20世纪可说是机动车的天下,它们占据大街小巷,动辄呼啸而过,留下废气和噪音,以及过度消耗能源的危机给当代和未来的人类。人类在使用机动车的百年后,环境污染与能源耗竭,成为21纪所必须面临的两大困境。近几年来,由于能源短缺,油价飙升,自行车以其便宜、轻巧、无污染和无噪音等优势,再度搏得人们青睐,加上其绿色环保和回归自然的概念,骑自行车更成为一种风雅时尚的运动。 Twentieth century can be said that the world of motor vehicles, they occupy the streets, frequently whistling, leaving the exhaust and noise, as well as excessive energy consumption crisis to present and future generations of mankind. Hundreds of years of human use of motor vehicles, environmental pollution and energy depletion, become the 21st century must face two plight. In recent years, due to energy shortages and soaring oil prices, bicycles have become popular again with their advantages of being cheaper, lighter, pollution-free and noise-free. Coupled with their concept of green environmental protection and return to nature, bicycles have become more elegant Fashionable sport.