Torque Element Integrated into Bicycle Dropout Recess
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Solution Overview
Problem
Existing motor-driven electric bicycles face issues with torque arms failing due to excessive motor torque, leading to axle rotation and potential injury from tangled wires.
Innovation Solution
A bicycle design featuring a wheel axle with a torque element secured to the axle and housed within a recessed dropout, preventing rotation by engaging with the dropout's converging walls, thereby inhibiting axle rotation relative to the frame.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a torque arm is externally bolted to the frame using a special connector, then axle rotation is prevented, but the torque arm is prone to failure and can cause injury when it fails
Solution Approach 1:
The torque reaction force is extracted from the external torque arm and transferred directly to the frame through the dropout structure. The recess in the dropout engages with the torque element on the axle, eliminating the need for a separate external torque arm and its vulnerable wire connections.
Solution Approach 2:
The torque transfer function is merged with the dropout structure by incorporating a recess directly into the dropout. This combines the wheel mounting function and torque reaction function into a single integrated structure, eliminating the separate torque arm component.
2Reliability
If the torque element is secured within the recess of the dropout, then axle rotation is inhibited, but the device complexity increases
Solution Approach 1:
The dropout structure serves multiple functions: it mounts the wheel to the frame and simultaneously transfers torque reactions to the frame through the recess. This multi-functionality eliminates the need for separate torque arm components, reducing overall device complexity.
Solution Approach 2:
The torque element is nested within the recess of the dropout, with the torque element fitting inside the recess space. This nested arrangement allows the torque transfer mechanism to be contained within the existing dropout structure without adding external components.
Data Source
AI summary
A bicycle including a wheel that has an axle with a first end and a second end, a motor coupled to the axle, and a frame supported by the wheel. The frame includes a first dropout and a second dropout, and the first dropout defines a recess. The bicycle also includes a torque element that is secured to the first end of the axle and that is shaped to fit within the recess of the first dropout to inhibit rotation of the axle relative to the frame in response to torque from the motor.