[stdclass]

there are multiple documented cases of motor doping - here you can see wout van aert using motors multiple times in belgian cyclocross races in 2016: https://www.youtube.com/watch?v=rUGNKwcbbDw

[veltas]

That video isn't conclusive and there's a lot of debate in the comments. Personally I agree with the people saying it's explainable.

[stdclass]

in 2 of the instances you can see (if you go in 0.25x) that the wheels start spinning before torque is applied by the pedals - physically impossible. also when wout is running with the bike, it starts spinning after losing traction on the ground