brief introduction

Bicycles, also known as bicycles or bicycles, are usually small land vehicles with two wheels. It is generally driven by people riding on their feet and pedaling. Bi means two in English, and cycle means wheel. In Chinese mainland, Taiwan Province Province and Singapore, it is usually called "bicycle" or "bicycle", while in Hongkong and Macau, it is usually called "bicycle".

Many countries and regions think that bicycles are means of transportation, and they often need appropriate equipment, and even need to register their license plates with relevant government departments before they can get on the road. Some places require bicycles to use lights when driving at night. The Traffic Law of People's Republic of China (PRC) classifies bicycles as non-motor vehicles. In Hong Kong, bicycles are "non-motor vehicles" and do not need to be licensed, but when driving on the road, they must abide by the same traffic rules as motor vehicles.

history

1790 There was a Frenchman named Sifrak who loved to think. One day, he was walking in a street in Paris, because it rained the day before, and there was a lot of rain on the road, making it difficult to walk. Suddenly, a carriage rolled in from behind. The streets are narrow and the carriages are wide. Sifrak hid and hid. Fortunately, he was not hit by a car, but was splashed with mud and rain. When others saw it, they felt sorry for him. They were so angry that they wanted to stop the carriage and negotiate rationally. Sifrak murmured, "Stop shouting, stop shouting and let them go." The carriage has gone, and he is still standing on the side of the road. He is thinking: the road is so narrow and there are so many pedestrians. Why can't we change the structure of the carriage? We should cut the carriage in half and turn the four wheels into front wheels and rear wheels ... so he thought, go home and design. After repeated experiments, 179 1 built the first "wooden horse wheel" car. This car has two wooden wheels, a beam in the middle and a bench on it, like a toy. Because the car has no transmission chain, the car can move slowly by pedaling hard with the rider's foot. Moreover, there is no steering device on the car, so you can only go straight without turning. After going out for a while, you will be very tired and sweaty.

New things that have just appeared are always not so perfect. Sifrak was not discouraged, and he continued to look for ways to improve. Unfortunately, he died of illness soon.

In 18 18, a German ranger named delaisse walked from this forest in the east of the village to another forest in the west of the village every day. He thought: if people sit in the car, stop and go, do whatever they want, isn't it very chic? Delaisse began to make wooden trolleys, similar to those of Sifrak. But adding a handlebar to the front wheel to control the direction can change the forward direction. However, cyclists still have to pedal on the ground with both feet to push the car forward. When delaisse rode out to do experiments, he was laughed at by many people along the way. Nevertheless, he still likes this "cute little pony" created by himself.

1840, the British blacksmith Macmillan got a shabby "lovely pony". He installed a crank on the axle of the rear wheel, and then connected the crank with the front pedal with a connecting rod, and both the front and rear wheels were made of iron, with the front wheel being bigger and the rear wheel being smaller. When the cyclist steps on the pedal, the car will automatically move up and go forward. In this way, the rider's feet really leave the ground, and the alternating pedaling of the feet becomes the rolling of the wheels, which greatly improves the driving speed. 1842, Macmillan got on this car and ran 20 kilometers a day. Because of carelessness, he stepped on the car too fast and knocked down a little girl on the road, so he was caught by the police and fined. The charge is riding a bike savagely.

186 1 year, the French Michaux and his son were originally carriage mechanics, and they installed rotatable pedals on the front wheels; The seat of the car is mounted on the front wheel, so unless the riding skill is particularly superb, the handlebar will not be stable and will fall off. They dubbed this two-wheeled vehicle "bicycle" and exhibited it at the Paris Expo in 1867, which opened the eyes of the audience.

1869, after seeing French bicycles, Renault, England, felt that bicycles were too heavy and began to ponder how to make them lighter. He used steel spokes to tighten the rim as a wheel; At the same time, the frame adopts thin steel bars, and the front wheel of the car is big and the rear wheel is small. Thereby reducing the weight of the bicycle itself. From Sifrak to Renault, the five kinds of bicycles they made are very different from modern bicycles.

The real modern bicycle was born in 1874. This year, 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 the front wheel is still big and the rear wheel is small, which looks uncoordinated and unstable.

1886, British mechanical engineer stahly designed a new bicycle style from the perspective of mechanics and kinematics. Bicycles are equipped with front forks and brakes, and the front and rear wheels are the same size to maintain balance. The diamond-shaped frame is made of steel pipe, and rubber wheels are used 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 broad prospects for the mass production, popularization and application of bicycles, so he was called "the father of bicycles" by later generations. The bicycle model designed by stahly is basically the same as the current bicycle.

From 65438 to 0888, Irish veterinarian Dunlop got inspiration from treating flatulence in cattle. He glued the rubber hose used for watering in his garden into a circle, pumped it up, put it on the wheel of his bicycle, and went to participate in the bicycle race. He is the best among them, which aroused great interest. Pneumatic tire is an epoch-making initiative in the history of bicycle development, which increases the elasticity of bicycle and will not vibrate because of uneven road surface; At the same time, it greatly improves the driving speed and reduces the friction between the wheels and the road surface. This fundamentally changes the riding performance of the bicycle and improves the use function of the bicycle. Therefore, from the end of 18 to the beginning of the 20th century, it took about 200 years for the invention and improvement of bicycles, and many people struggled for it before it evolved into this riding mode.

The invention of bicycle

There are many stories about the invention of bicycles.

China was the first country in the world to invent bicycles. The ancestor of bicycle was a unicycle in China in more than 500 BC. During the Kangxi period of Qing Dynasty (1662 ~ 1722), Huang Lvzhuang once invented bicycles. "Grand View of unofficial history in Qing Dynasty" has been published for eleven years: "Huang Lvzhuang built a two-wheeled vehicle, which is more than three feet long and can sit for one person without pushing or pulling. When walking, turn your arm around the axis, then walk as before, and walk 80 miles around the sun with your arm. " This is the earliest bicycle in the world.

Bicycles were invented by western Europeans. In A.D. 1790, the Frenchman Sifrak developed a wooden bicycle without handlebars, pedals and chains. The car is shaped like a wooden horse, with two wheels nailed to its feet and fixed on a line. Because this bicycle has no driving device and steering device, and the seat cushion is low, Sifrak rides on the bicycle by himself, with his feet on the ground and pushing back hard to make the bicycle move straight forward. 18 17, Germany's von? Baron delaisse invented a handlebar that can move freely, making his bicycle easier to replace. Delaisse applied for a patent in Britain. 1839, a British worker k? Macmillan pioneered a pedal bicycle, which uses a crankshaft mechanism to drive the rear wheel, so that people can leave their feet off the ground when riding a bicycle. 186 1 year, one day, Michelson, a Parisian carriage and stroller manufacturer, repaired delaisse's bicycle. After the repair, they found it difficult to put their feet on the ramp, so they improved it, and installed a pedal crankshaft on the front wheel of the car, thus inventing Michelle's bicycle, which soon began mass production. In about 1870, Ma Zhi, a Frenchman, made a bicycle with a big front driving wheel and a small rear driven wheel, and the effect was very good. 1890, Humber Company of England produced a chain-driven bicycle, diamond bicycle, which has been in use ever since.

Bicycles were invented by Russians. 180 1 One day in September, Artamonov, a Russian serf, traveled 2,500 kilometers to Moscow to present a gift to Tsar Alexander I. The bicycle made by Artamonov was similar to that made by Sifrak in France. When Alexander I saw the bicycle made by Artamonov, he immediately ordered the abolition of his slave status.

Various design methods of early Europeans.

The first truly practical bicycle in the world appeared at the beginning of19th century. 18 17, German delaisse invented a wooden two-wheeled bicycle with handlebars in Paris. After the bicycle came out, it quickly became the favored means of transportation for Europeans at that time. In the19th century, some Europeans also conceived some ideal bicycle maps.

In the early days of bicycle invention, people thought that the bigger the wheel, the faster the speed. Two people are riding a bicycle, and the wheels are almost one person high.

In the invention stage of bicycle, some people did not design the two wheels of bicycle to be placed back and forth, but left and right. This bike is shaped a bit like a wheelchair.

This is a tricycle designed by early Europeans. The balance ability of tricycle is better, and it is easier for people to learn to ride tricycle. In the future, with the improvement of bicycle technology, tricycles gradually developed into a means of transportation for freight.

This is also a tricycle, but the designer put two power wheels in front and one auxiliary wheel in the back. People can also be front passengers when riding this kind of bicycle. This kind of bicycle is just the opposite of the modern bicycle design concept that people can be brought behind.

form

① Body part: including frame, front fork, handlebar, seat, front fork, etc. It is the main body of the bicycle.

② Transmission part: including pedal, crank, sprocket, chain, central shaft, flywheel, etc. The pedal is stepped by manpower, and the wheels are driven to rotate through the above transmission parts to drive forward.

③ Acting parts: front wheel and rear wheel, including front wheel and rear wheel axle parts, spokes, rims (rims), tires, etc.

④ Safety devices: including brakes (brakes), lights, bells and reflective devices.

Some accessories can be added as needed, such as brackets, clothes hangers, safety forks, fenders, air pumps, etc. In addition, sports cars, racing cars and mountain bikes equipped with speed change mechanisms are also equipped with speed change controllers and front and rear derailleurs.

classify

According to the purpose, it can be divided into trucks, ordinary cars, light vehicles, sports cars, competition cars, mountain bikes, special vehicles (such as fitness bikes and acrobatic cars).

According to different users, it can be divided into male cars, female cars and baby carriages.

According to the wheel diameter, it can be divided into 7 1 cm car, 66 cm car and 6 1 cm car.

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.

principle

Bicycle frame, tires, pedals, brakes, chains and other 25 components, the basic components are indispensable. Among them, the frame is the skeleton of the bicycle, which bears the largest weight of people and goods. According to the working characteristics of each component, it can be roughly divided into guiding system, driving system and braking system:

1. Guidance system: composed of handlebar, front fork, front axle and front wheel. The rider can change the driving direction and keep his body balanced by manipulating the handlebar.

2. Drive (transmission or walking) system: It consists of pedal, central shaft, sprocket, crank, chain, flywheel, rear axle and rear wheel. The pedaling force of people's feet is driven by pedals through crank, sprocket, chain, flywheel, rear axle and other parts, thus making the bicycle move forward continuously.

3. Brake system: composed of brake parts, the cyclist can control the brake at any time to slow down and stop the running bicycle and ensure the driving safety.

In addition, for safety and beauty, as well as from a practical point of view, it is also equipped with lights, brackets and other components.

ingredient

1. The frame component is the basic structure, skeleton and main body of a bicycle, and other components are directly or indirectly installed on the frame.

There are many structural forms of frame parts, but they can be roughly divided into two categories: men's frames and women's frames.

The frame is generally composed of ordinary carbon and copper pipes welded together. In order to reduce the weight of steel pipes and improve the strength, low alloy steel pipes are used in high-grade bicycles. In order to reduce the resistance of fast driving, some bicycles also use streamlined steel pipes.

Because the bicycle runs by the driving force and riding skills of the human body, the frame becomes an important structure to bear the impact load generated by the bicycle during running and whether it can carry the human body comfortably and safely. The manufacturing accuracy of frame components will directly affect the safety, stability and lightweight of vehicles. Generally, spokes have the same diameter. In order to reduce gravity, some spokes are made into variable diameter spokes with two big ends and a small middle, and some spokes are made into flat streamline to reduce air resistance.

2. Outer tires: There are two kinds of soft side tires and hard side tires. The cross section of the soft sidewall tire is wide, which can completely wrap the inner tube, and the landing area is relatively large, so it is suitable for driving on various roads. Hard-edged tires have the advantages of light weight, small landing area, small resistance and light driving.

The pattern on the tire is to increase the friction with the ground. Mountain bikes are especially wide in tire width and deep in pattern, and are also suitable for cross-country mountains.

3. Pedal assembly: The pedal assembly is assembled on the left and right cranks of the middle axle assembly, and is a device that converts horizontal force into rotational force. When a bicycle is riding, the pedal force is first transmitted to the pedal assembly, and then the pedal shaft drives the crank, the central shaft and the chain flywheel to rotate, so that the rear wheel rotates, thus making the bicycle move forward. Therefore, whether the structure and specifications of the pedal assembly are appropriate will directly affect whether the rider's foot position is appropriate and whether the bicycle can run smoothly.

Pedal: It can be divided into integral pedal and combined pedal. No matter what style of pedal, it must have a pedal surface, which is safe and reliable, has certain anti-skid performance, and can be made of rubber, plastic or metal materials. The pedal must turn flexibly.

4. Front fork assembly: The front fork assembly is located at the front of the bicycle structure, and its upper end is connected with the handlebar assembly, the frame assembly is matched with the front tube, and its lower end is matched with the front axle assembly to form the guiding system of the bicycle.

Turning the handlebar and the front fork can change the direction of the front wheel and play a guiding role in the bicycle. In addition, it can also play a role in controlling the operation of bicycles.

The front fork is a cantilever beam, so the front fork must have sufficient strength and other properties.

5. Chain: Chain, also known as cart chain and roller chain, is installed on the coupling wheel and flywheel. Its function is to transfer pedal force from crank and sprocket to flywheel and rear wheel to drive the bicycle forward.

Sprocket: made of high-strength steel to ensure the required tension.

6. Flywheel: The flywheel is fixed at the right end of the rear axle, has internal threads, keeps the same plane with the sprocket, and is connected with the sprocket through a chain to form the driving system of the bicycle. Structurally, it can be divided into two categories: single-stage flywheel and multi-stage flywheel.

Single-stage flywheel, also known as single sprocket flywheel, is mainly composed of jacket, flat block and core, jack, jack spring, washer, steel wire block and several steel balls.

The working principle of single-stage flywheel is that when the pedal steps forward, the chain drives the flywheel to rotate forward. At this time, the internal teeth of the flywheel and the jack are contained, and the rotating force of the flywheel is transmitted to the movement through the jack, and the movement drives the rear axle and the rear wheel to rotate, so that the bicycle can move forward.

When the pedal stops, the chain and the jacket do not rotate, but the rear wheel still drives the movement and the jack to rotate forward under the inertia. At this time, the internal teeth of the flywheel slide relatively, so that the movement is pressed into the notch of the movement, and the jack compresses the jack spring. When the tooth top of the jack slides to the inner tooth top of the flywheel, the compression of the jack spring is maximum. If it slides forward a little, the jack spring bounces to the tooth root and makes a "click" sound. The movement rotates faster, and the jack slides quickly on the inner teeth of each flywheel, making a "click" sound. Pedal in the opposite direction, and the jacket rotates in the opposite direction, which will accelerate the sliding of the jack and make the "click" sound more urgent. Multi-stage flywheel is an important part of bicycle transmission.

On the basis of single-stage flywheel, multi-stage flywheel adds several flywheel blades, which are combined with the sprocket on the central shaft to form various transmission ratios, thus changing the speed of bicycle.

① Impact strength of frame and front fork assembly: There are two methods to measure. Firstly, the drop impact test was carried out, the assembly was erected vertically, and a 22.5kg weight was placed above the front fork180 mm. Under the impact of a heavy hammer, the permanent deformation of the assembly can not exceed 40mm, and there is no visible crack; The second is the drop impact test, in which a weight of 70kg is placed on the saddle of the assembly, so that its center of gravity moves to the vertical position of the rear axle and falls forward freely. After repeated testing twice, no cracks can be seen with naked eyes. In addition, the frame and front fork need to be tested for transverse load strength, and their load weight varies with the vehicle type.

② Assembly firmness of handlebar and front fork: The measurement method is that after the handlebar is installed in the front fork, a torque of 25N·m is applied to the handlebar transverse tube (generally replaced by a test bar), and the handlebar is not allowed to rotate.

③ Strength of front and rear wheels: The measurement method is to clamp and lay the wheel with spokes flat, and apply a force of 178N in its transverse direction. After 65438 0 minutes, the permanent deformation shall not be greater than 65438 0.5mm. ..

(4) Braking performance of the brake car: The test methods are divided into two types according to the speed ratio of the vehicle. One is that the test speed of bicycles with a specified stroke of 5m or more is 24 km/h; The other is for cars with a journey of less than 5m, with speed 16 km/h and braking performance in dry state and wet state simulating rainy day. At the specified test speed, when the front and rear brakes are used at the same time, the dry and wet braking distances are not more than 5.5m and 15m respectively.

⑤ Safety device: The bicycle should be equipped with a bell or a lamp, and a reflector (commonly known as a reversing lamp). The reflector is illuminated by the headlights of motor vehicles or other external light sources, reflecting enough light to remind the other party to pay attention, thus protecting themselves. There are three kinds of reflectors: front reflector, side reflector and back reflector. The front is white, the back is red, the front wheel is white or amber, the rear wheel is white or red, and the pedals are white or amber.

Durability can be divided into internal and external aspects. The inherent durability requires a certain structural strength. Some parts that are easy to wear, such as bowls of front, middle and rear axles, teeth of flywheel, chain cores and rollers, and parts of foot brakes, all require heat treatment, carburization and quenching to improve the surface hardness. The durability of appearance is to prevent corrosion and improve appearance by electroplating and painting (painting). Electroplating is to plate copper, nickel, chromium or nickel, nickel, chromium on the original metal surfaces such as handlebars and rims. Other coatings can be selected according to the resource situation and antirust performance requirements. For some minor small parts, bright zinc plating process is adopted. Spray painting is to spray the surface of the frame and front fork by means of high voltage static electricity. The paint surface should be plump and gorgeous, and have certain antirust performance and paint film binding force.

Development Trend Due to the differences of living standards in different countries, the purpose of using bicycles is also different. In some countries, cyclists mainly use multi-speed vehicles, off-road vehicles and mountain bikes for travel, exercise and children's sports. Bicycles are the main means of transportation in some countries, and light vehicles and multi-speed vehicles are used more. Generally speaking, bicycles are developing in the direction of beauty, portability, firmness, novelty and cheapness. Beauty is beautiful in appearance, colorful, gorgeous but not vulgar; Light means light weight and light riding; High prison intensity; New models and varieties; Cheap means low cost and strong competitiveness.

maintain

Lubrication of bicycles

Bicycle is a large-scale and wide-ranging human machinery. The types of lubrication structures include sliding friction and rolling friction, small amount of friction and linear friction, fluid lubrication and boundary lubrication, oil lubrication and grease lubrication.

The key moving friction parts of bicycles are the center axle, front axle and rear axle, all of which are ball bearings and lubricated with No.2 calcium-based grease. During each overhaul, clean the ball, bead groove and cover, evenly apply No.2 calcium-based grease in the bead groove, and fill the special ball (bead) with smooth and complete surface and uniform particles around the shaft, and then cover it to avoid mixing dust and impurities. Then drop 2-5 drops of bicycle lubricating oil or low viscosity lubricating oil with viscosity of 7- 15mm2/s at 40℃ into the oil injection hole (with oil hole) or shaft end every quarter or half a year. But before refueling, the dust and dirt near the refueling hole or shaft end must be removed to avoid wear and tear. Generally, you can't mix lubricating oil when lubricating with grease, and you can't mix grease under normal circumstances. However, it is a special case on bicycles. In order to simplify the equipment, there is no butter nozzle, only lubricating oil is added to improve lubrication.

Secondly, the lubrication of chain and gear plate, here is the mixed friction of sliding friction and rolling friction, and most of them are in the state of boundary lubrication, so the friction conditions are harsh, so it is necessary to use lubricating oil with good adhesion and lubricity, especially most of them are open and work in dusty conditions, which has serious damage to chain and gear plate, so it is necessary to clean them at any time (every quarter or half a year) according to the situation, and switch to new oil, and most of them use high-viscosity lubricating oil (.

Normal riding use

Cleaning the car: cleaning the car can not only keep your car dazzling in the new time, but also avoid the corrosion of the frame. If you ride in heavy rain or mud, clean it as soon as possible after riding. Pay attention to the following points when washing the car: if there is not much sludge on the car body, or it is mostly dust, you can clean it with a rag or brush it with a big brush. Do not use high-pressure water column to clean the sludge on the car body. Although this method is very efficient, it may bring sewage into the bearing forcibly and cause damage to the bearing. In the case of a large amount of sludge on the car body, clean the sludge with a brush and soapy water, then rinse it with clear water and dry it with a cloth. Once the car is cleaned, remember to check whether the paint is peeling off. Steel frames will begin to rust after peeling off, while aluminum alloy or carbon fiber and titanium alloy frames will not rust, which will only affect the appearance. After washing the car with water, remember to dry the chain before oiling it.

Check the brake pads: remove impurities from the brake pads to ensure their braking force. If it is badly worn, it must be replaced.

Re-oil the conduit: If the braking or gear shifting action is not good, it may be that the friction between the inner and outer wires is too great. Remove the outer steel wire from the pipe stopper, coat the inner steel wire with butter, and then reinstall it. If the operation is still unsatisfactory after that, please consider replacing the inner and outer catheters.

Oiling the chain: After dripping lubricating oil on the chain, wipe off the oil on the outside of the chain after about ten minutes. As long as there is oil in the moving part on the inner side of the chain, the extra lubricating oil on the outer side will stick to dust, which will increase the trouble of cleaning, so it is best to wipe it clean. In addition, if you use spray tank oil, remember to wipe off the oil dripping to other parts after refueling.

Mid-term periodic maintenance

Check the chain: the chain will stretch after long-term use. The pitch of the chain is 0.5 inch. When measuring 24 chains, the length should be 12 inch. If the length exceeds the normal length 1/8 inches, replace the chain.

Cleaning the chain: If there is a lot of sludge on your chain, it may be time to clean it. You can use a chain washer to clean the chain, or you can remove the chain, find a container, fill it with solvent oil, put it in the chain, shake it and clean it, and finally take it out to dry and oil it.

Check the flywheel and the big toothed disc: if the flywheel has tooth jumping after the chain is updated, update the flywheel; If the teeth of the big toothed disc are seriously worn and the chain is stuck, it should also be replaced; Check the fixing screws of the big toothed disc; If it is loose, it must be locked again.

Check the rim: check whether there are slight cracks near the gas nozzle hole and the steel wire hole. If there is a crack, replace the rim as soon as possible, lift the wheel, turn the wheel, and observe whether the rim will rub against the brake pad. If so, please readjust the rim.

Check the steel wire: check whether the steel wire of the front and rear wheels is broken, and replace it if it is. After replacing the steel wire, the rim must be readjusted. When adjusting the rim, observe the direction of the rim deflection. If it leans to the right, loosen the right steel wire near the rim and lock it on the left, and vice versa. The left and right deflection amplitude of the rim should be less than 2mm.

Check the driver: check whether the driver is deformed in the car accident and whether there are cracks in the locking part of the elevator. If so, please update the driver.

Check the seat cushion and seat cushion rod: Remove the seat cushion rod and check for deformation or cracks. If not, put a thin layer of butter on it and put it back. Check whether the seat cushion is damaged and whether the bracket under it is intact. If there is any problem, please replace it.

Long-term regular maintenance

Check the wheel hub: remove the front and rear wheels, check whether there are cracks near the steel wire hole, and replace them immediately if there are any. Turn the hub shaft by hand to see, and then shake it up and down. If there is a gap, or it is loose, disassemble the hub shaft, clean up the oil inside, and then reinstall the new butter and the hub shaft. Remember to adjust the bearing to make the shaft rotate smoothly, but there will be no gap of shaking up and down.

Inspection center: Take off the chain, grab the crank and shake it left and right. If it shakes, lock the fixing screw. If it still shakes, adjust the center bearing. Put your ears on the seat cushion and turn the crank. The sound you hear should be "whirring" smoothly. If you hear abnormal sound or other strange sounds, it means that the bearing is damaged and the center should be replaced.

Check the pedal: remove the pedal, use an open-ended wrench of 15mm, and pay attention to the left pedal. Do not remove it wrongly. The pedal bearing does not need to be adjusted, but it still needs to be checked. If a box pedal is used, check whether its mechanism works normally and is lubricated. Check the transmission: check whether all moving parts of the transmission will shake. If so, the transmission is badly worn and should be replaced. Otherwise, lubricate the moving parts with oil.

Maintenance of shock absorber: Before hydraulic shock absorber, the wrist should be disassembled and replaced with new shock absorber oil. Check the egg yolk for cracks and deformation, and update it if there is any. The original purchaser should be consulted for the maintenance of the shock absorber.

Check the frame: check all the paint. If the frame is corroded to the point of perforation, it must be replaced. If the frame is deformed due to impact, it should also be replaced.

Update all internal and external conduits: All conduits have worn out after long-term use, so it is recommended to replace them to maintain their performance.

Field emergency repair

When riding a bike in the wild, the car broke down, which made you have to walk home. This is really a disappointing thing. So in order to avoid this situation, you must remember to bring tools when you go out to ride a bike. Don't think that accidents won't happen. It is always good to be prepared. The following describes the common faults and maintenance methods on site:

Flat tire: This is a frequent occurrence. When the tire has a puncture, remove the wheel, and use the tire removal tool to remove the outer tire and inner tube. If you have a spare tire, just install it directly. If you don't have a spare tire, you need to repair it. When mending a tire, first find out the hole, grind the hole slightly with sandpaper or rough things, then apply tire patching glue, and then stick it on when the tire patch is nearly half dry.

How to choose a bicycle?

Choosing a bicycle mainly depends on the frame, parts and assembly technology. Only by combining these three factors scientifically can a good bicycle be considered.

First, the framework:

1. What is the framework?

The frame is equivalent to a human skeleton, and only with the frame can various bicycle parts be mounted. The frame is made of iron, aluminum alloy and other materials, and the angle formed according to the length of the pipe affects the characteristics of the whole bicycle. For example, bicycles that ride well in a straight line, bicycles that turn easily, bicycles that ride comfortably, and so on. Many of these factors come from the framework.

2. What is a good framework?

Lightweight, firmness and good elasticity are one of the goals pursued by the frame. In order to achieve this goal, it depends on the technology of various frame manufacturers. For example, whether the designed frame is designed according to the strength and characteristics of materials and whether the welding process is mature. These directly affect the appearance, strength and elasticity of the frame. More importantly, painting. A good picture frame, painted evenly, sprayed with 3-4 layers of paint. Don't underestimate spray painting. Good painting can make bicycles easy to maintain and not easy to rust. If the car is loaded with a frame that does not meet the above requirements, it is possible to produce bicycles that cannot ride in a straight line or have difficulty turning, or bicycles that will be retired soon.

3. What material is the frame made of?

Iron frame is the most common, but iron frame is also divided into chromium-molybdenum steel, high-strength steel, ordinary steel and so on. After adding these other components, it can be made into, for example, thinner pipes, making the whole frame lighter. Recently, on the basis of not reducing the strength, a frame made of materials other than iron such as aluminum alloy has appeared. There is a frame made of titanium carbon fiber in cycling competition.