Bicycle Shifter Angled Lever Mechanism
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Solution Overview
Problem
Conventional bicycle trigger shifters hinder simultaneous braking and shifting in the release direction due to the release lever's placement between the handlebar and brake lever, making it unreachable during brake lever actuation.
Innovation Solution
A trigger shifter design with pull and release levers configured to be actuated by the thumb, featuring a housing mountable to the handlebar, a cable spool, and mechanisms allowing the pull and release levers to rotate in angled planes, enabling simultaneous braking and shifting. The pull lever is longer and provides mechanical advantage, while the release lever is shorter and inclined to facilitate easy thumb operation, with a locking element ensuring gear position retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the release lever is disposed between the handlebar and the brake lever, then the shifter structure is compact, but the release lever becomes unreachable when the index finger is wrapped around the handlebar, preventing simultaneous braking and shifting
Solution Approach 1:
The release lever is repositioned from a horizontal arrangement (between handlebar and brake lever) to a vertical arrangement (below the brake lever). This dimensional change allows the release lever to be accessed by the thumb from below while the brake lever remains accessible from above, enabling simultaneous operation of both controls without spatial interference.
2Force
If the pull lever is made longer to provide mechanical advantage, then shifting requires less force, but the lever mechanism becomes more complex
Solution Approach 1:
The pull lever utilizes the natural dynamic motion of the thumb along an inclined contact surface to provide mechanical advantage. As the thumb moves naturally along the incline during operation, it generates sufficient shifting force without requiring additional mechanical components, thereby reducing overall mechanism complexity while maintaining low force requirements.
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
Enables simultaneous braking and shifting in the release direction by allowing thumb-operated pull and release lever actuation, improving operational convenience and reducing the force required for shifting, while maintaining gear position stability through the locking mechanism.
Implementation Method 1
The pull lever and release lever are biased to return to their rest positions after each actuation
Implementation Method 2
The contact surface of the release lever is partially inclined to allow the thumb to slip along the inclined contact surface when the rider moves his thumb in the riding direction
Data Source
AI summary
A trigger shifter for operating a bicycle gear change device that includes a housing mountable to handlebar, a cable spool for pulling and releasing a control cable connected to the gear change device, a pull lever mechanism and a release lever mechanism. The pull lever mechanism includes a pull lever rotatable about a first axis defining a first plane of motion perpendicular to the first axis. The release lever mechanism includes a release lever rotatable about a second axis defining a second plane of motion perpendicular to the second axis. The first and second planes of motion form an angle therebetween in the range of 20 to 70 degrees.