Abstract
The invention provides an automatic gear shift method and system of a bicycle. According to the method, a front servo motor is controlled to push a front derailleur to first gears of a large toothed disc, a rear servo motor is controlled to push a rear derailleur to last flywheels in sequence from first flywheels of a rear toothed disc to measure the tooth quantity ratio of the first gears to allthe flywheels; then, the rear servo motor is controlled to push the rear derailleur to first flywheels of the rear toothed disc, and the front servo motor is controlled to push the front derailleur tolast gears from the first gears of the large toothed disc to measure the tooth quantity ratio of the first flywheels to all the gears; then, the measured tooth quantity ratios are utilized to build arelation table of the tooth quantity ratios and bicycle gears; finally, the riding state of a user is detected, and according to the relation table, the front servo motor and the rear servo motor arecontrolled to push the front derailleur and the rear derailleur to switch to the gear suitable for the riding state. By means of the automatic gear shift method and system of the bicycle, the tooth quantity ratios of all combinations of the front gears and the rear gears can be calculated, and the suitable gear can be automatically switched to according to the riding state of the user.