Children's bikes have a good, moderate line design to ensure that the child will not affect the growth of body shape when riding. For example, the design of some manufacturers body imitates the sports bike, the body design is too long, let the child must bend down to ride, such will affect the child's spine development, make its walk also won't bend unconsciously. In the selection of materials, children bicycle try to choose high carbon steel and other relatively strong materials, because children learning to drive easy to fall, the strength of steel is easy to appear damage. Aluminum-magnesium alloy has good strength, but the body is too light, which is not suitable for children who are learning to ride bicycles. It is easy to cause danger due to too fast cycling speed.