Abstract: A method for quickly shifting the gear of an engine of a motorcycle having a gear assembly provided with a rotary member for selecting the gear, provides for detecting the position of such rotary member during the gear shift and with the gear engaged, identify the electrical signals detected by a special sensor functionally associated with such rotary member and relating to such position, detecting a predefined electrical signal value between the identified electrical signals and shifting the gear when such predefined signal value is achieved following an action of the rider on a gear lever. Furthermore, disclosed is the system for implementing such method.