## ISO

The measurements will require the same materials.

- Wheel diameter

The distance from the center of the**wheel**to the outer edge of the rim is measured. Multiplications are performed in the same way as in the first case. The difference is only in units. According to the international standard, the value of the radius is indicated in millimeters. Therefore, the resulting diameter in cm is translated into years. 1 cm = 10 mm. For example, D = 50.8 cm, this number is multiplied by 10 and you get 508 mm. - Wheel width

Measurement is carried out in the same way as in the standard method: the tape is placed across the tread pattern. The result obtained is reduced to the accepted unit of measurement in the ISO system. to millimeters.

[Attention type = yellow] Tip! The correct choice of the type of tires will depend on their service life. When using the rubber recommended by the manufacturer (or values close to the specified), it will last longer. So narrow tires are suitable for walking on a flat road, and wide ones. off-road. [/ Attention]

## Standard measurement method

To determine the diameter, you first need to know the radius of the wheel. Knowing the latter, you can calculate the diameter. According to the mathematical formula, the diameter of a circle is equal to two radii: D = 2 r.

## How to measure the diameter of a bicycle wheel?

When you need to replace a punctured tire or purchase a spare tire, it is important to know the diameter of the bicycle wheel. The marking can be viewed on the currently installed bus. It is printed on the side of the tires, and indicates its diameter and width. If the numbers are erased or the inscription is NOT legible, you can measure the diameter of a bicycle wheel yourself using two simple methods.

- Tire marking
- Standard measurement method
- Wheel diameter
- Tire width
- ISO
- Wheel circumference
- With an inelastic lace
- By calculation
- By labeling

## Tire marking

The classical system of standards involves marking the tire in this order: the first number indicates the diameter of the tire, the second indicates the width. The standard units of measure are inches. For example, the entry 29×2.00 reports that the tire diameter is 29 “(or 73.66 cm) and the width is 2.00” (or 5.08 cm).

It should be remembered that the marking of bicycle tires according to the international ISO standard has a different form and unit of measurement. millimeters. So, first the value of the wheel width is applied to the rubber, and then the diameter. For example, the inscription 40×700 means that the tire has a width (width) of 40 mm, and its diameter (diameter) is 700 mm.

## Wheel circumference

This value is no less important than the previous ones. After replacing an old or damaged **bicycle** tire with a new one, you need to adjust the exact operation of the devices (speedometer, odometer, navigator). For this, the size of the circumference of the wheel is entered into the cycling computer.

You can find out this parameter in several ways.

### By calculation

The required value can be calculated using the formula, knowing the diameter of the tire. The diameter can be indicated on the tire itself or determined by the previously described method. The circumference of the wheel is equal to the product of its diameter by the number Pi: C = D π. Measurement unit inches.

For example, 20×3.14 = 62.8 “, where 20 is the diameter of the tire in inches and 3.14 is the pi number (constant).

### Tire width

Measurement, as in the above case, is made with a tape measure. It is placed perpendicularly on the tire and the distance from one edge to the other is measured. The tape should be kept strictly horizontally (that is, across the bike tire) so that the result is as reliable as possible.

The width of a **bicycle** tire purchased to replace a damaged one may slightly differ from the original one (be slightly wider or slightly narrower). This fact will not affect the ability to install it.

**Wheel** diameter

The measurement is carried out as follows: the measuring tape is applied from the ground to the center of the sleeve on the wheel axis. This will be the radius of the wheel. Since the bushing is an order of magnitude wider than the wheel, to reduce the error, the measurement should be carried out strictly vertically. The tape should not go along the spokes of the measured wheel.

Next, the found radius in cm is multiplied by 2. The calculated number is the wheel diameter. To convert units of measurement (Centimeters) to inches, the product result must be divided by 2.54 (1 “= 2.54 cm). For example, the Found distance is 34.2 cm. Multiply this number by 2, divide by 2.54 and get 26.929.

If the calculation results in a NOT an integer, the total is rounded to the accepted standard wheel sizes in inches. In the description of the case, the wheel diameter will be 27 “. Adult bicycles often have wheel sizes between 26 and 29 “.

[Attention type = green] Tip! When taking measurements, it is better to use a wooden ruler or a rigid metal tape measure. The elastic tape can stretch and distort the result. [/ Attention]

### With an inelastic lace

To do this, pull a string, cord or cable around the bike tire. Its thickness does not matter, the main thing is that it fits snugly against the rubber. Next, you need to make notes at the place of its contact with the Initial end. Then remove the cord, spread it on the ground and using a ruler (tape measure) measure the distance from the starting end to the set mark.

### Tire measurement using the ISO method

1. Find out if your tires are NOT ISO measured instead of the conventional method. The ISO system uses millimeters to determine the dimensions of a bicycle wheel. If you do not have a tape measure to measure a wheel in inches, just know that there are 25.4 millimeters in one inch and use a calculator to multiply the width by 25.4.

2. Make sure the bike is placed against a wall or on a stand. Measure in millimeters from the center of the wheel to the inner edge of the tire. Twice the resulting number to calculate the diameter. Most ISO-measured tires for adults are 650 to 700 millimeters in diameter.

3. Measure the tire width in millimeters. Use the recommendations above for tread measurement. Remember that tires of different widths can be used on the same bike if the difference is NOT too drastic.

4. When buying a new ISO-measured tire, remember that width comes first, followed by diameter. For example, a 53.3 x 700 bicycle wheel has a tread 53.3 mm wide and 700 mm in diameter along the inner edge of the tire.

## How to measure a bicycle wheel

- Measure the tire in the usual way;
- Tire measurement by ISO method;
- Calculating the circumference of a bicycle wheel

To purchase a spare bicycle tire, you must first determine the size of the wheel. In fact, measuring a wheel is a common procedure during bicycle maintenance.

There are two ways to measure a bicycle wheel, including determining the size of the tire and rim, and both are simple to perform. Sometimes it is necessary to know the circumference of the wheel, which is also not difficult and can be done in several ways.

### Measuring the tire in the usual way

1. Stand your bike upright, leaning it against a wall or on a stand. When the bike is straight upright. It doesn’t lean on you and it’s easier to measure its wheel. If you are measuring the wheel alone, it is better to use a metal tape **measure**, rather than a plastic one, as in this case you can do it with one hand.

2. Measure the distance in inches from the ground to the center of the wheel. So you measure the radius of the wheel or half the diameter. Multiply this length by two to calculate the tire diameter. Except for BMX models, most adult bicycle wheels are 26 to 29 inches in diameter.

3. **Measure** the distance from one side of the tread to the other. This number is the tread width. It can vary a lot, depending on the destination. Usually, the wider the tread, the higher the cross-country ability, while the narrower tread is used for smooth and fast driving.

4. When buying a new tire, remember that in traditional standard sizes, diameter comes first, then width. For example, a 26 x 1.75 tire will have a 26 “diameter and 1.75” tread width.

### Calculating the circumference of a bicycle wheel

1. **Measure** the circumference, or distance, along the outer edge of the bicycle wheel, in order to more accurately adjust the speedometer, odometer, GPS or bike computer. If you recently purchased a cyclometer or you need to adjust an existing one because you have installed tires with a different tread size, you need to determine the wheel circumference.

2. It is easy to calculate the circumference by multiplying the tire diameter by pi. The circumference can be quickly determined if you already know the outer diameter of the tire. Since Pi is 3.14, the circumference of a 26 “tire can be obtained by multiplying 26 by 3.14, which is 81.64”. If you already know the tire diameter and tread width, the circumference can be found on the Internet.

3. Measuring the circumference with a rope. If you do not know the diameter of the wheel, you can measure the circumference by gently running a thread around the outer edge of the tire. Mark or cut the thread where it reaches the starting point and measure its length to determine the tire circumference.

4. Place a dot of paint on the tire tread. Carefully roll the bikes in a straight line so that the wheel makes two turns and the paint marks are visible on the ground twice. Measure the distance from one spot to another to determine the circumference.

### With an inelastic lace

To do this, pull a thread, cord or cable around the bike tire. Its thickness does not matter, the main thing is that it fits snugly against the rubber. Next, you need to make notes at the place of its contact with the Initial end. Then remove the cord, spread it on the ground and using a ruler (tape measure) measure the distance from the starting end to the set mark.

## Methods for measuring wheel diameter

The very essence of the measurement comes down to obtaining numerical data. centimeters, millimeters or inches. Can be done in Several methods:

- Measurement radius;
- ISO;
- Through the circumference.

The easiest is the first way. We take a centimeter or tape measure and place the bike vertically so that it does not fall. Attach a zero straight edge to the hub axis and draw it into the tire edges. This will be the radius of the wheel in centimeters. Then we multiply by two. we get the diameter. To get millimeters, you need to multiply by 10, and inches by 2.54.

ISO will measure the diameter and rim and height of the tire profile. This method may be necessary if you need to put a tire of the second profile. several types of tires can be selected for the same rim diameter.

Only measure the distance from the center of the hub to the outer edge of the rim. Knowing the radius, it multiplies it by 200. we get the diameter in millimeters. And I pick up another tire on it.

The third method shows how to determine the diameter in terms of the circumference. For THESE purposes you will need a rope and a tape **measure**. We wrap the tire with a cable, make a mark at the junction with the beginning of the cable. Straighten and use a ruler to measure the distance from the beginning of the cable to the mark. This will be the circumference.

- Staple paint on tires.
- Place the wheel so that the mark is in the lowest position.
- Will ride one turn.
- At the bottom, the paint will be erased from the tire, and on the sides it will remain, you can understand that the wheel was rolled exactly the opposite.
- Measure the length of the filled line.

Do not be afraid that for large wheels this value will exceed 200 cm. First, divide it by 3.14. we get the diameter in centimeters. And then divide by 2.54 to convert to inches. Actually, it’s so easy to find out what size the wheel of a bicycle is.

When measured with a ruler, you will most likely get fractional values, for example, 28.23 inches. Round to whole values taking into account the existing diameters.

## Dimensions of bicycle wheels. Relationships between wheel diameter and driving characteristics

Consider some options for how the size of a bicycle wheel can affect driving.

- The larger the wheel of the bicycle, the more effort and energy it takes to spin it. Therefore, you will have to train your endurance and pump up your legs. But at the same time, the achieved rotational speed will be much higher and better than in the case of a lower.
- Large wheels are more convenient to use on smooth and level roads. A 29 “size would work well here. If we are talking about a bike for mountain walks with frequent stops, then giving preference to smaller rims. for example, 26.
- As for the width of the tire, here the passability on difficult areas. for example, stones or rocks. depends on its width. If you are choosing wheels for just such a case, then giving preference to small models with a minimum width of 2
**inches**.

Table. Bicycle wheel diameter

Rim diameter in inches | Rim diameter in mm | Matching bikes |

20 | 406 | Kids models, BMX |

24 | 507 | Old Soviet bikes like Salyut or Altair, teenage bicycles, bicycles for extreme sports |

26 | 559 | The most common size option, which is often used on standard mountain bikes or city bikes |

27 | 622 | Road bikes |

28 | 622 | Old Soviet model bicycles like Ukraine or folding Aist, as well as hybrid and road bicycles |

29 | 622 | One of the latest developments in the field of cycling. Can be used for both advanced mountain bike models and everyday riding |

The smallest wheel size The most advantageous especially for children with their small stature

The fact is that in the process of a child’s development, it is necessary to pay attention to how the bicycle affects his posture, whether it is comfortable when driving. A prerequisite is the following: when stopping, the baby’s leg must absolutely freely reach the ground

This feature is provided only by a rim with a diameter of 20 inches.

Models designed for teenagers often wear wheels with a diameter of 24 inches. This is NOT an adult option, but NOT a toddler size either. Although the requirement remains the same. The designers made sure that all parameters related to health were met.

The remaining 3 sizes are tailored for medium to tall adults. You can also focus on the model and purpose of your bike. But, for example, for people whose height exceeds 180 cm, it is recommended to use only wheels with a diameter of 29 inches, since they will meet the requirements of the characteristics of the body of tall people.

It is worth noting that if you are focusing on height when choosing a bike and its parts, then you should observe Not only the size of the wheel, but also the size of the bike frame, and in some cases, use the stem in addition to create the most comfortable driving conditions. Some experts recommend taking into account, in addition to growth, the length of the legs, because it is they who get tired the most during the movement and need careful care.

## Motorcycle tire markings

On the tire of any motorcycle, you can find a lot of all kinds of information, even the date and country of manufacture. Motorcycle tire markings are different from bicycle tires. To determine the size of the wheel, you need to find approximately the following set of numbers: 180/55 ZR 17 (73W) TL. The first value shows the width of the tire in millimeters, the second shows the height as a percentage of the width. Next are the design, disc size in **inches**, load and speed indices. In motorcycle tires, the profile width does not have the same width. The 55% shown is based on the widest wall spacing. In this example, the wheel size is the sum of the rim size (17 **inches**, approximately 432 mm) and the tire height (55% of 180 = 99 mm), we get 531 mm.

## Which option is better to choose?

If there is no controversy about the smallest wheel sizes, then it really boils about rims with a diameter of 26 and 29 inches. This is one of the most popular sizes, but in essence there are quite visible differences between them, knowing which you can easily choose the option for your bike and body.

- Bikes with 29-inch tires pick up the required speed easily enough, handle well, just get over obstacles, handle turns freely. But in comparison with a diameter of 26 inches, such a bicycle, on average, picks up speed only with a large expenditure of energy, so it takes more time to circle.
- 26 inch wheels are more agile in action, pick up speed much faster and stop easier. But as for inertia, here the rim with a diameter of 29 inches takes the palm.
- If you are looking for the option to tackle various bumps, then 29-inch wheels are your option. Since they have a large area of contact with the surface, you will overcome bumps without even noticing them. Also, driving up a steep incline will give you much less inconvenience if the rim size is larger. Accordingly, on a bicycle with a wheel diameter of 26 inches, you will need more energy and strength to overcome obstacles.

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

The simplest and most reliable. On old tires

, mounted on a bicycle, its diameter must be written

in inches or millimeters.

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

If a new tire is needed a little wider or narrower. check with.

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

See if the rim size is written on it

. Sometimes manufacturers write the size in the ETRTO system in mm: landing diameter and. 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.

If nothing is written on the rim and, most importantly, the tire, then 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 remind you that one diameter consists of two radii.

Only you need to measure strictly from the center of the sleeve, and not from its edges. We measure, the bike should stand vertically, and the tape measure, putting one end to the ground, keep the same strictly vertically, and not along the spokes of the wheel

. 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 using a tape measure.

After that, we 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 measurement results in 720 mm, divide by 25.4 to get 28.346 inches

This means, most likely, the real size of the wheel, taking into account the accuracy of the calculations, is 28 “.

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

Just pay attention to the difference between what is measured with a tape measure on the outside and the landing size of the rim.

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

And knowing it, it is easy to calculate the diameter

For this, the circumference in millimeters must be divided by the number “Pi” (3.14). Given the diameter in mm, divide it by 25.4 to get the diameter in inches. Similar to the previous paragraph, the result will have to be rounded to the nearest whole number in inches. The more accurate all measurements are, the more accurate the result and less rounding.

Many people while cycling rather than attach much importance to self-service transportation. Questions such as changing sprockets, lacing or repairing a tire are quite difficult in action, and there is a desire to learn a little more about the Iron Horse, and sometimes completely assemble a bicycle with your own hands. The latter option will allow you to make transport as convenient as possible, ride comfortable and take into account all individual characteristics.

### By calculation

The required value can be calculated using the formula, knowing the diameter of the tire. The diameter can be indicated on the tire itself or determined by the previously described method. The circumference of the wheel is equal to the product of its diameter by the number Pi: C = D π. Measurement unit inches.

For example, 20×3.14 = 62.8 “, where 20 is the diameter of the tire in inches and 3.14 is the pi number (constant).

### Tire width

Measurement, as in the above case, is made with a tape **measure**. It is placed perpendicularly on the tire and the distance from one edge to the other is measured. The tape should be kept strictly horizontally (that is, across the bike tire) so that the result is as reliable as possible.

The width of a bicycle tire purchased to replace a damaged one may slightly differ from the original one (be slightly wider or slightly narrower). This fact will not affect the ability to install it.

## How to choose a bicycle wheel size

Sooner or later you will have to determine the size of the bicycle wheels: whether it is the purchase of an “iron horse” or the first replacement of a punctured tire. The dimensions of the bicycle wheels are adjusted for the person’s height and for the future use of the **bicycle**. Manufacturers annually produce bicycles with seven basic **wheel** sizes:

- 20 inches. Models for children or compact bicycles consisting of 99MX use these wheels.
- 24 inches. The size of the bicycle wheels is suitable for teenagers. They are also models for performing tricks. Previously, such wheels were installed on Soviet bicycles. “Firework”.
- 26 inches. The most common and popular size: standard mountain and walking models. This diameter is sometimes put on “pseudogirski” chinese bicycles for teenagers.
- 27
**inches**. Medium road models. Classic Cycling Tour de France. - 27.5 inches. Extreme mountain bikes.
- 28 inches. Hybrid models. Such diameters were preserved on legendary bicycles “Ukraine”.
- 29 inches. Mountain and hybrid bikes. The new standard for mountain models. Perfect for people with a height of 180 cm
- 36 inches. An innovation in the cycling world. This tire size allows you to tackle difficult terrain (stones, mud) and guarantees better grip.

Choosing a bike model usually involves comparing the wheel sizes of two popular wheel sizes: 26 “and 29”. Marketers to popularize 29-inch hybrids stated that a larger wheel diameter makes the bike more stable and provides better ride. In fact, these parameters are more dependent on the cyclist than on “iron horse”.

Bicycle wheel diameter, frame size and height data are the secret formula for choosing a bike. Knowing only your height, you can choose a bike frame. Main dimensions:

- Size S (16 “frame). Height 150-165;
- Size M (18 “frame). Height 167-178
- Size L (20 ” Frame). Height 178-185.

## Diameter definition and various markings

Changing wheels on a bicycle must be accompanied by calibration. To correctly calibrate the speedometer, odometer and especially the navigator, you need an accurate wheel diameter value.

Before you know the size of a bicycle wheel, pay attention to two simple rules:

- When measuring, the wheel should not rotate;
- It is advisable to round the measurement value to whole numbers.

It is easier to measure the diameter of a bicycle wheel by measuring the radius. We apply the ruler along the edge of the tire on one side and to the axis of the hub on the other. The resulting figure. Wheel radius. To find out the diameter of a bicycle wheel, multiply the radius by two. To get the results in inches, multiply the value in centimeters by 2.54. If the tire size is measured in inches, the marking is: diameter, then width.

Wheels “iron horse” can be measured in ISO system as well. In this case, the centimeters measured in the same way are multiplied by 10 to get the value in millimeters. ISO marking: width first, then diameter.

To determine the diameter of a **bicycle** wheel in a circle, you need a centimeter and a cable. We wrap the tire with a cable around the perimeter and make a mark at the junction. We unwind the cable and measure the length with a centimeter, and it will be the diameter in centimeters.

There is another practical way to determine the size of a bicycle wheel. It is necessary to put a drop of paint on the protector of the cover and drive the bike in a straight path. Two points from the paint will remain on the asphalt, the distance between them will be the circumference of the wheel.