How many atmospheres are there in a bicycle wheel 26


Each tire has special markings with which you can determine the size, type of production material, direction, as well as the degree of inflation of the wheels (which is relevant for the case under consideration). Below is a table where you can find out what is the recommended pressure depending on the weight of the cyclist.

Seasonal changes

Seasonal adjustments are quite serious, mainly related to mountain bikes. In the summer, you should slightly underestimate the pumping and not rest on the maximum. Hot asphalt also heats up the air inside the chamber, which increases the volume and therefore the pressure. Also, a pumped tire wears out very quickly.

In winter, you should sometimes slightly exceed the maximum in order to achieve maximum work from the tread, especially if the rubber is selected with spikes.

How to check the pressure after inflation

The exact value can only be checked with a pressure gauge. Therefore, you need a pump with a pressure gauge or a separate electronic bicycle pressure gauge. You can go to a car service to check the pressure and pump up the wheels. But before pumping up your bike with a car pump, think about it. After all, the auto repairman may not pay attention to the pressure and ruin your tires.

Experienced cyclists can measure pressure by eye. You can inflate tires with a pressure gauge, memorize the value and squeeze the tire with your fingers. Remember the feeling, so you learn to understand how inflated your wheels are.

Standard pressure

Here are some tables that will help you navigate in difficult situations, namely:

  • an unknown tire without markings was purchased;
  • no physical access to the bike;
  • the marking is incomprehensible, the numbers are marked in unknown units.
Cyclist weight (Kg) Pressure (BAR) Pressure (Psi)
fifty 2.38-2.59 35-38
63 2.52-2.72 37-40
77 2.72-2.93 40-43
91 2.86-3.06 42-45
105 3.06-3.27 45-48
118 3.2-3.4 47-50

For a road bike, the pressure should be much higher, and typically ranges between 6.5. 9 atmospheres (up to 130 Psi), up to the maximum indicated by the manufacturer.

Theoretical knowledge

If the wheels are over-inflated, the bike will roll well, but the tire will not absorb at all on uneven surfaces. All difficult sections will be much harder, since the contact patch of the tire with the ground will have a minimum area, and you will be skidded around the bends. Needless to say, when cycling in winter, the situation is exacerbated by the slippery surface. In addition, pumping can cause the wheel to explode. Old Soviet cameras are especially susceptible to this, the material of which is already turning into dust from old age. The tire does not break due to excessive pressure immediately, but for example on a hill, where a pebble falls under the wheel. This situation is dangerous because sometimes literally rips the tire off the wheel.

The air pressure in the tires of a bicycle also affects the permeability of the wheel. Pumped rubber easily picks up all the carnations and glass on the road.

If the tires are flat, then the situation is no better than with inflated wheels. The tire does not sit tightly on the rim, it can slip off the wheel, and when driving onto the curb, a puncture can form (the so-called snake bite). The roll of the bike decreases and more and more force is required to pedal. However, when choosing between an under-inflated tire and an under-inflated tire, it is better to opt for an under-inflated tire. But we must not forget about reasonable limits. If the tire drags like a rag, then you are clearly mistaken with the pressure.

What to pump up

It is best to get a high pressure pump with a pressure gauge for your bike. So you will be sure of the choice of the size and will not overdo it.

Such a pump has adapters for inflating tires. But this process will take longer as it is designed for small shock absorbers. But the waiting time is worth it, because you will be able to adjust the pressure to within Bar.

Another useful feature of this pump is an overpressure relief valve. If you missed the desired value, you can press the valve and the excess air will come out.

Now let’s move on to the riding style.

I drive on relatively flat asphalt roads, country and forest dirt roads and paths, I like to drive fast. For this style of riding, I prefer to pump the wheels up to 3.5-4 atmospheres. Such a high bar value allows you to achieve good speed characteristics, high rolling, but when it hits bumps and stones, the fifth point immediately feels all the unevenness of the road surface.

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For those who like walking at low speed on the flat roads of parks, 2.5-3 atmospheres will be enough. On the Internet, you can often find recommendations to pump 2-2.5 bar into wheels, this is justified only for tires at least 2 inches wide and subject to driving over rough terrain or poor coverage. Low pressure increases traction and comfort, but reduces roll on flat pavement. You should not ride at a pressure less than 2 atmospheres under any circumstances.

The choice of the terrain, on which you prefer to ride, obliges you to choose a certain type of tire, but in general, if you have a universal tread, you can make your ride comfortable on a particular type of road surface by changing the amount of atmospheres on the wheels. The figures below are based on a standard 2-2.1 ″ tire.

For gravel, mud, grass, sandy surface, it is better to pump up to 2.5 atmospheres, which increases the adhesion of the tread to the ground and allows the wheel to smooth out all the irregularities of the road surface well enough.

For flat asphalt tracks, feel free to use a pressure of 3 bar or more. However, there is one but. If you have a fairly bald tread (wheels with a weak relief or slick tires), and you are driving at high speed on wet or even wet asphalt, then you risk slipping (flying out) when cornering. If it rains on the road, just slow down or slightly deflate the tires.

In this article, I described the most acceptable criteria for choosing tire pressure, but since each person independently selects the most convenient pressure values, I advise, first of all, when mastering a bicycle, experiment.

Acceptable level marking

The level of optimal inflation of bicycle tires, in addition to external conditions, depends on the size and design of the bicycle rubber itself, the rubber used, the manufacturing technology and is regulated by the bicycle tire manufacturer. Information about the range of permissible pressures is applied by the manufacturer to the outer surface of the tire to the right of the brand designation (logo) below the marking of the size of bicycle rubber. For example, the marking 35. 65 PSI indicates that the permissible pumping range of the cameras should lie within 35.0 65.0 PSI.

What is PSI? It is a purely auto-moto-bicycle unit of pressure measurement that has survived since the mass production of pneumatic tires by the British company Dunlop Tires in 1891. It stands for pound-force per square inch. In addition, pressure is measured in:

  • bars (BAR), which in technology equate to atmospheres
  • international units Pascals (Pa).

Knowledge of these subtleties is necessary due to the discrepancy between the PSI bicycle pressure designation, the calibration of the pressure gauge scales, which are equipped with some pumps (compressors) and which control the level of bicycle tire inflation through the tube nipple. Usually pressure gauges are calibrated either in atmospheres or in pascals. To convert units when carrying out technical measurements, the following ratio is usually used: 1 bar (atmosphere) is equal to 100,000 pascals or 0.1 megapascals, which corresponds to 14.5 PSI.

Wheel pressure depends on:

The pressure for which the tire is designed is indicated by the manufacturer directly on it.

Inscription in English Inflate to. literally translates as Inflate up. (Pump up to, Pressure from. To.).

For example, the figure indicates that the pressure should be from 36 to 60 PSI (from 250 to 420 kPa) or, respectively, from 2.5 atmospheres to 4.2 atmospheres.

What should be?

Pressure standards are different for each type of tire.


Every bike lover is obliged to monitor the condition of his two-wheeled horse. It is from this that its service life and ride comfort will envy. When you go on your next trip, do not forget to measure your tire pressure. This procedure is mandatory, because the comfort while driving directly depends on it.

Oddly enough, first of all, the quality of cycling, especially on asphalt, depends on the pressure in the wheels of the bike. Under-inflated wheels easily break through and dampen a large percentage of the cyclist’s efforts, while over-inflated wheels can damage the camera and lead to its rapid wear. Accurate knowledge and experience of riding will help you find the middle ground.

Many are accustomed to checking tire pressure using the old-fashioned method with their fingers. However, this method is very imprecise, and the concept of a well-inflated wheel can be very different for every cyclist. That is why it is better to always have a pressure gauge on hand to accurately determine the tire pressure.

What is written on the tires

The secret to making the right choice is very simple: just look at the inflated wheel. Next to the information about the size of the tire, there will also be information about the permissible pressure range in the chamber.

Why is this information not shown on the camera itself? Because in it the only point subject to real stress is the nipple, and its mechanism is very reliable. Otherwise, the normal pressure, which increases by an order of magnitude during fast skiing, is taken by the tire, and how much it will be compressed is the main limitation.

So, if the pressure is too low, the tire will break closer to the rim, bite the chamber, leading to a breakdown, and if it is too low, it may just burst on one of the bumps or when driving on hot asphalt.

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Bicycle tire pressure: what should be and how to swing?

Cycling performance depends on the inflation pressure of the tire. Insufficient compressed air pressure in the wheels leads to more frequent punctures and breakdowns in the tube and tire. Excessive. to rubber abrasion. The optimal tire pressure can be determined based on your experience with proper cycling and manufacturer recommendations.

Bicycle tire pressure in extreme summer heat

If the temperature is high outside, it is better to reduce the pressure a little. Remember that the wheel can overheat. The hot asphalt itself and the friction of the tires on it heat the chamber and the air inside it, which accordingly increases the pressure. So, a tire inflated to its maximum value in hot summer can suddenly explode.

26″ To 700c Wheel Conversion On Mountain Bike

In more detail, the question of the effect of air temperature on tire pressure is described in a separate article The dependence of tire pressure on temperature. Calculation formulas are also given there.

Here, for example, we give a table for determining the pressure in a bicycle wheel from the air temperature, if it is inflated at a temperature of 20 ° C.

High lug tires

All toothed tires designed for travel on soft ground, sand, snow are best used with high pressure. In this case, the adhesion will be maximum.

For fatbikes

Fatbikes are best for riding on sand, snow and rocky roads. An example is winter movement on a road that is close to a railway embankment and is covered with a 10 cm layer of snow. The running zone of a fat bike tire is 2-3 times wider than that of rubber for a mountain bike or city bike. The large contact area of ​​the tire with the road brings the fat bike closer to the wheels of the motorcycle. On a fat bike, you can freely ride off-road forests and fields. The PSI chart is based on a rider with an average weight of 80 kg.

Here it is necessary to clarify a little what BAR, PSI and kPa are.

  • BAR is the pressure in bars or atmospheres. For our people, the most understandable designation. It is used in many countries, including the post-Soviet space. 1 BAR = 1 atmosphere
  • When the pressure in BAR is multiplied by 100, the result is kilopascals. In this case, it will be 250 and 420 kilopascals. Pascals are denoted by English letters “Pa” or if in kilo. then kPa. They sometimes do the same, indicate the minimum and maximum pressure for which the tire is designed.
  • PSI (pound-force per square inch). pressure in pounds per square inch. Used in Europe and some American states. It is designated as PSI or LBS / IN 2. For the given example, these are 36 and 60, respectively.

The relationship between BAR, PSI and Pa is as follows:

1 Bar = 1 atmosphere = 100,000 Pa (100 kPa) = 14.504 Psi,

With Bar and Pascals everything is simple, but with the translation of Bar to PSI everything is a little more complicated, so here is a table for quickly converting pressure in bicycle tires from Bar to PSI and vice versa:

We will mention another designation for pressure, which is called a kilogram of force per square centimeter or technical atmosphere and is denoted as kgf / cm² or kgf / cm². It is quite rare, but it happens. We will dwell on the technical nuances, there are a lot of articles on this topic on the Internet, let’s just say that for a bicycle pressure it can be considered equal to 1 Bar or one atmosphere.

And for lovers of exact mathematics, here are the conversion factors:

1 kgf / cm² = 1 atmosphere = 0.98 Bar = 98.07 kPa = 14.22 PSI

When pumping up a tire, you need to clearly understand that the pressure in it should not be lower than the minimum specified and higher than the maximum. It is worth noting here that it is better to leave a small margin of 0.2-0.5 atmospheres, without pumping the tire to the maximum value so that it does not burst, especially in hot weather.

About what else the manufacturer writes on bicycle tires, as well as what other numbers mean, there is a separate article on it on our website, which is called What do the numbers on bicycle tires mean?

Influence of pressure on ride quality

The correct tire pressure is a specific parameter for each bicycle and for its rubber. The bike owner creates a certain amount of pressure based on the quality of the roads where he rides, or none at all. Riding preferences and physical fitness play an important role. The minimum and maximum pressure is determined by the supplier of the specific rubber.

The increased pressure in the wheels allows the cyclist to save energy. By improving the movement of the wheels, a person can lengthen or complicate his route.

The pressure exceeding the limit set by the manufacturer is the reason for the puncture of the chamber from the inside of the rim. The side of the rim where the spokes go and where the protective rubber band runs will eventually break through the chamber with one of its side edges.

Below a lower pressure limit, the pressure will lead to a breakdown of the chamber, or a snakebite. It looks like two adjacent holes. The rim breaks through the camera in two places at once when the wheel hits an obstacle.

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The wheels must be inflated within the pressure specified by the manufacturer. In this case, the tire adheres perfectly to the road surface or to the road without any surface. The camera remains unharmed for many hundreds of kilometers.

The chamber pressure range is indicated on the sidewall of the tire. For example, a mountain bike tire says 1.95 inches wide. Inflate the wheel and measure the width of the tire using a ruler and two squares or a caliper. If the width matches the specified value, and the wheel feels elastic and hard, then you can ride. The width of the inflated wheel is not indicated on the camera. in this example, without a tire, it can inflate not to 1.95, but, say, to 2.1. When the camera is already sitting under the tire, the nipple itself takes on the load from the air expanding it from the inside.

The valve of the nipple. the spool. is reliable enough not to bleed air when the wheel of a stationary bicycle is inflated or when it is under working load during the ride. The pressure rating while driving is already taken over by the tire, and not by the chamber. The tire prevents the tube from swelling even further. The tube is securely held by the tire due to the shape given to all rubber by the cord and bead cable.

If the pressure is too low, the bicycle tire will sink under the weight of the cyclist. It blocks the camera, causing it to abrade, making it more penetrable. Excessive pressure at high speed will rupture rubber when hitting a bump, stone, rails or crack across the road, when driving on overheated asphalt.

Half slick

For semi-slickers, it is important to choose the right pressure for the very surface on which the bike rides.

Riding on a hard surface. asphalt and rolled primer. At low pressures, all the benefits of these tires are lost. A properly inflated semi-slick should roll on a hard surface with the smooth part of the tread. And on soft ground, side lugs are included in the work. At low pressure, the tire will flatten and grip the hard surface with the side lugs, creating additional resistance and wearing out faster.

When driving on soft ground, it is better to reduce the pressure. The low pressure cushions bumps in the road and makes off-road driving more comfortable. In this case, the contact area of ​​the wheel with the road increases, which, accordingly, leads to an improvement in grip. This is especially felt on descents and sharp turns.

When riding on sand or snow, it is better to increase the pressure. it will improve grip and control of the bike.

For city bikes and mountain bikes

For a teenage or adult road (or mountain) bike with a wheel diameter of 24, 26, 27 and 27.5 inches, a pressure of 2.2-4 bar is considered optimal. But a road bike can withstand tire pressure up to 5 atmospheres. Exceeding this value will damage the rim on the first bump or explode the camera after acceleration over 30 km / h, sharp braking. A wider rim holds the tube better than a narrower rim. The more elastic the tire is, the more pressure it may need. And this does not mean that it will break with the maximum value.

Maintain a fine line between traction and rolling. Inflated to maximum pressure, the tire will roll very well. And yet the grip will deteriorate sharply, since we are talking about a much lower speed. 5-30 km / h, and not 30-50. With a pressure below 2.2 atmospheres, the tire will noticeably wash out. Crossing and cornering balance will also suffer. The very first bump traversed at high speed (from 25 km / h) will lead to a snake breakdown.

The narrower the tire, the more pressure it will need. The above values ​​for mountain and road tires are suitable for a cyclist weight of 80-85 kg. The heavier the rider, the more wear-resistant rubber he needs, since the extra weight of a person requires more pressure. For dirt roads, off-road and asphalt, adjustments are also made.

Bicycle tire pressure versus cyclist weight

This should be immediately clarified. The pressure in the tires of a road bike always varies between 6.5-9 BAR (up to 130 PSI) and does not depend very much on the weight of the cyclist.

The pressure in mountain bikes is always lower.

Here is a table showing the dependence of the pressure in the wheels of a mountain and city bike on the weight of the biker:

You can focus on the following. for each additional kilogram of weight, the pressure should be increased by 1%.

The pressure in the tire directly affects its durability. Riding on badly inflated tires wears them out quickly.

How much pressure should be in bicycle tires

It would seem that it could be simpler. pumped up, crumpled with fingers, drove off. But no, there are some subtleties here. Tire pressure is the most important factor in rolling, floatation and bike handling.

I am not deliberately touching tubeless tires yet, because they are installed on more expensive bikes, and this is a topic for a separate article.

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