Very frustratingly I can't now find the video, but it was a steel bike set up with the rear wheel off the ground. They loaded the pedal until the frame flexed considerably, and then when released the energy from the frame went into the drivetrain and the rear wheel starting rolling.
When I'm not on my desktop I'll try to find it.
Last edited by Piff; 12-09-23 at 01:39 PM.