A bicycle gearshift system is mounted on the rear part of the frame of the bicycle. The bicycle gearshift system includes an electrically powered rear derailleur, a rear hub, a charger part, and a gearshift control part. The electrically powered rear derailleur is mounted on the rear part of the frame....http://www.google.fr/patents/US7042123?utm_source=gb-gplus-shareBrevet US7042123 - Bicycle electrical generator hub
