Bicycle Gear Changer Coordination for Wireless Shift Timing
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Solution Overview
Problem
Wireless electromechanical shifting systems for bicycles face inefficiencies due to latency and uncertainty in signal reception, leading to unpredictable results and potential opposite outcomes in drive ratio changes, particularly when shifting between sprockets with large radius differences.
Innovation Solution
The system incorporates processors and communication devices in both front and rear gear changers to pause and coordinate shifts, allowing for delayed signal transmission and reception to align shifts, and includes a configuration where one gear changer can transmit signals to another to avoid default mode errors, ensuring predictable and efficient drive ratio changes across a broad range of gear combinations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If wireless electromechanical shifting systems are used to decrease system complexity and improve aerodynamics, then weight and aerodynamic performance are improved, but latency and uncertainty in signal reception occur leading to unpredictable shifting results
Solution Approach 1:
The system implements feedback mechanisms where the first gear changer receives confirmation signals from the second gear changer about the completion of shifting operations. This feedback loop allows the system to detect and correct latency issues, ensuring reliable shifting execution despite wireless communication delays.
Solution Approach 2:
The system performs preliminary actions by sending advance signals between gear changers before actual shifting operations. The first gear changer sends a signal to the second gear changer to prepare for upcoming shifts, and waits for confirmation before executing the next shifting action, thereby preempting potential reliability issues.
2Adaptability or versatility
If wireless electromechanical shifting systems are used to allow flexible component placement, then ease of installation and adaptability are improved, but signal transmission delays and communication uncertainty increase
Solution Approach 1:
The system sends preliminary signals between gear changers to coordinate upcoming shifting operations. The first gear changer notifies the second gear changer in advance, allowing the second gear changer to prepare and confirm readiness before the actual shift occurs, thereby compensating for wireless transmission delays.
Solution Approach 2:
The system maintains continuous communication and coordination between gear changers throughout the shifting process. Rather than discrete, independent shifting actions, the system establishes an ongoing signal exchange that ensures both gear changers are continuously synchronized, eliminating gaps caused by wireless latency.
3Device complexity
If gear changers operate independently without coordination, then device complexity is reduced, but opposite outcomes in drive ratio changes occur leading to inefficient drivetrain operation
Solution Approach 1:
The system implements feedback mechanisms where the first gear changer receives confirmation signals from the second gear changer about the completion of shifting operations. This feedback ensures that gear changes are coordinated and that the drivetrain operates efficiently without conflicting actions.
Solution Approach 2:
The first gear changer acts as an intermediary that coordinates with the second gear changer through signal exchange. By mediating the communication and synchronization between the two gear changers, the system achieves coordinated operation without requiring a complex centralized control system.
4Reliability
If pauses are introduced between controlling gear changer movements and generating motion status signals, then shifting coordination and predictability are improved, but shifting operation time increases
Solution Approach 1:
The system maintains continuous communication and coordination between gear changers throughout the shifting process. Rather than discrete, independent shifting actions, the system establishes an ongoing signal exchange that ensures both gear changers are continuously synchronized, eliminating gaps caused by wireless latency.
Data Source
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Figure 3A~3B
AI summary
A bicycle control system may be provided to control a first gear changer (50) with a control unit (70) and a second gear changer (48) with the first gear changer. The control unit may control both first and second gear changers. The system includes a predetermined shift path and may transition in and out of the predetermined shift path responsive to various controls. Shifts out of the predetermined shift path may be recovery shifts where both first and second gear changers are controlled.