LiFepo4 batteries are the only way to go but must have BMS & that BMS must be capable of continious current for the motor under load I buy from site BMSBatteries China http://www.bmsbattery.com/get the big BMS make up battery myself in 2 tubes that will fit any mountain bike its cost money to learn but this with either 500w cyclone or 1200w the only way to go



----I now have Nu Vinci What a machine, streets, cars,traffic lights , & intersections so quick & safe as ones mind is not thinking at all on gears.