An open source telemetry system using downhill mountain biking as an inspiration.


Modern downhill bikes have a lot of adjustability but their performance is hard to measure. If there was a system to collect data it would be easy to make adjustments with a scientific approach. Riders could also get feedback on their riding style and line choices. It could also add to the entertainment side of things by providing realtime telemetry for spectators.

Possible Telemetry

  • suspension compression rates
  • suspension rebound rates
  • wheel speed
  • when brakes are applied
  • gear selection
  • crank rotation
  • handbar direction
  • wheel deflection
  • tire pressure


  • high velocities
  • hi duty cycles
  • hostile environment (cold/wet/dust/mud/heat)
  • needs to support quick mounting/unmounting
  • frequent vibrations
  • large sudden impacts

Our approach

  1. Try and use cheap, off the shelf sensors
  2. Create a string encoder using a retractable key badge with a capacitve encoder. This improves on some of the existing diy string potentiometer approaches. The main benefits of our approach is higher duty cycles of the equipment and less friction for the retraction of string.
  3. Use the vent holes on the disc brakes with an ir gate for optical encoding to infer wheel speed
  4. Setup a 9 degrees of motion imu on the frame to use as a referrence point for front and rear wheel activity


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