M Maximum efficiency: >=88% Wheel diameter: Approx. 20in Wheel width: Approx. 4in the rear drive is 170mm. 20inch 48V 1000W E-bike Conversion Kit Rear Wheel Electric Bicycle Hub Motor Set. Type: rear drive DC motor. The rear drive is 170mm. 1 x Shifters Clip. 1 x Binding Post (Yellow Box). France, Germany, spain, Italy. Feedback is very important to us. It is impossible to address issues if we do not know about them! Please keep the original box or packaging within 15days since item received. Your satisfaction is our ultimate goal. We work hard to earn your trust and future business. A If you receive a defective item, you may return it or ask for a discount. Due to time zones, our reply to your questions may not be immediately. If it’s non-workdays, please kindly be patient and wait till Monday. 10 mm 14 mm.