The bike is a convenient and eco-friendly vehicle for going around. To promote its use and ease transportation, public bikes have been widely implemented by metropolitan governments, universities, and companies. The behind technique for these shared bike systems differs from one another. This study aims to propose a method for operating and monitoring public bikes within a predefined area. At the beginning, user locates and unlocks the bike via mobile application. Each bike is equipped with an electronic lock which supports GPS service and GPRS connection. When being used, the vehicle’s GPS data is regularly sent to the server. At the server-side, the Ray Casting algorithm is used to check whether the current location is inside the allowed area or not. If the current location is out-of-range, the server will notify the manager via email and trigger the bike’s buzzer. To return, user parks and manually locks the bike anywhere inside the allowed area. Besides, a website is built for administrator’s management. After testing, the electronic lock, mobile, and web application work properly for all functions.