Useful Tips

Bicycle Wheel Diameter: Measurement Methods


Very often, bike owners are faced with the problem of determining the diameter or size of the wheels. This is necessary to buy a tire, disk or camera. Currently, there are several basic techniques for how to implement all this. Of course, repairing a bicycle if you have all the exact data you can implement without much difficulty. Sometimes the circumference of the rim or disk is required. All this can be found without any additional devices.

The convenience of the technology presented is that you do not need outside help. You need to start as follows.

• You need to fix the bike on a special stand. This is an added security.

• Using a tape measure, measure the distance from the floor to the center of the wheel axis. Divide the resulting number by 2.54. So we get the radius in inches.

• To measure a tire, that is, its width, simply use a tape measure to measure the distance across the tread.

It is worth noting that on most tires all technical information is applied. You just need to find the technical unit on the side of the tire. Most often, it is indicated as a combination of numbers 26 x 1.75 and so on.
ISO bus measurement

Currently, there is a special international system of estimates, which regulates standards. In this case, you need to make sure that your tire meets these requirements. The peculiarity of the technology is that all measurements are carried out in millimeters and the readings on the tire differ from those measured in inches. All measurements can be carried out in a similar way.

Recommendations and tips:

1. When making measurements, it is recommended to permanently fix the wheel so that there are no unnecessary rotations. This will have some effect on accuracy.

2. All data that is shown on the bus can be easily decrypted and the required tire options are also selected from them.

3. The tire diameter must be an exact number, so if you get tenths, it is recommended that you round them.
Adhering to these rules, you can easily determine all technical norms and standards. There are many tips in this segment that have helped many bike owners. Now you know how to determine the size of a bicycle wheel using the most common methods. It is very important to adhere to technical regulations and recommendations.

Wheel circumference calculation

The wheel circumference must be known in order to correctly set up the speedometer, which is often installed on bicycles. This indicator is also used when connecting navigation devices and an odometer. The problem is that if the indicators do not match, the speed on the speedometer will be completely different. Therefore, calibration is recommended.

Everything is done in a very easy way. You will need the resulting tire diameter just multiply by 3.14, and you will get the required figure. This is currently the most common formula that everyone uses. Of course, you can use the flexible tape measure the outside diameter of the tire. Each method gives accurate results.

You can also measure the length of the circumference using a lace, rounding the tire with it, and then measure the length using a ruler. All the nuances of interest have a certain meaning and you need to be more responsible about the presented activity. If you do the wrong measurements, then the wheel may simply not fit, and navigation devices will display incorrect information.

How to find the diameter of a bicycle wheel - a standard method

Finding out the size of a bicycle wheel is quite simple.

What is needed for this:

  • vehicle (bike),
  • calculator,
  • roulette.

First you need to determine the radius of the bicycle wheel. Only then will it be possible to determine the size. You can determine the radius using a special calculator or by the formula.

On the Internet, you can find all the basic formulas for determining the radius. We recommend using the following formula: D = 2 · r.

What sizes are bicycle wheels

In fact, all bicycles are designed taking into account a strict regularity, which allows us to judge whether a particular bike belongs to a particular group. Below is the size chart:

Wheel (in mm inches)

measured with tire

Rim (in mm)Bicycle
50820406Children's, folding road or BMX
60924507Teenage, Adult Folding
71128622Road, highway, hybrid
73629622Road, highway, hybrid

How to determine the size of the wheel on a bicycle: effective ways

This method is considered the simplest. To carry it out, it is necessary to fix the bike in a vertical position so that it does not accidentally fall, take a centimeter or tape measure, attach one of these devices to the axis of the sleeve and carry it to the very edge of the tire. Thus, you will get the radius in centimeters. To translate this value into inches, you need to multiply it by 2.54, and to find out the diameter - by 2.

This method is suitable for those who want to measure the diameter of not the entire wheel, but the rim minus the height of the tire profile. This may be necessary, for example, in order to put a tire different from the "native" profile, since several different types of tires can be selected for one landing diameter.

The radius is calculated based on the distance from the outer edge of the rim to the center of the sleeve. Multiplying this value by 200, we get the diameter in millimeters, which can be converted into inches.

This method involves measuring the diameter of the wheel of a bike through the circumference. To determine it, it is necessary to wrap the tire with a cable and make a mark at the junction with its beginning. Next, the cable must be straightened and using a ruler to measure the distance from the beginning of the cable to the left mark. This will be the circumference. If a fractional value comes out during measurements, then it must be rounded to the nearest whole.

Using these simple methods, you can easily measure the diameter of the wheel and translate the resulting value into any unit of measurement - inches, centimeters, millimeters.

So, the methods for determining the diameter of a bicycle wheel in inches and millimeters:

  1. The simplest and most reliable. On an old tiremounted on a bicycle its diameter should be written in inches or millimeters.

When choosing a new rubber, focus on it. If there is no tire with exactly the same marking, look at the interchangeability table and select the desired size in a different marking.

If a new tire is needed a little wider or narrower, check the tire width and rim width chart.

If in doubt, talk to the seller. He will tell you whether it is suitable for you both in terms of size, and in terms of tread, riding style and which roads you want to ride.

  • See if it’s written the rim size on it itself. Sometimes manufacturers write the size in the ETRTO system in mm: landing diameter and width. Depending on this, the size of the tire is selected. What dimensions in inches are suitable for your rim size in mm can be found in this table.
  • If nothing is written on the rim and, most importantly, the tire, you will have to calculate its diameter “manually”.

    This can be done by measuring the radius and multiplying it by two.

    For younger students reading this article, I recall that one diameter consists of two radii.

    Only need to measure strictly from the center of the sleeve, and not from its edges. When measuring, the bike should stand upright, and the tape measure, holding one end to the ground, keep the same strictly upright and not along the wheel spokes. Only such a measurement will give the correct value.

    In the same way, you can immediately measure the diameter of the wheel itself. The main thing is to accurately determine its upper cut. To do this, you can take a level and attach it to the top of the tire, and, holding it strictly horizontally, determine the desired size from the tape measure.

    After that, translate it from mm to inches. To do this, divide it by 25.4 (1 inch = 25.4 mm) and calculate the size in inches. The result can be rounded to standard inch wheel sizes.

    For example, if the result of the measurements is 720 mm, divide by 25.4 and get 28.346 inches. So, most likely, the actual size of the wheel, taking into account the accuracy of calculations, is 28 ”.

    In principle, the rim diameter can also be measured in the same way.

    Just pay attention to the difference between what is measured by the tape measure outside and the fit size of the rim.

    For those who are not looking for easy ways in life, you can calculate wheel diameter through its circumference. How to calculate the circumference of a bicycle wheel is described on our website in a separate article (Second method).

    And knowing it, it is easy to calculate the diameter. To do this, the circumference in millimeters must be divided by the number "Pi" (3.14). Having received the diameter in mm, divide it by 25.4 and get the diameter in inches. Similarly to the previous paragraph, the result will have to be rounded to the nearest integer in inches. The more accurate all measurements, the more accurate the result and less rounding.

    Wheel diameter

    The procedure is as follows:

    1. First you need to take measurements. In this case, the bike should stand upright. For measurements it is necessary to use a special measuring tape. Such a tape is applied from the center of the sleeve to the ground. Experts recommend measuring vertically. With this method of measurement, the probability of random error is reduced.
    2. After determining the radius, it is necessary to carry out calculations. To do this, you need a calculator. Radius must be multiplied by 2.
    3. After that, you need to convert inches to centimeters. This can be done using a calculator. The result should be divided by 2.54.

    Consider an example:

    • The radius of the wheels is 37 cm.
    • Now you need to multiply 37 by 2. Result: 74 cm.
    • After that, it is necessary to divide the obtained result (74) by 2.54. As a result, we get: 29.1. The final value needs to be rounded. In this case, the size of the bicycle wheel is 29 inches.

    Tire width

    You can independently determine the size of the tires on a two-wheeled horse. This will require roulette. It is advisable to use metal tape measure. Using it is very simple.

    You need to measure the distance from one edge to the other. Metal tape measure must be placed perpendicularly. Only in this case will the result be reliable.

    ISO diameter measurement

    What is an ISO? This is a universal marking of the organization. All manufacturers of bicycle wheels use this marking.

    ISO consists of two numbers:

    • tire width
    • rim diameter.

    The width of the tire can vary within wide limits. This parameter is not so important. First of all, pay attention to the rim diameter.

    How to measure the width of the wheel according to the ISO system:

    1. To measure the width of a bicycle wheel, you must use a standard metal tape measure. Metal roulette must be put on the tire (across the tread).
    2. If necessary, translate the result into millimeters. You can use various formulas for this.

    How to measure wheel diameter according to ISO system?

    • First you need to measure the distance from the rim to the bicycle wheel. For measurement, you can use a special tape.
    • The result should be multiplied by 2.
    • Then you need to translate the result into millimeters.

    Wheel circumference calculation

    What is the circumference. This is the most important parameter. There are several ways to determine this value. To do this, use a calculator and formulas.

    The circumference value is necessary for such purposes:

    • to configure the bike computer,
    • to properly set up a special odometer,
    • to adjust the speedometer.

    There are several ways to define this parameter:

    1. Apply paint to the tire tread (marking).
    2. Using a thread (lace).
    3. The calculation method.

    Using a lace

    To calculate the circumference, you can use various objects:

    Consider the procedure:

    1. Around the bicycle tire you need to pull the thread or lace.
    2. Now make a note. To do this, you can use a felt-tip pen or chalk. Marking must be done in the place where the lace is in contact with its beginning.
    3. After that, remove the thread (cord).
    4. Now you need to measure the distance from the mark to the end of the thread (lace). To do this, use a special tape measure or ruler.

    By calculation

    If you like math, then you will like this method. The circumference can be determined by the formula. But for this you need to know the diameter of the tire.

    If you know this parameter, then you can proceed with the calculations:

    1. The formula for the calculations: C = D · π. 3.14 is the number Pi.
    2. The tire diameter must be multiplied by the number Pi.
    3. Let's see an example: 28 × 3.14 = 87.92.


    This is a very affordable effective method. As a label, you can use paint or chalk.

    Consider the procedure:

    1. On a tire it is necessary to put a label (paint).
    2. After that, you need to draw a two-wheeled horse in a straight line. In this case, spots should remain on the asphalt. The first spot is the beginning of the path. The second spot is the end of the path.
    3. Now you need to measure the distance between these spots on the pavement.

    To buy a bicycle tire, you need to determine the diameter of the tire. You can find out the diameter of a bicycle wheel in different ways: length calculation, calculation method, tire measurement according to a special international system, classic method.