The completed project, without the power supply and PC104 stack. The motor is mounted to the frame just below the seat and the hall effect sensor is mounted just behind the front cog.

Project Overview

Adding an automatic transmission to a bicycle means that the rider no longer has to think about shifting gears and can concentrate more on their surroundings and safety. The design implementation we selected was chosen to replace the shift levers for user input with a motor that pulls or releases the derailleur cable as needed to shift gears. Gear changes occur automatically, with no additional input from the rider.

The desired gear is selected based on sensory input about the rider's current cadence (pedal RPM). Shifting occurs when a rider pedals slower or faster than a desired RPM range. The software determines the appropriate time to shift and signals the motor to perform the task. Once the bike has shifted, the system allows a brief period for the rider to adjust to the change before making another shifting determination.

Our group would like to thank Professors Lynch and Peshkin, Rich Dojutrek, and Bob Taglia for their time, advice, and of course, loaning us the bicycle for the quarter!