A gear shifting system (10)(10')(50) for lowering a motor rotational speed during gear shifting of a pedal-assisted bicycle, comprising: a power module (11); a micro-computer (21)(21')(61); a gear shift driver (31) and a vehicle speed sensor module (41); the micro-computer (21)(21')(61) having a motor rotational speed control logic (22)(22')(62)(62') and a vehicle speed/motor rotational speed correspondence table (24); during gear shifting, the micro-computer (21)(21')(61) executing the motor rotational speed control logic (22); a process of the micro-computer (21)(21')(61) executing the motor rotational speed control logic (22) including: finding a motor driven rotational speed corresponding to a current vehicle speed based on the vehicle speed/motor rotational speed correspondence table (24); controlling the mid-mounted motor (91) to be of a rotational speed lower than the motor driven rotational speed corresponding to the current vehicle speed but still maintaining a rotation of the mid-mounted motor (91);
