US Patent 10919602 Portable motor assembly

The present invention relates to a portable motor assembly comprising a case, a control module disposed in the case, a motor wrapped up with a friction wheel for connecting to the case and controlled by the control module for rotation, a fixing base connecting to a bottom of the case and having a clamp for fixing to a seat tube of a bicycle and at least one tension spring for pulling down the fixing base and making the friction wheel surrounding the motor tightly press against a surface of a rear wheel of the bicycle to drive a rear wheel of the bicycle.