Bicycle tyres are divided into outer tubes and inner tubes. The specification of the outer tire is expressed by multiplying the outer diameter of the tire by the section size. So the 26 and 28 bicycles we usually refer to are the size of the outer diameter of the tires.
Generally, people only pay attention to the size of the outer tire when buying bicycle tires. It is not clear how the structure of the outer tire is related to its quality.
(1) The selection of outer tire The bicycle outer tire consists of five parts, namely the tire crown, the tire side, the tire ear, the cord layer and the tire toe (steel wire).
The tyre crown is generally required to be about 3.5mm thick. Due to its direct contact with the ground, special attention should be paid to the tread pattern of the tire crown. The tread pattern of the tire crown directly affects the service life of the tire. The tire crown pattern is divided into common pattern, off-road pattern and mixed pattern. Common patterns are suitable for large and medium-sized cities and flat dirt roads; The off-road pattern is suitable for rugged mountain roads, construction sites and mining areas; The mixed pattern is between the two. The requirements for pattern shall be neat and uniform, with bright surface, without cracks and aging.
The sidewall is the two sides of the outer tire, with a thickness of 1~2mm. It is required that the tire lug of the soft side tire and the steel wire of the hard side tire shall be free of deformation, crack, bending, depression and missing wrist, and firmly enter the part of the groove on both sides of the rim.
Its function is to bear strength and load. The cord layer is divided into cotton cord, rayon cord, synthetic fiber cord and steel cord, and the strength of these cords increases in turn. The cord is required to be free from bending, thin seams and sundries, and the inner tire and cord are firmly bonded without falling off. You can decide what kind of tire to buy according to the use conditions of your bicycle. It should also be noted that the strength of the ply increases with the increase of yarn count.
The tyre toe covers the inner tube and plays a part of protecting the inner tube.
The outer tire made of steel cord is called steel tire, also called hard edge tire. The advantages of this kind of tire are good fixation, good cushioning performance and portability. However, due to the thin tread, it is suitable for urban use. The hard edge tire shall also be free of deformation, crack, bending, depression and lack of rubber.
Hook-edge outer tire is suitable for light bicycles with wide section, small wheel diameter and low internal pressure. It is light in weight, good in cushioning, comfortable to ride and easy to load and unload.
Soft band, also known as band tire. Its feature is that it will not separate from the rim after air leakage, and its disadvantage is poor impact.
(2) The selection of inner tube In addition to the model, the relationship between the color and quality of the inner tube should also be understood. The inner tube has two colors: black and red. The quality of black is better because the black inner tube is processed with butyl synthetic rubber raw material. The strength of black tire is about 30% higher than that of red tire. In the black inner tube, it is divided into pure rubber inner tube and artificial rubber inner tube. The quality of the two black inner tubes is better than that of the synthetic ones. The heat resistance and wear resistance of this inner tube are far better than that of pure rubber inner tube, and it is not easy to burst. Even if there is a small leak, it also has a certain tightening and self-sealing effect. It is an ideal bicycle inner tube. So when you buy a black inner tube, you must find out whether it is natural rubber or synthetic rubber. In addition, it also depends on whether the inner tube surface is smooth and tidy, with uniform gloss, without bubbles, defects and cracks. The inner tube with good quality has good elasticity, uniform rubber thickness and good air tightness. You can shrink the inner tube tightly, press the air nozzle tightly with your hand, and then release the inner tube. If the inner wall still sticks tightly, it means that the inner tube is of good quality.