| 摘要 |
PROBLEM TO BE SOLVED: To enhance the foot attachment when the rider's foot is to be set on a road surface. SOLUTION: A bicycle 1 is structured so that a down frame 4 is extended down aslant backward from a head pipe 3 which bears a front fork 8 in such a way as capable of steering to the left and right and is equipped with a body frame 2 in which a seat frame 5 is installed as rising from the tail of the down frame 4, wherein a human power drive system and an assisting power drive system are furnished parallel, and the rear wheel 13 is driven by the human power applied to the human power drive system and an aux. power applied in compliance with the supplied human power. A power unit 15 to emit the resultant of the human power and aux. power is installed under the down frame 4, and a crank shaft 19c with crank arm 19b connected to its two ends is installed in a position down ahead of a bottom bracket 40 of the down frame 4 and seat frame 5 and behind the front wheel 9, and the length of the crank arm 19b is set so that the rotating locus A of a pedal 19a attached to the tip of the crank arm 19b is positioned ahead of the front extremity C of a saddle 12. |
