Bicycle Rear Hub Kickback Shifting Without Cables
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Solution Overview
Problem
Existing bicycle transmission systems, particularly those with kickback hubs, are complex and inconvenient, requiring handlebar-mounted shifters and shifting cables that are prone to damage and contamination, making maintenance challenging, especially in rugged environments.
Innovation Solution
A multi-speed transmission system for bicycle wheel hubs featuring a driver with radially arranged drive teeth, a multi-speed freewheel with pawls and bias elements, and a shift ring that alternately blocks engagement of the pawls with the drive teeth, allowing for gear shifting by rotating the pedal shaft in the non-drive direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If handlebar-mounted shifters and shifting cables are used for gear changing, then gear shifting capability is provided, but the system becomes complex and prone to damage and contamination
Solution Approach 1:
The patent removes the handlebar-mounted shifter and shifting cable components from the bicycle transmission system. Instead, gear shifting is achieved by rotating the pedal shaft in the non-drive direction, which directly actuates the freewheel mechanism. This extraction of unnecessary components simplifies the transmission system while maintaining gear shifting capability.
Solution Approach 2:
The transmission system is designed to be self-actuating through the pedal shaft rotation. The rider's natural pedaling motion in the non-drive direction directly engages the pawls with the drive teeth to shift gears, eliminating the need for separate shifter mechanisms. The system uses the existing pedal motion to serve the dual purpose of driving and shifting.
2Ease of operation
If handlebar-mounted shifters and shifting cables are used, then gear shifting is enabled, but maintenance becomes challenging especially in rugged environments
Solution Approach 1:
The patent eliminates the shifting cables and handlebar shifters that require regular maintenance and are susceptible to contamination. The simplified mechanism with exposed pawls and drive teeth can be easily inspected and maintained by simply rotating the pedal shaft, making it suitable for rugged environments.
Solution Approach 2:
The patent employs simple, easily replaceable components such as pawls and bias elements that can be quickly swapped if worn or damaged. This approach prioritizes ease of replacement over long component life, allowing rapid maintenance in field conditions without specialized tools or procedures.
3Adaptability or versatility
If kickback hub transmission is used, then multi-speed capability is provided, but the system becomes complex and inconvenient
Solution Approach 1:
The patent combines the multi-speed transmission function with the existing freewheel mechanism in a single integrated unit. The pawls, bias elements, and drive teeth are all part of the freewheel assembly, eliminating the need for separate hub mechanisms. This merging reduces overall system complexity while maintaining multi-speed adaptability.
Solution Approach 2:
The pedal shaft serves multiple functions: it provides the driving force through chain engagement and simultaneously acts as the actuating mechanism for gear shifting when rotated in the non-drive direction. This multi-functionality reduces the number of dedicated components needed, simplifying the overall transmission system.
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 system provides a robust, low-maintenance, and accessible means to shift gears, eliminating the need for handlebar-mounted shifters and shifting cables, while allowing for efficient operation on various terrains.
Implementation Method 1
a plurality of bias elements arranged radially within an interior area of the second sprocket to bias the plurality of pawls toward the drive teeth
Data Source
AI summary
A system and method for simple transmission of a multi-speed bicycle is provided. A bicycle can have a transmission that can be toggled by a kickback shifting mechanism. A rear wheel hub can support a freewheel having a high speed gear sprocket and a low speed gear sprocket with dedicated chains to create dedicated gear-shifting. Rotating the pedal shaft in the non-drive direction approximately one-quarter rotation can toggle the transmission between the first gear ratio and the second gear ratio with a shifting surface that alternately allows driving engagement of the high speed gear sprocket with the rear wheel driver.