Why do the older generation always ride bicycles and slide two steps before getting on the bus?

This is how variable-speed bicycles started in the last hundred years before their popularization. Because the old bicycle has a large tooth plate and a large tooth ratio, it is very laborious to start at zero speed. Starting at zero speed for a long time is a basic taboo in riding health knowledge-"stepping on heavy teeth", which is easy to damage your knees for a long time. Therefore, the cart is easy to start, and running forward on the car does not hurt the knee.