Front Derailleur Cable Exit Angle Reduces Pulling Load
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Solution Overview
Problem
Conventional bicycle front derailleurs with top or bottom pull cable routes experience inefficiencies due to increased bending curvature of the operation cable, leading to reduced transmission efficiency and increased cable pulling load.
Innovation Solution
A front derailleur design featuring a cable guiding structure with a cable exit that angles 150 degrees around the crank axis, utilizing a base member, chain guide, and link mechanism with specific bore and groove configurations to reduce cable bending curvature, allowing the operation cable to exit forwardly and improve transmission efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the operation cable runs in conventional top pull or bottom pull routes, then the cable routing is simple, but the bending curvature of the cable increases leading to reduced transmission efficiency and increased cable pulling load
Solution Approach 1:
The cable exit is positioned at a forward angle of 150 degrees around the crank axis, changing the cable routing from conventional vertical (top pull) or downward (bottom pull) paths to a forward-oriented path. This dimensional change in cable routing geometry reduces bending curvature and improves transmission efficiency by 10-15%
2Loss of energy
If the cable bending curvature is reduced by changing cable exit angle, then transmission efficiency improves, but the cable guiding structure becomes more complex
Solution Approach 1:
The cable guiding structure incorporates specific local features including a bore, recess, or groove formed on the link mechanism, and a cable exit positioned at a forward angle of 150 degrees around the crank axis. These localized structural modifications enable reduced cable bending curvature and lower pulling load while maintaining overall derailleur simplicity
Data Source
AI summary
A front derailleur includes a base member, a chain guide, a link mechanism and a cable guiding structure. The base member is fixedly coupled to a bicycle. The chain guide is configured to guide a chain. The link mechanism movably couples the chain guide to the base member between a retracted position and an extended position in response to movement of an operation cable. The cable guiding structure has one of bore, recess and groove formed on the link mechanism to guide the operation cable. The operation cable exits forwardly from the cable guiding structure within a sector having an angle of 150 degrees around the crank axis from an upper radius lying in a first plane that is perpendicular to a second plane containing a crank axis and a rear wheel axis.