Abstract: A method and a device for measuring a tangential reaction force of a resistance device on a flywheel, and the reaction force multiply the radius of the flywheel to obtain a torque, such that the torque multiply a gear ratio is the torque to overcome the resistance of flywheel on the drivetrain. The torque to overcome the resistance of flywheel on the drivetrain adding a torque to overcome the inertia of the flywheel and mechanical friction under the state of no resistance is the total torque presented on the drivetrain. Such that using the total torque to calculate power and energy consumption.