自行车发展史 自行车简史

　　A modern bicycle by definition is a rider-powered vehicle with two wheels in tandem1), powered by the rider turning pedals2) that are connected to the rear wheel by a chain, and having handlebars for steering3) and a saddlelike seat for the rider. With that definition in mind, let’s look at the history of early bicycles that led up to the modern bicycle.
　　The Walking Machine
　　In 1817 Baron von Drais invented a walking machine that would help him get around the royal gardens faster: two same-size in-line wheels, the front one steerable, mounted in a frame which you straddled4). The device was propelled by pushing your feet against the ground, thus rolling yourself and the device forward in a sort of gliding walk. The machine became known as hobby horse. It was made entirely of wood. This enjoyed a short-lived popularity as a fad5), not being practical for transportation in any other place than a well maintained pathway such as in a park or garden.
　　The Velocipede6) or Boneshaker7)
　　The next appearance of a two-wheeled riding machine was in 1865, when pedals were applied directly to the front wheel. This machine was known as the velocipede, but was popularly known as the boneshaker, since it was also made entirely of wood, then later with metal tires8), and the combination of these with the cobblestone roads of the day made for an extremely uncomfortable ride. They also became a fad, and indoor riding academies, similar to roller rinks, could be found in large cities.
　　The High Wheel Bicycle
　　In 1870 the first all-metal machine appeared. (Previous to this metallurgy9) was not advanced enough to provide metal strong enough to make small, light parts out of.) The pedals were still attached directly to the front wheel with no freewheeling10) mechanism. Solid rubber tires and the long spokes11) of the large front wheel provided a much smoother ride than its predecessor. The front wheels became larger and larger as makers realized that the larger the wheel, the farther you could travel with one rotation12) of the pedals. You would purchase a wheel as large as your leg length would allow. This machine was the first one to be called a bicycle (two wheel). These bicycles enjoyed a great popularity among young men of means (they cost an average worker six month’s pay), with the hey-day being the decade of the 1880s.
　　Because the rider sat so high above the center of gravity, if the front wheel was stopped by a stone or rut in the road, or the sudden emergence of a dog, the entire apparatus13) rotated forward on its front axle, and the rider, with his legs trapped under the handlebars, was dropped unceremoniously14) on his head. Thus the term “taking a header” came into being.