Central Washington University Mechanical Engineering Technologies Capstone Project

By: Kyle Wright

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Problem

On a multi speed bicycle a component called a cassette is located on the drive side of the rear wheel.

There are two issues with the process of removing a cassette from a bicycle rear wheel. First issue, it takes considerable force to loosen the cassette lock ring. Second, tools that require the use of both hands are needed during loosening of the cassette lock ring.

 

Motivation

The ergonomic challenges that bike mechanics and at home DIY bike enthusiasts face while trying to remove a cassette from a rear bike wheel give motivation for development of a new set of processes and tools.

 

Function Statement

A device that will allow single handed removal of a bicycle cassette.

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Abstract

Removal of a bicycle cassette requires additional tools to hold the cassette in place while loosening the cassette lockring. Typically a tool called a chain whip is used to stabilize the cassette, but is difficult to quickly and correctly apply to the cassette. Due to the need for an additional tool to hold the cassette, the user is faced with utilizing both hands while still needing to somehow hold the wheel in place. The lockring is torqued relatively tight and the overall combination of force, ergonomics, and number of tools required makes the task difficult to perform quickly. The objective was to create a device that simultaneously holds the cassette in place while also loosening the lockring thus eliminating the need for a chain whip. This device also utilizes a gear set to reduce user imputed toque. By using the cassette’s mechanical function of non-clockwise free rotation in relation to the wheel itself, a stable motionless platform is created to apply a moment in clockwise direction while a torque multiplying gear set converts the clockwise rotation to counter clockwise rotation which loosens the lockring. User applied torque is reduced by 50% compared to traditional methods. The device also increases the ergonomics of the task and improves overall task completion time by 33%. Eliminating the use of a separate cassette holding tool improves simplicity of the task.