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;
- 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.
What are the sizes of bicycle wheels?
The geometric parameters of bicycles differ according to a strict pattern. this applies to the size of the frame and the diameters of the wheels. Let’s start with a size chart:
|Wheel, inches / mm||Rim, mm||a bike|
|20/508||406||Children’s, teenage, folding, BMX|
|24/609||507||Teenage, foldable adult|
|28/711||622||Road, hybrid, highway|
The first column presents the Traditional wheel diameters in inches and millimeters. The wheel is measured with the tire. To find out the size of the rim, you need to subtract the height of the tire, multiplied by two. Standard Rim Sizes Shown in the second column.
Bicycle wheel measurement systems:
- Classic, inches;
- In centimeters;
- ISO standard, in millimeters.
The International Organization for Standardization (ISO) has implemented a universal wheel measurement system to avoid confusion. All bicycle manufacturers adhere to it. The dimensions of the wheels are made up of the diameter of the “clean” rim and the width of the tire profile.
When choosing new tires, you need to know the rim landing diameters. these numbers for tires must correspond to them. This will come in handy when changing to a different tire profile. In everyday life, a wheel is measured in inches, and in inches it gives the dimensions more conveniently. And by the size of the wheel, you can also determine the type of bike. walking, mountain or road.
Wheel sizes are important to know when choosing a children’s bike. There is a direct relationship between the numerical values of the diameters with the height and age of the child, the so-called “wheel size”. Below is a table of standards:
|Diameter, inches||Height, cm||Age|
|12||up to 98||3|
|fourteen||98. 104||3. 5|
|14, 16||104. 110||4. 5|
|16, 18||110. 116||5. 6|
|20||116. 128||6. 8|
|24||up to 164||over 8|
Wheel sizes for children’s bicycles are separate from adults: children’s row ends at 24 “-wheels, while adults are just getting started (excluding 20-inch BMX). 24-inch wheels can be safely attributed to teenage and universal (for small adults). Of course, this data will only help you choose a bike, otherwise fitting is needed.
How to measure the diameter of a bicycle wheel
Sooner or later, the cyclist is faced with such a concept as wheel sizes. This may be during the purchase of the bike or the first time you replace the punctured tube and tire. How important is it to know the geometric parameters of the “running” bike? Nothing less than going over the bushing or lubricating the chain.
Determining the diameter of a bicycle wheel is very simple. We will talk about this in our article. Of course, this parameter, most likely, will be recognized precisely from the moment of purchase or in the process of “studying” their two-wheeled friend. Nevertheless, suddenly he is unknown for some reason, for example, they gave him a ride for a while, but here the tire was flat, and it is necessary to put a new camera.
Bicycle tire markings
And now a little about tires and their meanings. According to the classical system, the dimensions are applied in this order: wheel diameter in inches / tire profile width.
According to the international ISO system, the same parameters are stuffed onto rubber in the opposite order. first the profile height, then the rim landing diameter. Values are in millimeters. For the same tire or tube 20 / 1.75 in ISO it will look like this: 44.4 / 406.
The table below shows the ranges of the profile heights of tires for the rim landing diameters:
|Standard markings||Rim, mm|
|20 / 1.5. 2.125||406|
|24 / 1.5. 2.125||507|
|29 / 1.75. 2.35||622|
For one fit size, you can choose the Tires shown. However, it is better to take into account the recommendations of the bicycle manufacturer in the passport and adhere to the recommended parameters. Tires that are too narrow will puncture more often, while tires that are too high increase resistance to movement and can damage the sides. Each rim has its own tires. Optimal matching of tires to wheel sizes will allow you to ride longer, without punctures and damage.
The most important criterion, in our opinion, is the cyclist’s height. Recently, many manufacturers have switched to the so-called Size Split system, in which the size of the wheel depends on the size of the frame. frames from 14 to 18 inches have wheels of 27.5 inches, and frames from 17 to 23 to 29 inches. Thus, on the basis of this principle, if your height is no more than 175 cm, then you should pay attention to a bike with 27.5 inches wheels, but also DO NOT lose sight of the 17 frame 29er. Well, if your height is 180 or more, then we definitely recommend the twenty-ninth wheel!
The size of the wheels of the so-called “niners” (from the English “Twenty nine”. “Twenty nine”) came to us from the world of hybrid bicycles or cross-country (and to them. that’s road) bicycles. The diameter of the rim in all of them is the same. 700 mm, the only difference is in the width and increased strength of the rim in 29ers. Well, the 29-inch size is achieved by installing a wider and taller off-road tire.
Which wheel size to choose, 27.5 or 29 inches?
The exact answer. which is better and which is worse. cannot be given here. Everything is individual and depends on many factors, including the level and style of riding, the anthropometric data of the cyclist, etc. Consider the main selection criteria.
Wheel size 27.5 “or 650B came into the world of MTB from road cycling, more specifically, its kids department. For young riders, For whom 28-inch adults were too big, we made smaller rims, perhaps not 700, but 650 mm in diameter. Then this standard migrated to MTB.
What is the best bicycle wheel diameter, 27.5 “or 29” inches
Yes, in this article we will raise this issue, the reason for the heated debate on forums and holivars. What choice, in favor of what wheel size, should a person make, who opened the door to the world of MTB, or just decided to change their old 26er, for something more modern, meeting the increased needs and skills of the owner? First, let’s figure out where these wheel sizes came from.
Twenty-ninth wheels are less maneuverable than 27.5-inch wheels. If you rode 26 wheels before buying a niner, then you will need to get used to the unusual behavior of large wheels for you. To compensate for this effect, some bicycle manufacturers put handlebars slightly longer on niners than on bicycles with 27.5 wheels. this is obvious, because a larger wheel, which has a large gyroscopic effect, requires more lever to turn. Wheels 27.5 inches are devoid of this drawback and are close to the old 26 in terms of performance “standard.
Acceleration and roll forward.
27.5 wheels accelerate faster than 29 is a fact. If you need to break away sharply at the start. this 27.5 will help you with this, the niner will have to “spin” a little more time. But when a certain speed is reached, the twenty-ninth wheels still roll longer and this is especially noticeable at long distances.
Wheel angle of attack.
This is the angle that is formed when the wheel hits an obstacle. The difference in angle can be seen in the picture below.
There are 29 wheels here. the angle is smaller, respectively, the wheel will not slow down much, passing through the obstacle and the passage itself will be more comfortable for the cyclist. But 27.5 wheels will noticeably reduce the speed, up to a stop, if the angle of attack turns out to be very large. The same applies to pits and potholes. where the 29er will pass comfortably and without reducing speed, the 27.5 wheels can critically lose traction or what is called “stick” and stop completely!
The contact area of a bicycle wheel with a surface.
When passing difficult trails and routes, the grip of the tire to the surface means a lot. And if we discard the compound and tread pattern, and take into account only the diameter, then we get the following picture.
As you can see in the figure, the niner wheel has a larger contact patch, respectively, the stability and grip are better than in 26 and 27.5. This is of great importance when driving over rough terrain, forest paths teeming with roots and pebbles. in such conditions there is less chance. That the tire will come off the next wet spine, and the directional stability of the bike also increases.
Bicycle wheel size and features
As the season approaches, the streets are filled with cyclists. Kids on a bike with side wheels, their dads and moms on the mountain. The wheels are small, huge, wide and narrow. How not to get lost in this sea of spokes and sizes?
The easiest way to systematize this variety in a summary table of sizes:
|Wheel size (inches)||Rim size (mm)||types of bicycles|
And it immediately becomes clear what the size of the bicycle wheels depends on. For example, here’s the driver’s height or how the bike is positioned.
Relationship with growth
For very young cyclists, wheel and frame size is critical. While the baby is not very well oriented in space, the bicycle poses an increased danger to his health. Therefore, the wheels and frame are selected in such a way that the child’s leg freely lowered down reaches the ground. Hence the choice of small wheels. As for folding bicycles, the main requirement for them is small dimensions. A diameter of 20 inches is optimal for this.
As the child grows, so does the size of the bike. this is how teenage bicycles with 24-inch wheels appeared. And even after reaching an average height, you can select models with large wheels that allow you to ride comfortably and pick up, if necessary, High speed.
For leisurely walks, 26-inch wheels are good, this size is great for transporting a bike. Moreover, He does not take up much space. If speed is important, a 27 “size is more suitable. These rim dimensions are common on road bikes. You can also navigate which bike is suitable by the frame.
29 ” wheels are ideal for people with a height of 180 cm and above.
, clearly showing the difference between 26 and 29 wheels using the example of overcoming pits and obstacles:
Here are some figures for the most popular models, more precisely the size of the frames and their ratio to the height of the cyclist:
- Height 190 cm (and more). Highway 50-52, road 46-48, mountain 41-44.
- Height 180 cm. Highway 57-59, road. 56-58, mountain. 48-50.
- Height 170 cm. Road 53-55, road bikes 50-52 and mountain bikes 44-46.
So everything is interconnected. Rim diameter, frame size and rider height. Of course, these are NOT strict rules, but only a recommendation and hint when buying a bike. There are more accurate tables that take into account not only height, but also the length of the legs. However, this is more relevant for athletes performing tricks or setting speed records. The average two-wheeler will have enough of the above tips and the ability to adjust the height of the saddle and handlebars.
Maybe someone else will need to purchase a stem, but in any case, first you need to understand exactly what the bike will be bought for. For folding models, no one will wait for a perfect fit or speed characteristics, and almost all cruiser models are designed only for leisurely fashion shows along flat paths. Tires play a huge role in the “size” of wheels for a bicycle.
Models familiar to all with their characteristic frame shapes and dimensions acquire a completely different look with the configuration of tire dimensions. An example of this is the emergence of a fat bike. A regular bike, “changed” into wide tires, put on suitable rims, absolutely changed. Transformed Not only the appearance. Controls, acceleration dynamics and much more have been completely changed. So it is with standard wheel sizes. Suffice it to put “slicks” instead of aggressive rubber. Acceleration is noticeably easier and less effort is required to maintain a constant speed.