Wireless Bicycle Gear Shift Coordination for Predictable Ratio Changes

Solution Overview

Problem

Wireless electromechanical shifting systems for bicycles face inefficiencies due to unpredictable signal reception and communication latencies, leading to unpredictable gear changes and potential opposite results, such as downshifts instead of upshifts, especially when shifting between sprockets with large radius changes.

Innovation Solution

A wireless drivetrain system with processors and communication devices that coordinate gear changes by generating and transmitting specific signals to control both front and rear gear changers, including recovery shifts and path management within a predetermined shift path, to ensure efficient and predictable gear ratio changes across a broad range.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Weight of moving object

If wireless electromechanical shifting systems are used to decrease system complexity and improve aerodynamics, then weight and streamlined design are improved, but signal reception reliability and communication timing become unpredictable

Engineering Contradiction:

Improvesystem weightVSAvoidsignal reception reliability

Core Design Contradiction:

Weight of moving objectVSReliability

Solution Approach 1:

The system performs preliminary actions by predicting the timing window for signal reception at the rear gear changer and pre-coordinating the front gear changer operation accordingly. The processor determines a time window based on expected signal reception timing, and controls the front gear changer to operate within this predicted window, ensuring reliable coordination despite wireless communication uncertainties.

Inventive Principle:

Principle #10Preliminary action

2Ease of manufacture

If wireless electromechanical shifting systems are used to eliminate cable routing, then ease of installation and maintenance are improved, but communication latencies cause unpredictable gear changes

Engineering Contradiction:

Improveinstallation easeVSAvoidcommunication latency

Core Design Contradiction:

Ease of manufactureVSLoss of time

Solution Approach 1:

The system performs preliminary actions by predicting the timing window for signal reception at the rear gear changer and pre-coordinating the front gear changer operation accordingly. The processor determines a time window based on expected signal reception timing, and controls the front gear changer to operate within this predicted window, ensuring reliable coordination despite wireless communication uncertainties.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system implements feedback by monitoring the actual reception timing of wireless signals at the rear gear changer and using this information to adjust and refine the predicted time window for future operations. This feedback mechanism allows the system to adapt to varying communication latencies and maintain accurate coordination between gear changers.

Inventive Principle:

Principle #23Feedback

3Productivity

If large gear ratio changes are implemented by shifting between sprockets with large radius differences, then drivetrain efficiency is improved, but unpredictable opposite results occur due to communication timing issues

Engineering Contradiction:

Improvedrivetrain efficiencyVSAvoidgear change predictability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The system performs preliminary actions by predicting the timing window for signal reception at the rear gear changer and pre-coordinating the front gear changer operation accordingly. The processor determines a time window based on expected signal reception timing, and controls the front gear changer to operate within this predicted window, ensuring reliable coordination despite wireless communication uncertainties.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system applies preliminary anti-action by anticipating potential timing conflicts between front and rear gear changer operations and preemptively adjusting the coordination strategy. The processor calculates a safe time window that prevents opposite gear changes by ensuring the front gear changer completes its operation before the rear gear changer responds to the wireless signal.

Inventive Principle:

Principle #9Preliminary anti-action

Data Source

PatentUS11015705B2Bicycle control system

Publication Date: 2021.05.25 SRAM LLC

AI summary

A bicycle control system may be provided to control a first gear changer with a control unit and a second gear changer 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.