Electric Bike 750W Mid Drive Motor Conversion 52V Torque Sensor Throttle EBBS02. Mid drive kit like Bafang BBS02 but with torque sensor – the harder you pedal the more power it gives. This is a rare item now as production has ceased. The motor is made by ex-engineers from bafang. It is not a pure torque sensor. Like most modern bikes it adjusts the power assist based both on pressure on the pedals and the rate the pedals are turning. Apparently 60% PAS and 40% torque. Bottom bracket size is 68-73mm. Chainweel is 42 teeth but you can use any standard 130 bcd chainweel. Max torque is 90 Nm. Max speed is 40kph.