Bicycle Rear Cogset Assembly for Overhang and Rigidity Balance
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Solution Overview
Problem
Modern bicycle gear systems with increased sprocket counts face stress inhomogeneity and deformation risks due to cogset overhangs, leading to irregular operation and structural yielding.
Innovation Solution
An adimensional calculation method is introduced to determine the structural solidity index (K) of the sub-assembly, optimizing the axial lengths and overhangs of the sprocket-carrying body and cogset to balance torque transmission and rigidity, allowing for a larger number of sprockets without compromising structural integrity, with preferred indices between 2 and 6, and specific length ranges for Ls, Sest, and Sest/Sint.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the cogset has greater axial extension (overhang) to accommodate more sprockets, then the number of sprockets increases, but the stress distribution becomes inhomogeneous and structural yielding risk increases
Solution Approach 1:
The patent applies parameter changes by optimizing the axial length of the coupling profile (Ls) relative to the axial length of the cogset (Lp), and by controlling the overhang parameters (Sint and Sest) to maintain the adimensional index K within the range of 2-6. This quantitative parameter optimization allows accommodating more sprockets while maintaining uniform stress distribution and preventing structural yielding.
2Stability of the object's composition
If the axial length of the coupling profile is increased to reduce overhang, then stress distribution improves, but the available space for mounting sprockets decreases
Solution Approach 1:
The patent resolves this contradiction through parameter optimization by establishing the adimensional index K = (Ls/Lp) × (Lc/(Sint+Sest)) within the range of 2-6. This allows the coupling profile length Ls to be sufficiently long for uniform stress distribution, while simultaneously permitting controlled overhang (Sint+Sest) to accommodate additional sprockets. The balanced parameter relationship enables both uniform stress distribution and high sprocket count.
Data Source
AI summary
A sub-assembly is presented, for a bicycle rear wheel, formed by a sprocket-carrying body and a cogset mounted coaxially on the sprocket-carrying body through shape engagement, is sized such that a good compromise is obtained between the ability to house a relatively large number of sprockets and the structural solidity of the sub-assembly.