How does a hidden bicycle motor work?

This is the bike that pedals itself.

We look at the Goat Race, a British-made e-bike designed with the Austrian-made concealed Vivax-Assist motor – the same system used in several recent cases of amateur and international motor doping.

The bike, and motor, are intended for use by normal riders and not in-competition. Vivax-Assist’s main global customers are riders aged over 60 trying to maintain the same level of riding despite losing fitness.

The Vivax-Assist is a hidden power motor within the seattube to power the cranks. The system turns a bevel fastened to the axle of the cranks.

More details of Goat’s Race bike are available at

Note: A mechanical doping infringement occurred at the 2016 UCI Cyclocross World Championships, not 2015 as stated in the video. .