An electric power unit for two-wheel vehicles comprising a batteries housing, from which current is supplied to a DC magnetic motor that is connected to a controller assembly, and a chain transmission driven by the DC magnetic motor, which is adapted to actuate a driven wheel of a two-wheel vehicle....http://www.google.co.uk/patents/US6814172?utm_source=gb-gplus-sharePatent US6814172 - Electric power unit for two-wheel vehicles
