The majority of Japanese electric bike are driven by shafts for two main reasons: First, Japan legally stipulates that electric bike must output auxiliary electric power according to manpower, so they must measure the pedal force and install a force measuring mechanism on the central axis (sensors, which combine the driving mechanism and the force measuring mechanism).
Second, Japan lacks the resource advantage of manufacturing high-efficiency disk motor. Compared with the domestic electric hub, some of the electric wheels made in Japan are inferior to each other in terms of shape size and weight (large appearance and heavy weight).
There is also a kind of friction transmission mode, that is, the power is transmitted by friction with the tire, which has the advantage of reducing the speed through the diameter ratio of electric bike conversion kit 20 inch wheel to the tire itself and omitting a deceleration mechanism. And directly driving the tire after the output of the motor.
But the weakness is also very obvious, the bicycle tire is out of circle or deformation is often, this situation directly affects the transmission efficiency and the reliability of the mechanism.
Therefore, thickened and widened special tyres and steel rings must be used to make them not easily deformed or round, so that daily maintenance and replacement of fittings are very inconvenient.