If the size is too large, the child will not be able to hold the handbrake tightly when braking, and will not be able to brake the car. So it's best to take your kids along when shopping. In addition, the braking force shall not be less than 50N. Otherwise, the car will break down and bring harm to the children. Children's bicycles are also equipped with protective wheels (balance wheels), which can keep the rider balanced. Therefore, it is necessary to pay attention to whether the bicycle is properly equipped (one for each left and right) and not to dismantle it at will when using the bicycle. Parents should take this into consideration when choosing and using the bicycle.