This product organically integrates battery, motor, sensor, control and other electric unit components in the rear wheel assembly of the bicycle to form a complete power system, and adds intelligent functions to realize the interaction of the Internet of Things. Ordinary bicycles only need to replace the original rear wheel set with this product, and then they can be transformed into electric moped. When people are riding, the built-in sensor of the product can realize the assistance of the vehicle according to the users' riding speed and the power change of the pedal output. And people can use the supporting APP to achieve riding data recording, gear adjustment, performance detection and other functions with the mobile phone. The axle adopts quick-release design, which can realize the tool-free quick installation of this product.