http://www.nytimes.com/2016/04/19/sp...e-cyclist.html

The first confirmed case of mechanical doping surfaced this year when a tiny motor and battery were found inside a Belgian cyclist’s bike, but that involved cyclocross, a comparatively minor branch of the sport. The latest accusations emerged Sunday on Stade 2, a sports program on the French television network that is also the host broadcaster of the Tour de France. The report suggested that motor doping is also at the highest levels of the sport.
here is some info on electric bicycles:
http://electricbikereport.com/electr...or-comparison/