Bicycle is a kind of land vehicle with at least two wheels driven by people's pedals, commonly known as free car, bicycle or bicycle. Bicycles are noise-free, pollution-free, light in weight, simple in structure, low in cost and convenient to use and maintain. They can be used not only as tools for walking and carrying things, but also for exercising, so they are widely used by people.
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 French Michaux and his son invented the big front wheel and the big rear wheel. ⒃ ⒃ ⒃ ⒃ ⒃ ⒃ ⒃ ⒃ ⒃ ⒃ ⒃ ⒃ ⒃ ⒃ ⒃ ⒃ ⒃ ⒃ ⒃ ⒃ ⒃ ⒃ ⒃ ⒃ ⒃ ⒃ ⒃ ⒃ ⒃ 934 ⒂? It was exhibited at the Paris Expo in 867, 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 adopt chain drive structure on bicycles, but at this time, bicycles were still big front wheels and big rear wheels R.
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 for entertainment, fitness and competition have high strength and wheel diameter. ⒙ザ ッ? Write panic disorder, panic filtering, and uncover the goal. Martyrdom? What happened? Naikui? What's the penalty for holding a boat? Contradictory? Ostrich? What happened? Hang up? Is the dam inclined? Fat enough to drink? Are you bald? What is worse than chaff? r
Second, the history of bicycle development
The horse was the first animal to be conquered by human beings. Once people set foot on its broad back, they can travel around the world in the most labor-saving and comfortable way. But the horse is one of the animals that need considerable skills to control, and people soon found that it is much easier and more labor-saving to let the horse pull it than to climb on the horse's back to control it, so there were wheels, so there were four-wheeled carriages. The carriage is indeed a great invention, but human wisdom naturally goes far beyond this. Thus, two wheels were born in human history-the Frenchman Sifrak was splashed with mud when he walked in the street on rainy days. This splash made him suddenly think: the carriage is so wide, it should be cut in half, and four wheels should become two wheels ... So, 586661
This car has two wooden wheels, a beam in the middle and a bench on it, like a toy. (as shown in figure 1) The new things that have just appeared are definitely not so perfect. This "wooden horse wheel" has neither a transmission chain nor a steering device, so it naturally needs to be improved.
At 18 18, it was also an accidental idea for a German ranger named delaisse. He also made a wooden cart, which looked very similar to Sifrak's. However, he added a handlebar to the front wheel to control the direction, which can change the direction of progress. But when riding a bike, you still have to use two pedals to push the car forward. At that time, when delaisse rode his "pony" on the road to test, he was laughed at by many people. The emergence of new things will always be ridiculed by traditional forces of one kind or another, but the inventor of mankind will never stop because of these ridicule. 1840, the British blacksmith Macmillan improved the pony invented by delaisse. He installed a crank on the axle of the rear wheel, and then connected the crank with the front pedal with a connecting rod. The front and rear wheels were made of iron. U?？ Huan Chu? Promise? Hey? Oxime? Say it? Hurt? What about Nomura? Hey? In 842, Macmillan rode this kind of car and ran 20 kilometers a day (as shown in Figure 2).
In 186 1 year, Messau and his son in France installed rotatable pedals on the front wheel, and the saddle of the car was installed on the front wheel. They dubbed the car "bicycle", and it appeared in the Paris Expo of 1867, which opened the eyes of the audience. (as shown in figure 3)
Later, the British Renault used steel spokes to tighten the rim as a wheel (see Figure 4).
From Sifrak to Renault, their bicycles are very different from modern bicycles. The real modern bicycle was born in 1874. Luo Song, an Englishman, ingeniously fitted his bicycle with chains and sprockets, and used the rotation of the rear wheels to propel the car forward. But it is still not coordinated and stable enough. (as shown in Figure 5) 1886, British mechanical engineer stahly designed a new bicycle style from the perspective of mechanics and kinematics, with a front fork and brakes, and the front and rear wheels are the same size to maintain balance. He made a diamond-shaped frame out of steel pipes and used rubber wheels for the first time. Stahly not only improved the structure of bicycles, but also transformed many machine tools for producing bicycle parts, which opened up a broad road for the mass production and popularization of bicycles, so he was called "the father of bicycles" by later generations. The bicycle model he designed is basically the same as today's bicycle (Figure 6).
Human wisdom is really everywhere. 1888, Irish veterinarian Dunlop was inspired by the treatment of cattle flatulence. He glued the rubber hose for watering his garden into a circle and put it on his bicycle, which was the beginning of pneumatic tires. Pneumatic tire is an epoch-making pioneering work in the history of bicycle development, which not only fundamentally changes the riding performance of bicycles, but also improves the use function of bicycles. From 179 1 to 1888, the invention and improvement of the bicycle, the ancestor of motorcycles, experienced the unremitting struggle of these inventors for nearly 100 years. We must be moved by human inventions.