Spring Rate Measurement of a Pneumatic Mountain Bike Tire

Author(s) Information

Joseph D. Balderama, California Polytechnic State University, San Luis ObispoFollow
Alexandre Kachlakev, California Polytechnic State University, San Luis ObispoFollow
Duncan Wyke, California Polytechnic State University, San Luis ObispoFollow
Luki Rosen, California Polytechnic State University, San Luis ObispoFollow

College - Author 1

College of Engineering

Department - Author 1

Mechanical Engineering Department

Degree Name - Author 1

BS in Mechanical Engineering

College - Author 2

College of Engineering

Department - Author 2

Mechanical Engineering Department

Degree - Author 2

BS in Mechanical Engineering

College - Author 3

College of Engineering

Department - Author 3

Mechanical Engineering Department

Degree - Author 3

BS in Mechanical Engineering

College - Author 4

College of Engineering

Department - Author 4

Mechanical Engineering Department

Degree - Author 4

BS in Mechanical Engineering

Date

6-2024

Primary Advisor

Andrew Kean, College of Engineering, Mechanical Engineering Department

Abstract/Summary

The Final Design Review (FDR) presents a comprehensive overview of the spring rate measurement project for a pneumatic mountain bike tire. This report details the project's design, its implementation, and how it met all specified requirements. It also includes a discussion of the project's findings and recommendations for future work, assuming continuation of the project. The primary goal is to develop a device that allows professional race teams or experienced mountain bike riders to parameterize tires based on their spring rate in addition to internal pressure.

Since the Critical Design Review (CDR), the design has undergone significant changes due to a switch to an in-line load cell from the original S-beam load cell. This design change allowed for a reduction in the overall dimensions and weight of the product, while still meeting the force requirements.

The project involved manufacturing various dynamic components including upper and lower bearing adapters as well as static components such as the wheel axle and frame. Most parts were custom-made using both subtractive and additive manufacturing processes. The electrical components used include the load cell, Arduino microcontroller and supporting products. This report verifies the design specifications by detailing each of the test guidelines.

The final design exceeded expectations in many areas but raised concerns about the design of the force application system. The switch to the smaller load cell initially introduced buckling of the force application system and eventual failure of the load cell as a result. A slight redesign was introduced to eliminate possible load cell failure. Key takeaways from the project include the importance of teamwork, a broad understanding of manufacturing processes, allowing sufficient project time for unexpected issues, and avoiding last-minute design changes.

For future work, we recommend modifying the design of the force application system actuation to eliminate buckling entirely. Additionally, collecting sufficient data will enable us to properly recommend a range of values to achieve consistent parameterization, aligning with the project's scope.

URL: https://digitalcommons.calpoly.edu/mesp/762