Bicycle Gearshift Actuation Device with Spring Return Mechanism
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional bar-end devices for bicycle gearshifts require complex mechanisms to return the control lever to its neutral position, which complicates aerodynamics in racing bicycles.
Innovation Solution
A ratchet mechanism with rocker arms and a cam profile system, combined with a spring thruster, allows the control lever to automatically return to its neutral position after gearshifting, using a toothed crown and indexing means to maintain angular positions of the cable-winding bobbin.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a complex mechanism is used to return the control lever to its neutral position, then the lever can be reliably returned to neutral, but the device complexity increases and aerodynamics are compromised
Solution Approach 1:
The patent extracts the return-to-neutral function from a complex mechanism and implements it through a simple spring element. The spring is mounted on the casing and acts directly on the lever to return it to the neutral position, eliminating the need for complex return mechanisms while maintaining reliability.
Solution Approach 2:
The spring element provides automatic return-to-neutral functionality without requiring additional actuators or complex mechanisms. The system uses the spring's inherent elastic properties to self-return the lever, simplifying the overall device while ensuring reliable neutral position return.
2Reliability
If a complex mechanism is used to return the control lever to its neutral position, then the lever can be reliably returned to neutral, but the aerodynamics are compromised in competitive cycling
Solution Approach 1:
The patent removes complex return mechanisms that would create aerodynamic drag and replaces them with a simple spring element. This extraction of unnecessary complexity directly reduces aerodynamic resistance while maintaining the reliable return-to-neutral function through the spring's elastic action.
3Measurement precision
If the control lever is directly connected to the cable-winding bobbin, then the angular positioning is precise, but the mechanism to return the lever to neutral becomes complex
Solution Approach 1:
The patent segments the control mechanism into distinct functional elements: the lever for user input, the spring for return-to-neutral, and the indexing mechanism for angular positioning. This segmentation allows each element to perform its function independently, maintaining precise angular positioning while simplifying the return mechanism.
Solution Approach 2:
The spring element acts as an intermediary between the lever and the neutral position, providing a simple yet effective return mechanism. This intermediary component eliminates the need for complex return mechanisms while preserving the precise angular positioning achieved through the indexing mechanism.
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
Simplifies the control mechanism, enhancing aerodynamics by allowing smooth return to the neutral position without direct connection to the bobbin, ensuring efficient gearshifting and reducing mechanical complexity.
Implementation Method 1
a spring element, mounted on the casing, acting on the lever to return it into the neutral position
Implementation Method 2
A ratchet mechanism with rocker arms and a cam profile system, combined with a spring thruster, allows the control lever to automatically return to its neutral position
Data Source
AI summary
The disclosed device controls a cable associated with a bicycle gearshift and is particularity configured for securing the body of the device on the forward-facing end of racing bicycle handlebars. A cable winding bobbin, having an internally toothed crown, is provided in the device's body and a drive mechanism rotates the bobbin in the chosen direction to achieve predetermined angular positions. A ratchet mechanism, located between the lever and the toothed crown, includes opposite rocker arms with cam profiles curved away from each other, and a toothed sector for engaging the toothed crown. A pointer is located to be selectively engaged with at least one of the rocker arms so that engagement results in the rocker arm's toothed section being away from the toothed crown, and disengagement results in the rocker arm's toothed section being engaged with the toothed crown.