Bicycle Rim Flange Geometry for Pinch Flat Resistance
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Solution Overview
Problem
Existing bicycle wheel rims are prone to pinch flats due to the inner tube being pinched between the rim and external objects, leading to punctures and increased repair costs.
Innovation Solution
The bicycle wheel rim design features a main body with radially extending first and second flanges that cooperatively support the tire, with specific dimensions and geometries such as flange widths, heights, and spacings that help distribute impact and reduce pinch flat occurrences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thicker inner tubes, tire liners, or tire inserts are used to prevent pinch flats, then reliability is improved, but device complexity and weight increase
Solution Approach 1:
The invention extracts the protective function from separate components (thicker tubes, liners, inserts) and integrates it directly into the rim structure through the reinforced flange design. The flange acts as both a structural support and a protective element that prevents tube pinching, eliminating the need for additional protective components.
Solution Approach 2:
The invention merges the structural support function and the pinch flat protection function into a single integrated component - the rim flange. By combining these functions, the design avoids adding separate protective elements while maintaining both structural integrity and protection against pinch flats.
2Reliability
If thicker inner tubes, tire liners, or tire inserts are used to prevent pinch flats, then reliability is improved, but weight increases
Solution Approach 1:
The protective function is extracted from heavy separate components and relocated to the rim flange structure, which already exists and carries the tire. This redistribution of function avoids adding the weight of multiple protective layers while achieving the same protection goal.
Solution Approach 2:
By merging protection and structural support into one component, the invention eliminates the need for additional protective layers that would increase weight. The flange's structural mass serves dual purposes: supporting the tire and preventing pinch flats.
3Device complexity
If traditional rim designs are used, then device complexity is low, but pinch flat resistance is poor
Solution Approach 1:
The invention applies local quality enhancement by reinforcing only the specific area where pinch flats occur - the flange region - rather than redesigning the entire rim. The increased flange width and modified geometry are localized changes that provide protection exactly where needed while maintaining simplicity elsewhere in the rim structure.
Solution Approach 2:
The invention changes key geometric parameters of the flange (increased width, modified height, adjusted curvature) to improve pinch flat resistance. These parameter modifications are made to existing flange structures, maintaining overall design simplicity while achieving enhanced protection through optimized dimensions.
Data Source
AI summary
A bicycle includes a frame, a seat, and at least one wheel rim. The rim includes a main body, and a first flange and a second flange extending from the main body for supporting a tire. A ratio of a first flange width to a flange spacing is at least 0.14. A ratio of an inner corner radius to the first flange width is preferably at most 0.5. A ratio of the first flange width to a first flange height is at least 0.75. The main body includes a cavity having a radial projection that is spaced from a radial projection of the first flange projection by a gap that is at least 10% of the first flange width. The main body further includes a nose section and a first sidewall connecting the nose section to the first flange, wherein the first sidewall includes a first concave outer surface.