Abstract: An assistance system includes a resistance detecting unit obtaining a resistance factor, a database storing starting torque values and operating torque values, a torque calculation unit including a controller, and a torque-control handlebar grip operated to trigger an assigned gain and to tune the same to be provided to the torque calculation unit. When switched to an aided mode, the controller calculates a compensated torque value based on one of the starting/operating torque values and the resistance factor, calculates an output torque value by a product of the compensated torque value, the assist ratio and the assigned gain, and controls a torque motor to drive rotation of a driving wheel based on the output torque value.