Bicycles, also known as bicycles or bicycles, are usually small land vehicles with two wheels. After riding the car, it is a green and environmentally friendly vehicle driven by stepping on the pedal. In Mainland China, Taiwan and Singapore, they are often referred to as "bicycles" or "bicycles"; In Hong Kong and Macao, it is usually called "bicycle" (in fact, it is usually called in Cantonese); In Japan, it is called "self transfer". There are many kinds of bicycles, including single-person bicycles, double-person bicycles and multi-person bicycles.

Frame is the soul of bicycle. A good bicycle frame must meet the three conditions of light weight, sufficient strength and high rigidity. As a kind of bicycle sport, the lighter the weight is, the better, so the more labor-saving and faster you can ride; Enough strength means that the frame will not break or bend under high strength riding; High rigidity means that the frame should be rigid enough. Sometimes a frame with poor rigidity may not have safety concerns, but the transmission of the frame force is poor when riding, which makes the rider feel heavy when treading on it. Even if the frame is light and strong enough, but the rigidity is poor, it is still an unqualified sports bike.