揭秘自行车的轮胎尺寸（Bicycle tyre size）

揭秘自行车的轮胎尺寸（Bicycle tyre size） 揭秘自行车的轮胎尺寸(Bicycle tyre size) Bicycle tyre size With the 1/ tire size and rim size The size of a bicycle tyre is varied and confusing. To make matters worse, in the early stages, each country made bicycles in accordance with its own nominal system of dimensions. The nominal size of these different countries results in the fact that tyres of the same size have different digital indications in different countries. The most troublesome situation is that non identical tyres, which are not interchangeable, often have the same digital identification! 2/ traditional size system The traditional dimension system is based on the measurement of tire outer diameter. This is usually done in inches (26, 27, etc.), or in centimeters (650700, etc.). Unfortunately the development of tire and rim makes this method no longer meets the actual situation. For example, let us see why: 26 x 2.125 in late 30s is a heavy "balloon tyre (ballon tire)" the bicycle is the most popular size, today the size of the tire on the beach cruiser (beach cruiser) "is also common in the car. The actual diameter of this size is very close to 26 inches. Some riders, however, are not satisfied with the tyres. They want lighter, faster tires. So the industry to create a "medium" tire, its nominal size is 26 * 1.75, can be applied to the same rim. Although they are still known as "26 inches", the actual size of these tires is 25 5/8 inches rather than 26 inches. The same rim size were also adopted klunker pioneer west coast, and became the standard for mountain bike. In the market, you can find 25mm so narrow the tire rim, while the 26 inch tire its actual size is about 24 7/8. Second numbers or letters coded to indicate the width of the tire (26, x, 1.75, 27, x, 1, 1/4, 650B, 700C...) 3/ "0.75" is equal to "3/4"? Note that the inch system is nominal, sometimes in decimal indicating width (26 * 1.75), and sometimes expressed as fractions (26 * 1 3/4). This is the most common cause of mismatches. Although these sizes are mathematically equivalent, they are tyres of different sizes, both of which are interchangeable. I would like to make the following rules to summarize the features of tyre size, though it is a bit suspended: Brown rules for tyre size: If the dimensions of the two tires are mathematically equal, and one uses decimal and the other uses fractions, the two tires are not interchangeable. Sometimes tire manufacturers even on this muddled. Some European models, in particular, have been wrongly labeled. They should have used decimal, nominal, and incorrect fractions. 4/ size fraud Competitive stress often results in broadband measurement errors. The reasons are as follows: suppose you are looking for a high performance 700 * 25 tire in the market. If Pepsi and coca tire company tire company tire has the same quality and technology, but 70025 is actually 70024 fetal fetal Pepsi just nominal is 25, then the child will 70025 fetal Pepsi Coca Cola than real nominal lighter. In this way, PepsiCo Inc has a competitive advantage. The Coca Cola in order to avoid this kind of situation, they will even lighter 70023 logo for 70025. This situation was common in 70s and 80s, but later developed out of control, and then returned to the exact width Trends in measurement (but not very common). 5/ISO (E.T.R.T.O.) system: The ISO (International Organization for Standardization) has developed a universal tire size system to eliminate all kinds of troubles. This system was called "E.T.R.T.O" system, by the European tyre and Rim Technical Organization (European Tyre and Rim Technical Organization) set. The ISO system uses two digits. The first one is the tire or rim width in millimeters. (according to the actual broadband tire width changes a little. Rim width measurement is the distance between the edge of the rim). Second ISO digital is one of the key figures is the bottom of the wheel rim diameter, millimeter. Generally speaking, if the same number, can be mounted to the tire rim; if the number is different, is not to tire. For example, a highway tire 700 x 20C ISO nominal 20622; a mixture of the ISO tire 70038 nominal 38622. The width of the difference makes these tires are not suitable for used interchangeably, but any applicable one tire rim can be used together with other types of tire. Some of the conventional tire sizes in the United States are compared to their ISO wheel sizes. Fractional size: --------------------------------------------- Fractional system ISO 28, x, 1, 1/2.....635, mm 27, x, anything....630, mm 26, x 1 (650C)....571, mm 26, x, 1, 1/4... 597, mm 26, x, 1, 3/8 (S-6)....597, mm 26, x, 1, 3/8 (E.A.3)....590, mm 26, x, 1, 1/2 (650B).....584, mm 26, x 1 (650C).....571, mm 26 x 1 1/2 (F.12) 26 x 1 3/4 (S-7) 24, x 1.......520, mm 24, x, 1, 1/8....520, mm, or540, mm! 24, x, 1, 1/4....547, mm 24, x, 1, 3/8 (S-5).....547, mm 24, x, 1, 3/8 (E-5).....540, mm 20 x 1 1/8 20 x 1 1/4 20, x, 1, 3/8....451, mm 20, x, 1, 3/4....419, mm V17, x, 1, 1/4,... 369, mm 16, x, 1, 3/8.....349, mm 16, x, 1, 3/8.....337, mm 16, x, 1, 3/8.....335, mm 16, x, 1, 3/4.....317, mm 12, 1/2, x, anything....203, mm 10, x 2.......152, mm 8, x, 1, 1/4,... 137, mm --------------------------------------------- Traditionally, the fractional dimension of the rim is straight edge (staight-sided) on the rim. High performance sizes (571 mm /26x 1 & 630 mm /27) have been developed for the rims (hook-edged). Decimal size: --------------------------------------------- Decimal ISO 26 x 1, through 2.3... 559 mm 26, X 1.25 (rare)... 599, mm 26, X 1.375.......599, mm 24, x, 1.5-24, x, 2.125... 507, mm 22 x 1.75, 22 x 2.125... 457 mm 20, x, 1.5-20, x, 2.125... 406, mm 18, x 1.5...... 355, mm 18 x 1.75-18 x 2.125....355 mm 16 x 1.75-16 x 2.125....305 mm --------------------------------------------- Size of country: In the legal system, the first figure is nominal diameter, in units of millimeters. The letters followed indicate width: "A" stands for "narrow" and "D" stands for width. This letter is no longer with the tire width have a great relationship, because the narrow tire is often the tire rim width should be installed and do. For example, 700C was originally a wide tyre size, but now has a very narrow tire, the actual diameter of which is approximately 660mm. --------------------------------------------- Legal size ISO 700, C.....622, mm 700, D.....587, mm 650, A.....590, mm 650, B.....584, mm 650, C.....571, mm 600, A.....540, mm 550, A.....490, mm 500, A.....440, mm 450, A.....390, mm 400, A.....340, mm --------------------------------------------- ISO integrated reference: --------------------------------------------- ISO traditional nominal 635 mm..28 x 1 1/2 630 mm..27 x anything 622 mm..700 C 599 mm..26 x 1.25, X 1.375 597, mm..26, x, 1, 1/4, 26, x, 1, 3/8 (S-6) 590, mm..26, x 1, 3/8 (E.A.3), 650 A 587 mm..700 D 584 mm..650B, 26 x, 1 1/2 571, mm..26, x 1, 26 x, 1 1/2, 26 x, 1 3/4, 650 C 559, mm..26, x, 1.00-, x, 2.125 547, mm..24, x, 1, 1/4, 24, x, 1, 3/8 (S-5) 540, mm..24, x, 1, 1/8, 24, x, 1, 3/8 (E.5), 600 A 520 mm..24 x 1, 24 x 1 1/8 507, mm..24, x, 1.5-, x, 2.125 490 mm..550 A 457 mm..22 x 1.75; X 2.125 451 mm..20 x 1 1/8; x 1 1/4; x 1 3/8 440 mm..500 A 419 mm..20 x 1 3/4 406, mm..20, x, 1.5-, x, 2.125 390 mm..450 A 369 mm..17 x 1 1/4 355, mm..18, x, 1.5-, x, 2.125 349 mm..16 x 1 3/8 340 mm..400 A 337 mm..16 x 1 3/8 317 mm..16 x 1 3/4 305, mm..16, x, 1.75-, x, 2.125 203, mm..12, 1/2, X, anything. 152 mm..10 x 2 137 mm..8 x 1 1/4 --------------------------------------------- 6/ width considerations Although you can use any practice with the same hub diameter bottom "tire / Rim" combination, but the combination of too big difference is not wise. If in a wide rim with very narrow tires, there may be a risk of leakage and damage the rim. If you use the wide tires in the narrow rim, there may be a risk of failure or side ring rim. Unfortunately, today's mountain bikes are on the edge of this risk. In order to reduce the weight of the mountain bike rim is too narrow. This narrow ring fits well with the wide tire, unless the gas in the tire is full... But it loses the meaning of the wide tire and exerts undue pressure on the side ring. Georg Boeger offers a recommended width combination form: Safety, tire and rim [all diameter in millimeters. Away | tire width Away Rim width |18 2023252832353740 4447505457 13... |X. ..x...x...x................ 15. |. x...x...x...x............... 17. | motions x...x...x...x..x............... 19. |... x...x...x..x...x...x. 21. |. x..x...x...x..x..x......... 23. |.......... x...x..x..x......... 25. | x..x..x..x..x....................