The present invention is composed of propellers and gear transmission system. While a bicycler pedals a chain wheel, he also treadles a driving cylindrical gear, thereby a small driven gear wheel fixed on the bisector of the included angle between the seat tube and the down tube is driven, and then a pair of bevel gear is driven. Through driving an oblique shaft and gear, the kinetic energy is transmitted to the level shafts located in front of and in rear of the top tube, thereby the propellers located in the front of and in rear of the level shafts are driven respectively. By the speed-changing principle of gear system, the propellers are able to rotate at high speed. The bicycle will run quickly by means of the said propellers. |