| 摘要 |
<p>Disclosed therein is an overdrive system for a four-wheel bicycle, which can get an increase in speed through combination of a plurality of sprockets and ratchet wheels, and which can drive with a small power when a user steps on a pedal of a drive lever using the principle of a lever as overdrive generating means. The overdrive system is very economic since it can load heavy goods thereon with small expenses or accommodate many people thereon, and allows the user to rapidly drive the bicycle with a small power through an organic combination of a plurality of sprockets and wheels using the principle of a lever.</p> |
