Bicycle

A bicycle comprising:

• a saddle;
• front and rear wheels;
• a body frame which fixedly supports said saddle and rotatably supports said rear and front wheels to transmit a driving force to said front wheel by pedaling a pedal by foot;
• a large gear which can be rotated integrally with said rear wheel and is provided concentrically with said rear wheel about a rear wheel axle, and includes a diameter smaller than that of said rear wheel;
• a small gear which is provided so as to circumscribe said large gear at a level above the rear wheel axle;
• a small gear support bracket which is provided so as to swing about said rear wheel axle, and rotatably supports said small gear at its upper end, and includes a load receiving surface at its lower end;
• a load transmission unit which is downwardly movably supported on said body frame and downwardly movable by a downward load and adjustably movable in a longitudinal direction of the bicycle on said load receiving surface;
• a first sprocket which is provided concentrically with said small gear so as to be rotatable integrally with said small gear;
• a second sprocket which is rotatably provided rearwardly of said first sprocket and at a level lower than a rotation center of said first sprocket;
• a chain which is wound between said first and second sprockets to transmit a rotation force between said first and second sprockets;
• and
• a first rachet which is mounted on said small gear so as to restrict rearward rotation of said rear wheel via said large gear,
• whereby a driving force can be transmitted to said rear wheel only by pedaling said pedal with said first rachet being disengaged from said small gear, while a physical burden on the legs of a rider can be reduced by engaging said first rachet with said small gear to utilize the downward load, in accordance with a longitudinal position of said load transmission unit relative to said load receiving surface, in a case where the bicycle climbs an uphill slope.