Bicycle Shifting Device Preventing Miss-Shifts via Cable Segmentation
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Solution Overview
Problem
Conventional bicycle control cables, such as Bowden cables, often lead to miss-shifting or miss-upshifting operations during multiple shifting operations due to the lack of precise control over cable movement, particularly at changing points.
Innovation Solution
A bicycle operating device with a base member, cable control bodies, positioning mechanisms, an operating member, and an input mechanism that includes a pulling pawl structure and cam members to selectively engage and disengage the cables, preventing movement over specific predetermined positions and ensuring accurate shifting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional Bowden cable is used for bicycle control, then the structure is simple and easy to manufacture, but miss-shifting or miss-upshifting operations occur during multiple shifting operations due to lack of precise control over cable movement
Solution Approach 1:
The cable control body is divided into multiple segments corresponding to different predetermined positions (first, second, third positions). Each segment can be independently controlled and positioned, allowing precise control over cable movement at each shifting stage. The segmentation enables the system to prevent miss-shifting by ensuring the cable reaches exactly the intended position without overshooting or undershooting.
Solution Approach 2:
The positioning mechanisms are designed to preliminarily establish the cable control body at specific predetermined positions before the actual shifting operation occurs. The restricting structure preliminarily prevents the cable from moving beyond certain positions during the shifting process, ensuring accurate positioning is achieved before the shifting is complete.
2Ease of operation
If the cable control body is allowed to move freely during multiple shifting operations, then the operation is simple and fast, but miss-shifting occurs at changing points where operation switches between different cable control bodies
Solution Approach 1:
The restricting structure acts as an intermediary between the operating member and the cable control body at changing points. It mediates the transition by selectively prohibiting cable movement when the operating member approaches a changing point, preventing miss-shifting while allowing normal operation at other times. This intermediary function maintains operational simplicity while ensuring reliability.
Solution Approach 2:
The system incorporates feedback through the positioning mechanisms that detect when the cable control body reaches predetermined positions. This feedback information is used by the restricting structure to determine when to prohibit further cable movement, creating a closed-loop control system that prevents miss-shifting while maintaining ease of operation.
3Reliability
If a restricting structure is added to prevent cable movement at changing points, then miss-shifting is prevented, but the device complexity increases
Solution Approach 1:
The restricting structure is merged with the existing input mechanism components rather than being a completely separate addition. The positioning mechanisms and restricting structure share common elements with the cable control body and operating member, consolidating functions into a unified system that prevents miss-shifting without proportionally increasing overall complexity.
Data Source
AI summary
A bicycle operating device includes a base member, first and second cable control bodies, first and second positioning mechanisms, an operating member and an input mechanism. The first positioning mechanism selectively maintains the first cable control body in a first predetermined position. The second positioning mechanism selectively maintains the second cable control body in a second predetermined position. The input mechanism moves the first and second cable control bodies between the first and second predetermined positions in accordance with a predetermined operation sequence having a changing point to change operation from the first cable control body to the second cable control body. The input mechanism moves the first cable control body by at least two of the first predetermined positions in a single continuous operation of the operating member. The input mechanism includes a restricting structure that prohibits movement of the first cable control body at the changing point.