Composite Bicycle Wheel Spoke Bonding Design
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Solution Overview
Problem
Existing bicycle wheels with metal spokes face challenges in achieving optimal stiffness, low mass, and reduced rotational inertia due to the need for high preloading tensions, which complicates material thickness and weight reduction, and existing composite material solutions are either complex or unreliable.
Innovation Solution
A bicycle wheel design featuring a rim, hub, and spokes made of composite materials, particularly carbon fiber, where spokes are paired two by two and bonded without tension, with variable thickness and adhesive bonding using thermosetting resin, allowing for reduced spoke count and mass while maintaining high stiffness and aerodynamic qualities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If metal spokes with high preloading tensions are used, then wheel stiffness is improved, but material thickness and wheel mass increase
Solution Approach 1:
The patent uses composite material spokes (carbon fiber reinforced polymer) instead of metal spokes. These composite spokes achieve the required stiffness and strength without requiring high preloading tensions, thereby avoiding the need for increased material thickness at the rim edges and reducing overall wheel mass.
Solution Approach 2:
The patent changes the material parameters from metal to composite material, which fundamentally alters the stress-strain characteristics. This allows the spokes to operate at lower tensions while maintaining stiffness, resolving the contradiction between strength and weight.
2Weight of moving object
If composite material spokes with low tensions are used, then wheel mass is reduced, but manufacturing complexity increases
Solution Approach 1:
The patent employs preliminary action by pre-impregnating the carbon fiber strands with thermosetting resin before assembly. This allows the spokes to be manufactured and prepared in advance with the bonding material already in place, simplifying the final assembly process where spokes are simply inserted into the rim and hub holes and cured.
Solution Approach 2:
The patent extracts the bonding process from the spoke manufacturing process itself, separating these two operations. Spokes are manufactured independently with pre-applied resin, then assembled by simple insertion and curing, making the manufacturing process simpler and more reliable.
3Weight of moving object
If adhesive bonding is used to attach composite spokes, then wheel mass is reduced, but bonding reliability may be compromised
Solution Approach 1:
The patent uses thermosetting resin (epoxy-based composite material) as the bonding agent, which provides strong chemical adhesion between the composite spokes and the metal rim/hub. This resin bonding creates a reliable mechanical and chemical connection that maintains structural integrity while keeping the wheel mass low.
Solution Approach 2:
The patent applies local quality by concentrating the bonding action at specific locations - the ends of the spokes where they insert into the rim and hub. The thermosetting resin is applied locally at these insertion points, providing targeted strong bonding exactly where needed for structural reliability.
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
The solution results in a wheel with significantly reduced mass, improved stiffness, and lower rotational inertia, achieving a total mass of approximately 1 kg for a pair of wheels with enhanced manufacturing simplicity and reliability.
Implementation Method 1
injection of a thermosetting binder into the recesses for insertion of the ends of the spokes, and connection of the spokes to the rim and to the hub by polymerization
Data Source
AI summary
A wheel, (1) particularly for a cycle, includes a circular rim (2), a hub (3) concentric with the rim, and spokes (4) connecting the hub (3) to the rim (2). The rim, the hub, and the spokes are made of a polymerized composite material. The spokes (4) are paired two by two on either side of the bond plane of the wheel and are attached without tension at their ends onto the hub (3) and onto the rim (2).