The full size of the bicycle wheel consists of diameter of the rim and thickness of the bicycle tire. Traditionally this parameter is measured by the English inch – today there are no more than six most widespread sizes of bicycle wheels - 20, 24, 26, 27, 28, 29 inches. As it is possible to learn its diameter for the bicycle?
Classification of the sizes
Diameter of the wheel at nurseries, folding and BMX bicycles is 20 inches, and at versions for freeride and similar extreme sports – 24 inches. At mountain, city and walking bicycles the size of the wheel is 26 inches whereas at highway types it reaches 27 inches. Road and hybrid versions and also traditional Soviet models have diameter in 28 inches. The new standard of wheels of mountain bicycles which gains the increasing popularity makes 29 inches.
The most widespread size of the modern bicycle wheel are 26 inches.
Tires with a diameter from 27 to 29 inches are established on the rim which size is 622 millimeters. Change of full diameter of the wheel happens only at the expense of thickness of bicycle tires. For its definition it is necessary to look at the size of tires which were established by bicycle earlier. Usually the standard size of bicycle tires is located on their sidewalls (as well as in automobile tires). Its size and landing diameter of the rim of the wheel have to correspond as much as possible each other.
Measurement of the size of the bicycle wheel
To learn parameters of wheels of the bicycle, it is necessary to measure diameter of the seat. For this purpose the thin soft wire or the steel tape which is located on the first ledge serving as the seat for the tire and is wound on its external surface before formation of completely closed ring is required. Then the film is accurately shot from the rim, stretch it in the straight line and measure the roulette its total length. The received figure is divided into 3.14 - it is and there is diameter of the wheel. The internal dimension of the tire can also be determined by subtraction from the outer diameter of double size of cross section of the tire. One more very exact way of measurement is drawing of the straight line on the horizontal plain surface. On this line it is necessary to pass one turn of the wheel, pressing on the wheel – at the same time on the tire the mark has to be in advance made (if desired it is possible to pass not one, and several turns). Then it is necessary just to measure the roulette the piece which was passed by the wheel. For obtaining the most exact result the trip can be repeated several times and to calculate the average value which is the size of the bicycle wheel.