Abstract
A method and a system for automatically shifting gears of a bike are provided. In the method, a front servomotor is controlled to drive a front derailleur to a first gearwheel, and a rear servomotor is controlled to sequentially drive a rear derailleur from a first freewheel to a last freewheel, so as to measure a ratio of number of teeth of the first gear wheel to each freewheel. Then, the rear servomotor is controlled to drive the rear derailleur to the first freewheel, and the front servomotor is controlled to sequentially drive the front derailleur from the first gearwheel to the last gearwheel, so as to measure a ratio of number of teeth of the first freewheel to each gearwheel. The measured ratios of number of teeth are used to establish a relation table between the ratios and gears of the bike. Finally, a riding status of a user is detected to control the front and rear servomotor to drive the front and rear derailleur so as to switch to the gear adapted for the riding status.