Abstract: An electric motor-assisted bicycle includes a vehicle speed sensor to detect a vehicle speed, a torque sensor to detect a pedal force on a pedal connected to a crankshaft, a motor to generate an assist force that assists the pedal force, a motor controller to control the assist force by the motor depending on the pedal force and the vehicle speed, a threshold determiner to determine an unauthorized alteration determination threshold depending on the vehicle speed, and an unauthorized alteration detector to determine whether an unauthorized alteration has been made to the vehicle speed sensor or the torque sensor by comparing a running output and the unauthorized alteration determination threshold, wherein the running output is the sum of the assist force by the motor and the pedal force. If an unauthorized alteration has been made, a predetermined control is performed to address the unauthorized alteration.

Abstract: An electric motor-assisted bicycle includes a vehicle speed sensor to detect a vehicle speed, a torque sensor to detect a pedal force on a pedal connected to a crankshaft, a motor to generate an assist force that assists the pedal force, a motor controller to control the assist force by the motor depending on the pedal force and the vehicle speed, a threshold determiner to determine an unauthorized alteration determination threshold depending on the vehicle speed, and an unauthorized alteration detector to determine whether an unauthorized alteration has been made to the vehicle speed sensor or the torque sensor by comparing a running output and the unauthorized alteration determination threshold, wherein the running output is the sum of the assist force by the motor and the pedal force. If an unauthorized alteration has been made, a predetermined control is performed to address the unauthorized alteration.