Department - Author 1

Mechanical Engineering Department

Degree Name - Author 1

BS in Mechanical Engineering



Primary Advisor

Sarah Harding


The Smooth Shifters is a team composed of Alex Powers, Brandon Roy Sadiarin, George Rodriguez, and Torey Kruisheer. We are four senior mechanical engineering students at California Polytechnic State University (Cal Poly) in San Luis Obispo, California that are working on a senior design project for Specialized Bicycle Components, Inc. located in Morgan Hill, California. We will be under the advisement of Professor Sarah T. Harding of the mechanical engineering department at Cal Poly.

Specialized, one of today’s leading bicycle companies, is in need of a test setup that measures brake and shifter cable drag. High performance cyclists using time trial, triathlon, and aero bikes are constantly looking for ways to have as much aerodynamic advantage as possible, paired with a low profile look on their bicycles. To address these issues, bicycle companies have started a new trend of routing cables inside of the bicycle frames, rather than running them outside the frames. Unfortunately, routing a cable through a bicycle’s frame causes additional cable drag which ultimately decreases shifting and braking performance. Specialized has requested a test setup that can be used to determine cable drag in any cable configuration prior to the fabrication of a physical prototype.

The goals of this project are:

  1. To create a physical system to accurately mimic cable routing of a Specialized Tarmac bicycle frame and a comparative tool to measure the cable drag in competing systems.

  2. To create a simulation environment which allows a user to build a cable system to check performance without a physical test apparatus. A database of different routing systems and components can then be built up over time for continuous use with different frames.