A friction-ring gear unit for a vehicle that is operable by motor power and/or pedaling power, in particular for an electrical bicycle having an electric motor, comprising a crankshaft for pedal cranks, and an inner friction ring (26) and an outer friction ring, as well as at least one rotatable dualcone roller which is situated on a roller carrier and is in frictional engagement with the inner friction ring and the outer friction ring, the friction-ring gear unit being situated coaxially around the crankshaft.