Asymmetric Bicycle Rim Profile for Higher Stall Angles
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Solution Overview
Problem
Existing bicycle wheels are inefficient in maintaining aerodynamic performance across a range of wind angles due to limited stall angles, leading to increased drag and energy expenditure for cyclists.
Innovation Solution
The design of aerodynamic bicycle rims and wheels with a wider cross-section than the tire at the outer edge, featuring a tangent line that is tangent to both the tire and the sidewall, allowing for increased stall angles and reduced drag.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional narrow rim designs are used, then manufacturing is simpler, but aerodynamic efficiency deteriorates due to limited stall angles and increased drag
Solution Approach 1:
The patent changes the geometric parameters of the rim cross-section, specifically making the rim wider than the tire at the outer edge and positioning the widest portion away from the tire contact patch. This parameter change increases the stall angle and reduces drag by optimizing airflow characteristics over the wheel assembly.
Solution Approach 2:
The patent employs asymmetric rim design where the cross-section is not uniform around the wheel. The widest portion of the rim is positioned at a specific location away from the tire contact patch, creating an asymmetric shape that optimizes aerodynamic performance by controlling flow separation and reducing wake turbulence.
2Object-affected harmful factors
If rim width is increased beyond tire width, then aerodynamic efficiency improves through increased stall angles, but device complexity increases
Solution Approach 1:
The patent applies local quality by making the rim wider than the tire only at specific locations (the outer edge and with the widest portion positioned away from the contact patch), while maintaining appropriate width elsewhere. This localized width increase optimizes aerodynamics without unnecessarily complicating the overall rim structure or compromising other functional requirements.
3Reliability
If conventional rim shapes are used, then tire adhesion is adequate, but aerodynamic performance deteriorates at side wind angles
Solution Approach 1:
The patent addresses aerodynamic performance in the lateral dimension by positioning the widest portion of the rim away from the tire contact patch. This dimensional arrangement creates a specific flow pattern that delays flow separation at side wind angles, increasing the stall angle and reducing drag while maintaining tire adhesion through proper contact patch geometry.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design enhances aerodynamic efficiency by increasing stall angles, reducing drag, and improving tire adhesion and side support, thereby enhancing cycling performance and safety.
Implementation Method 1
Drag or wind resistance is a major force acting against the movement of a cyclist
Implementation Method 2
side winds cause air flow to come from angles to the side of the wheel, causing previous wheels to stall and lose aerodynamic efficiency
Data Source
AI summary
An aerodynamic bicycle rim comprising: a circumferential outer portion comprising a circumferential outer surface, the circumferential outer portion adapted to seat a bicycle tire; a nose; and a set of sidewalls, each sidewall extending radially from the nose of the aerodynamic bicycle rim to a corresponding transition to the circumferential outer surface to form a rim body having a maximum rim body width that is greater than a maximum width of the bicycle tire. The aerodynamic bicycle rim is operable to seat the bicycle tire so that the aerodynamic bicycle rim and the bicycle tire form an asymmetrical cross-sectional shape.