To move down through the mountain it is important that you go down slowly, thus it becomes a necessity for mountain bikes to use heavy weight materials so as to reduce the speed of the vehicle.
2
基思·费尔奇称他的电动自行车是“擦山橡皮”,因为他可以骑车上班不洒一滴汗水。
Keith Felch calls his electric bike a "hill eraser" because he can ride it to work without breaking a sweat.