Important NOTE:This item is for the bike that uses the hub diameter less than 36mm(1.42 inch).This item doesn't include battery or charger.This is our newest kit for electric common bike, this kit mounts the sprocket on the wheel spokes, so it fits most of bicycle wheel.During installation, the two transmission wheels need to be adjusted to a straight line. The deviation of flywheel angle will tilt the flywheel stress point to one side, causing flywheel damage. The flywheel angle is generally adjusted through the mounting bracket of the motor.Motor use freewheel so when wheel rotating, the motor will not rotate, just like a normal bike, this can reduce resistance.The twist kit includes:1x brush motor with freewheel1x Chain1x Customized sprocket & components1x Motor controller1x Mounting plate + bolts1x Twist throttleThe thumb kit includes:1x brush motor with freewheel1x Chain1x Customized sprocket & components1x Motor controller1x Mounting plate + bolts1x Wuxing thumb throttle