing free rotation of the rear wheel by intercepting the chain in case of a drop.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the chain drop prevention device intercepts the chain at a radial distance closer to the sprocket, then it can prevent chain jamming more effectively, but it may interfere with the transmission chain during normal operation
Solution Approach 1:
The supporting assembly is designed with specific geometric characteristics (radial distance, axial projection) that create a localized support zone only in the chain drop scenario. The support structure provides targeted intervention at a specific radial distance from the sprocket axis, ensuring it only activates when needed without affecting normal chain operation on the sprocket teeth.
Solution Approach 2:
The supporting assembly acts as an intermediary element between the sprocket and the chain during a chain drop event. It provides a intermediate support surface that catches the chain before it can jam against the spokes, mediating the chain's path and preventing harmful contact while remaining invisible to normal chain-sprocket engagement.
2Reliability
If a supporting assembly projects axially beyond the inner surface of the largest toothed wheel, then it can support the chain and prevent jamming, but it increases the device complexity
Solution Approach 1:
The supporting assembly is merged with the largest toothed wheel (sprocket) of the sprocket assembly, forming an integrated structure. The support elements are combined with the sprocket body or its mounting structure, eliminating the need for separate chain support devices and reducing overall system complexity while maintaining chain drop prevention functionality.
Solution Approach 2:
The largest toothed wheel serves dual functions: it acts as a functional sprocket for chain transmission during normal operation and simultaneously serves as the mounting base for the chain drop prevention supporting assembly. This multi-functionality reduces the number of separate components needed in the system.
3Reliability
If the supporting assembly is positioned at a radial distance that intercepts the chain, then it prevents chain jamming between sprocket and spokes, but it may affect the free rotation of the rear wheel
Solution Approach 1:
The supporting assembly creates a localized support function at a specific radial distance from the wheel axis, providing chain interception capability only in the chain drop scenario. The support structure's geometric parameters (radial position, axial projection distance) are optimized to provide chain support without creating friction or mechanical interference with the freely rotating wheel and its spokes.
Solution Approach 2:
The space between the sprocket assembly and the wheel spokes is functionally segmented into different zones: a normal operation zone where the chain engages the sprocket teeth, and a chain drop zone where the supporting assembly provides backup support. This spatial segmentation allows independent optimization of each zone's function without mutual interference.
Data Source
AI summary
A sprocket assembly component with at least one first toothed wheel configured to have the most teeth of the sprocket assembly. The first toothed wheel has an axially inner surface and a supporting assembly that extends in the axial direction up to a free end arranged axially more internally with respect to the axially inner surface of the first toothed wheel.