Bicycle Shifter Lever Return Mechanism for Aerodynamic Drag Reduction
Solution Overview
Problem
Bicycle shifters mounted on hook-type handlebars in time trial bicycles do not return to a neutral position after each shift operation, increasing aerodynamic drag and complicating the design, which is not ergonomic.
Innovation Solution
A bicycle shifter with a housing, takeup member, control mechanism, holding mechanism, and return assembly that mounts near the handlebar end, featuring a rotatable control lever, driver, clutch mechanism, and biasing members to return to a neutral position after each shift, reducing aerodynamic drag and improving ergonomics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the shifter lever does not return to a neutral position after each shift operation, then the gear shifting function is maintained, but the aerodynamic drag increases and the design becomes more complicated
Solution Approach 1:
The shifter lever is designed to dynamically return to a neutral position after each shift operation through a return assembly including springs and cam mechanisms. This dynamic restoration ensures the lever consistently returns to an aerodynamic neutral position, reducing drag while maintaining functional complexity only where necessary for the return mechanism
Solution Approach 2:
The return assembly with springs and cams enables the shifter lever to automatically return to its neutral position without rider intervention. The system self-corrects its position after each shift, eliminating the need for manual resetting and ensuring consistent aerodynamic positioning
2Ease of operation
If the shifter lever does not return to a neutral position after each shift operation, then the gear shifting function is maintained, but the ergonomics deteriorate
Solution Approach 1:
The control mechanism incorporates a return assembly that dynamically restores the lever to its ergonomic neutral position after each shift. This ensures the lever is always positioned for optimal rider comfort and control, with the return mechanism automatically managing the restoration without adding significant operational complexity
Solution Approach 2:
The shifter system automatically returns the lever to its ergonomic neutral position through spring and cam mechanisms, eliminating the need for rider intervention. This self-restoring capability maintains ergonomic positioning while keeping the operational interface simple and intuitive
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 shifter effectively reduces aerodynamic drag and enhances ergonomics by returning to a neutral position after each operation, allowing for efficient gear shifting with reduced complexity and improved rider comfort.
Implementation Method 1
a rotational biasing member for rotationally biasing the clutch mechanism to a neutral position
Implementation Method 2
an axial biasing member for axially biasing the clutch mechanism to a neutral position
Data Source
Figure 1~2
Figure 3
Figure 3a
AI summary
A bicycle shifter (10) for pulling and releasing a control cable (12) connected to a gear change mechanism mountable at or near an end (24) of the handlebar (26) that returns to a neutral position after each shift operation to decrease aerodynamic drag encountered by the rider. The shifter (20) includes a takeup member (18), a control mechanism (16), a holding mechanism (20) and a return assembly (22). The takeup member (18) is rotatable about a shift axis for winding and unwinding the control cable (12) thereon in a cable-pull direction and a cable-release direction. The control mechanism (16) is movable in a first direction to rotate the takeup member (18) in the cable-pull direction and in a second direction to rotate the takeup member (18) in the cable-release direction. The holding mechanism (20) retains the takeup member (18) in a selected position and the return assembly (22) returns the control mechanism (16) to the neutral position after each shift operation.