18 18, Dries invented a wooden two-wheeled bicycle with handlebars, which runs with two pedals. 1839, Macmillan, Scotland, made the first iron bicycle with the rear wheel driven by a crank-link mechanism, which ran with pedals. 186 1 year, the Frenchman Michelle and his son invented a bicycle with a big front wheel and a small rear wheel. The front wheel was equipped with a crank and a rotatable pedal, and it was exhibited at the Paris Expo in 1867, which once set off a bicycle craze.
1869, British Renault used spokes to tighten the rim for the first time, made the frame with steel pipes, and installed solid rubber belts on the rim for the first time, greatly reducing the weight of bicycles. 1874, British Lawson began to use chain transmission structure on bicycles, but at this time, the front wheels of bicycles were still large and the rear wheels were small.
1886, stahly, England installed brakes on bicycles, used roller bearings, and narrowed the front wheels to make the front and rear wheels the same size, and formed a diamond frame with steel pipes; 1888, British Deng Lupu Company successfully applied pneumatic tires to bicycles, which significantly improved the riding performance of bicycles.
During the period of 1925, the world output of bicycles reached 2 million, of which Britain accounted for 50%, becoming the main exporter at that time. Since then, bicycles have been widely developed and their structures have been improved and perfected. After the Second World War, the automobile industry developed at a high speed, and bicycle production was affected. However, in the 1970s, due to the energy crisis, bicycle craze appeared again in the world, and bicycle production developed rapidly. By the 1980s, the world's bicycle production had exceeded 80 million, and China, Japan, the United States and Western Europe had become the world's bicycle production centers.
1884, The Scenery of Jiang Shen published by China recorded the appearance of cycling in China for the first time. 1897, China began to import bicycles from Britain; During the period of 1937, the Japanese successively set up bicycle factories in China, Shanghai, Tianjin and Shenyang, but the output was very small. 1949, the annual output of bicycles in China is only10.5 million; By the 1980s, there were more than 60 bicycle factories and 1000 bicycle parts factories in China, which basically formed a complete production system.
There are many kinds of bicycles, which can be classified according to different methods, such as trucks, ordinary cars, light vehicles, sports cars and racing cars. According to users, it can be divided into male cars, female cars and baby carriages; According to the wheel diameter, it can be divided into 28-inch cars, 27-inch cars and 26-inch cars. According to the material of main components such as frame, it can be divided into carbon steel car, alloy steel car and aluminum alloy car. According to the structure of the frame, it can be divided into rod stacker, detachable trolley and integral trolley. In addition, there are characteristic bicycles such as tandem bicycles, fitness bicycles and acrobatic bicycles.
Bicycle is mainly composed of body part, transmission part, moving part and safety device, and some accessories can be added as needed. The four main parts can be divided into frame, front fork, front fork, handlebar, front axle, central axle, rear axle, crank sprocket, pedal, flywheel, wheel (including rim, tire and spokes), chain, seat, brake, lamp, bell and reflector. Sports cars and racing cars equipped with transmission mechanisms are also equipped with transmission controllers, front derailleurs and rear derailleurs. Bicycle accessories include hangers, brackets, air pumps, safety forks, fenders, etc.
The car body is mainly composed of frame, front fork, handlebar, seat and front fork. Main parameters of bicycle: center distance between front and rear wheels, inclination angle of front fork and protruding distance of front fork.
The frame is a rhombic truss structure formed by brazing ordinary carbon steel pipes. The frame has enough strength to bear the weight of passengers and goods, as well as the impact force from the ground. The front fork is connected with the frame through a front fork assembly with an upper group and a lower group of ball bearings, and the front fork can flexibly rotate on the frame; The handlebar is fixed in the main pipe of the front fork by tightening the mandrel with the wedge nut in the center of the handlebar, so that it is connected with the front fork to form a rigid steering mechanism, providing good handling performance; The saddle is rigidly connected with the frame through the saddle tube, and bears all the weight of the human body. The height of the saddle can be adjusted according to the needs of the rider.
The transmission part consists of pedal, crank, sprocket, central shaft, chain and flywheel. The cyclist's foot steps on the pedal to drive the crank to rotate, and the sprocket is transmitted to the flywheel of the rear axle through the chain to drive the wheel to rotate. Generally, the transmission ratio of bicycles is fixed, that is, the stroke is a fixed value. More advanced bicycles and bicycles with special needs are equipped with different types of variable speed transmission mechanisms. There are three common types: central shaft transmission, transmission chain transmission and rear axle transmission.
The moving part consists of front wheel and rear wheel, usually consisting of front wheel and rear wheel axle, spoke rim and tire. The weight of the wheel and the pattern, specification and quality of the tire all affect the portability and comfort of riding; The weight of rims and tires are generally reduced as much as possible to make riding light; The lamp rim is made of aluminum alloy, and the rim is connected with the front and rear axles through spokes.
Safety devices mainly refer to brakes, that is, automobile brakes, followed by lighting equipment and horn devices. Braking is an important device to ensure the personal safety of cyclists. There are many kinds of brakes, which are basically divided into rim brakes and axle brakes. Rim brake is a mechanism that directly presses the brake shoe with high friction coefficient on the tire or rim through mechanical lever, push rod, pull rod or steel wire rope, so as to stop the wheel. Axle brake is a mechanism to stop axle housing in various ways. This kind of brake is not affected by improper rim, and the braking process is soft and smooth.
Lighting and reflective devices are important devices for safe driving of bicycles at night. The lighting device uses battery or generator to illuminate the road ahead for the rider, which has certain lighting brightness requirements; The reflecting device is a protective device. When it is illuminated by the headlights of other motor vehicles, it can reflect the light and remind the other party to pay attention.
Bicycles are developing in the direction of being light (light in weight and riding light), new (many varieties, new in color, detachable and foldable), strong (high in strength) and cheap. The shape and appearance of bicycles should be further refined, beautiful, colorful and harmonious.
For example, cross-country bicycles used for entertainment, physical exercise and competition have high strength, small wheel diameter, thick tire section, large teeth and claws on the tread and good off-road performance, which has become a favorite sporting goods for teenagers; Mountain bikes used by adults for outdoor travel are used in a wider range of conditions, so they are required to be lighter, more durable and equipped with speed change devices. Expressway racing is developing in the direction of streamlining and lightweight.