1.  Field of the Invention
The present invention relates generally to a foldable bicycle which can be easily moved in a folded state. 
2.  The Prior Arts
A conventional bicycle can be carried on a top of a vehicle or can be carried by a bicycle rack attached at a rear end of the vehicle.  However, the bicycle cannot be folded to reduce its size so that when the bicycle is stood on the top of the vehicle, it might be tangled by trees or tunnels.  The bicycle positioned on the bicycle rack affects a driver's ability to check the cars that follow the vehicle and the bicycles might drop from the bicycle rack.  Besides, when users want to carry the bicycle to take buses, certain equipments have to be equipped on hand or the bicycles cannot be entered into the buses. 
A foldable bicycle is developed so that the users can fold the bicycle and carry the folded bicycle to get on buses or any public transportation system.  Nevertheless, the folded bicycle is too heavy to conveniently carry for most of the users. 
The present invention intends to provide a foldable bicycle that includes an assistant wheel which can be cooperated with a front wheel and a rear wheel so that the users can easily move the folded bicycle.