现有的自行车和三轮车用脚蹬起来比较费劲 ,不适于幼儿玩 ,而电动车又价格太贵 ,一般家庭不愿买。因此可设计一种起坐式自行车 ,即 :将车的前后轮的车轴均设计成单向滑轮 ,只能向前转 ,不能向后转 ,前轮为单轮 ,后轮为双轮 ,也可前轮为双轮 ,后轮为单轮 ,车轮的前叉交汇在一个 Existing bicycles and tricycles pedal more strenuous, unsuitable for children to play, and electric cars and the price is too expensive, the average family do not want to buy. Therefore, a type of bicycle can be designed as a sitting bicycle. That is, the axles of the front and rear wheels of the car are designed as unidirectional pulleys, which can only be turned forwards and can not be turned backward. The front wheels are single wheels and the rear wheels are double wheels. The front wheels can be double wheels, the rear wheels are single wheels, and the front fork of wheels meets at one