Bicycle Rear Derailleur Offset Friction Axial Width Reduction
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Solution Overview
Problem
Conventional bicycle derailleurs with resistance applying structures often increase the axial width of the movable member, making them bulkier and less suitable for a low profile on a bicycle frame.
Innovation Solution
A rear derailleur design that incorporates a friction applying member offset from the rotational axis, a speed changing mechanism, and torque transmitting wheels with different diameters and tooth counts, allowing for reduced axial width and adjustable rotational speed while maintaining frictional resistance, and optionally including a one-way clutch and electrical actuator for enhanced functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a resistance applying structure is added to conventional derailleurs, then frictional resistance is improved, but axial width increases
Solution Approach 1:
The friction applying member is positioned offset from the rotational axis of the chain guide, utilizing radial space rather than axial space. This dimensional repositioning allows the resistance applying structure to function without increasing the axial width of the movable member, resolving the contradiction between providing frictional resistance and maintaining a compact profile.
2Length of moving object
If the friction applying member is offset from the rotational axis, then axial width is reduced, but torque transmission efficiency may decrease
Solution Approach 1:
The system employs a speed changing mechanism with torque transmitting wheels of different diameters to modify torque parameters. By using a larger diameter wheel on the chain guide side and a smaller diameter wheel on the friction applying member side, the system amplifies the torque from the offset friction application, compensating for the reduced leverage and maintaining effective torque transmission despite the offset positioning.
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 design achieves a reduced axial width, allowing for a low profile on the bicycle frame, adjustable rotational speed, and improved durability and weight reduction, while maintaining effective frictional resistance and chain guidance.
Implementation Method 1
The resistance applying structure includes a friction applying member that applies a frictional resistance to rotational movement of the chain guide
Data Source
AI summary
A bicycle rear derailleur is basically provided a base member, a movable member, a chain guide and a resistance applying structure. The base member is configured to be mounted to a bicycle. The movable member is movably coupled to the base member. The chain guide is rotatably coupled to the movable member around a first rotational axis. The resistance applying structure includes a friction applying member that applies a frictional resistance to rotational movement of the chain guide. The resistance applying structure is offset from the first rotational axis.