How many atmospheres is needed to pump a bicycle wheel

Mountain bike and road bike tire pressures

The limit of permissible tire atmospheres depends on the weight category of the cyclist; wheel width; tread pattern and road features.

Based on these parameters, the optimal pumping value is determined:

  • The pressure in 26-inch diameter bicycle tires indicates the pumping range from 2.6 to 4.7 atmospheric values, so when inflating, you must adhere to three to four atmospheres.
  • Wheel diameters from 28 inches require more atmospheric pressure for reels.
  • When riding on snowy plains, a small range of tire pressure is optimal, the more the wheel surface is in contact with the road, the higher the level of grip.
  • On a road bike, you can safely pump the camera up to the manufacturer’s maximum allowable limit, in which case you get the most optimal reel.

Tire type

Slick tires with a smooth semicircular tread surface are designed for driving on dry asphalt, give good roll, speed and require pressure close to the upper permissible limit.

Semi-slick. with a smooth center section and small spikes on the edges of the tread. a versatile rubber for most situations. Good roll-off and speed are maintained, the ability to drive on wet road surfaces and dirt roads of varying degrees of difficulty is added. The pressure close to the maximum must be adjusted depending on the hardness of the road surface, ambient temperature, human weight.

XC tires are good for riding through forests and rough terrain. They pump up to an average 3-4 atmospheres.

Cycle tires with grousers need to spend more time in order to experimentally select personal pressure parameters. You need to focus on values ​​that are high enough to provide the best grip on loose soils.

To find the optimal tire pressure for your bike, you can consult our tables.

Tire types and road features

Bicycle tires with smooth treads are used exclusively for riding on asphalt tracks.

The atmospheric indicator in bicycle tires should be at the maximum limit: the more atmospheres, the higher the roll.

Multifunctional semi-slick models are suitable for riding on asphalt and soil. Bicycle tires also require good inflation for optimal roll on asphalt and traction on unpaved tracks.

Cross-country wheels with teeth are intended for riding on soil coverings. The higher the tire pressure, the more traction.

Read a separate article about the types and choice of tires.

The ratio of the weight category and the pressure inside the chamber should be calculated independently by the method of checks, but there is a standard table that determines the optimal value:

Bike type

The wheels of a road bike are inflated almost to the upper limit specified by the tire manufacturer, before reaching 0.2-0.4 atm. This difference guarantees the safety of the tire from bursting when the temperature and pressure rise.

A mountain bike requires an individual selection of the parameters of the normal air pressure in the wheels, depending on the weight of the rider and the terrain of movement. Experimentally, taking a pump with a pressure gauge with you on a trip, you need to find the pressure at which the balance between coasting and grip will be the best.

Main characteristics

The optimal level of atmosphere in bicycle tires is determined independently and depends on the riding style, characteristics of the road and professional training.

    High tire pressure increases roll, speed and saves the rider’s energy.

Pressure exceeding the recommended standards is fraught with a puncture of the bicycle tube on the inner surface of the rim ring.

  • Below recommended pressure can also damage the rubber on the rim surface.
  • Medium non-degrading atmospheric values ​​prevent tire puncture on uneven surfaces and increase traction, making it easier to ride on rough terrain.
  • As a result, the chambers are filled with enough air to ensure traction, but do not damage the bike. There are standard parameters for defining acceptable boundaries for all types of cameras.

    Weather

    The temperature difference between the ambient air and the road surface in winter and summer seriously affects the readings of the pressure gauge. In the heat, the pressure inside the bicycle rubber increases, in the cold it drops. This should be taken into account when inflating the wheels.

    Summer pressure parameters must be reduced, avoiding approaching the maximum values, in order to prevent the tire from bursting. In winter, sometimes it is even possible to exceed them, this will only improve the comfort and safety of traffic. Especially inflating tires to the upper limits is shown when driving in snow.

    How is blood pressure measured?

    It is customary to designate pressure in three units of measurement:

    • Psi. pound-force per square inch. pound-force per square inch;
    • BAR. bars, usually equated to measurement in atmospheres;
    • Pa. pascal.

    Since many tire manufacturers focus on the American market, the Psi designation is most often found. In English-speaking sources, it is usually simplified to pound, or pound, i.e., when they say that a pressure of 2 pounds, they mean Psi. This unit of measurement is outdated, used only in the USA, but, as they say, it is more alive than all living things.

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    Bars are also obsolete units of measurement, but are actively supported in Russia and many other countries, incl. European. This unit of measurement is actively used, as it has something in common with the atmosphere, which is quite convenient for measurements.

    Pascal is the only metrically correct unit on the list, but rarely used in bicycle designations.

    The ratio between all units is as follows: 1 Bar = 100,000 Pa = 14.504 Psi.

    Pressure effect

    In fact, the optimal pressure in the tires of a bicycle is a purely individual parameter that each biker varies within certain limits for himself: for his riding style, for the planned route and the current level of training. The limits are set by technological constraints, which we will consider further.

    many, atmospheres, needed, pump, bicycle

    Here are the main factors to consider when choosing an inflation level:

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    • high pressure gives rise to rolling speed, saving the strength of the cyclist;
    • excessively high, in turn, can provoke a breakdown of the chamber against the rim from the inside;
    • similarly, low pressure leads to snake bites, when a rim on an obstacle or bump pierces the chamber at two points at once and reaches the tire;
    • low pressure prevents damage to mechanisms on numerous bumps;
    • at low pressure better grip and easier to move over rough terrain.

    Taking into account all the pros and cons, a single recommendation can be made: the wheels should be inflated enough to provide good traction and not damage the camera. For this, there are standards for what pressure is considered acceptable. We will consider them further.

    How is blood pressure measured?

    It is customary to designate pressure in three units of measurement:

    • Psi. pound-force per square inch. pound-force per square inch;
    • BAR. bars, usually equated to measurement in atmospheres;
    • Pa. pascal.
    many, atmospheres, needed, pump, bicycle

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    Since many tire manufacturers focus on the American market, the Psi designation is most often found. In English-speaking sources, it is usually simplified to pound, or pound, i.e., when they say that a pressure of 2 pounds, they mean Psi. This unit of measurement is outdated, used only in the USA, but, as they say, it is more alive than all living things.

    Bars are also obsolete units of measurement, but are actively supported in Russia and many other countries, incl. European. This unit of measurement is actively used, as it has something in common with the atmosphere, which is quite convenient for measurements.

    Pascal is the only metrically correct unit on the list, but rarely used in bicycle designations.

    The ratio between all units is as follows: 1 Bar = 100,000 Pa = 14.504 Psi.

    What to pump up

    Bicycle luggage requires maintenance and pumping very often. Even on the most enduring city and mountain bikes, it is required to check and pump up the camera every 2-3 weeks, since the air leaks not only through the nipple, but also simply through the rubber. High pressure helps air molecules find their way through an insufficiently dense chamber.

    City, or, simply, budget bicycles, it is enough to pump up once every 2-4 weeks, mountain bikes. at least once every two weeks, road bikes. once a week, and road and sports bikes. before each trip.

    Therefore, the pump is not only an emergency accessory that is used only when a punctured wheel is changed, but also a necessary part of the preparation for departure. Active cyclists should consider purchasing two pumps:

    • portable. as part of an emergency kit or on long trips;
    • stationary with a stop and a pressure gauge. for periodic maintenance of your tires.

    By the way, an ordinary car pump perfectly takes the place of a stationary pump. It is also suitable for bicycles, shows, shows exactly how many atmospheres are pumped up, and does not take up additional space. Some people prefer to pump up on professional pumps at gas stations, but the absence of their own professional tool can play a bad joke in the event of an unexpected situation or when you deviate from the standard route.

    Bicycle tire pressure

    How much inflate the wheels? Many cyclists ask this question quite often. All well-known tire manufacturers indicate the size of the recommended pressure on the side of the tire. Most often this figure is in the range from 35 to 60 psi (from 2.38 to 4.08 atmospheres).

    A common mistake many novice cyclists make is overpressure in mountain tires or insufficient pressure in the wheels of a road bike.

    There are factors to look out for when looking for the ideal tire pressure:

    Cyclist’s weight. The performance of a tire at a given pressure depends on the weight of the rider. For example, a 66kg rider may find that 2.38 psi for a 26×2.25 tire is too high and grip is not good enough. Conversely, a 113kg rider may find that their tires are under-inflated and therefore bend and deflate.

    The table shows tire inflation data for a mountain bike with a tire width of approximately 2 inches.

    Tire volume and pressure are two inextricably linked indicators. The volume of the tires determines how a certain pressure will appear to you. For example, a 700 x 25 mm tire inflated to 2.38 psi will be practically flat, while a 26 x 3.8 inch tire inflated to the same 2.38 psi will feel firm to the touch. the wheel will bounce. on uneven surfaces, rather than absorb them.

    Much depends on the area. If you ride mostly on rocky tracks, it is better to inflate the tires a little more in order to avoid tire deflection and damage to the side section.

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    1.) Primer, potholes. inflate to an average value (guided by the readings on the tire) or slightly less.

    2.) Asphalt, rolled paths. pump almost to maximum.

    Your riding style is just as important as the terrain you are driving. The more aggressive the riding style, the more the wheels need to be inflated. Are you trying to choose the flattest sections of the track, bypassing the hills, or do you like to drive forward with indomitable energy? Do you like to keep the wheels on the surface or do you like to bounce on the bike, overcoming obstacles??

    Rim width plays an important role in determining the lowest possible pressure without sacrificing efficiency. A wide rim holds the tire better than a narrow one. It allows you to use lower tire pressure without sagging.

    The design of a tire affects how it behaves at a given pressure in about the same way as the weight of a cyclist. High TPI tires are more flexible. TPI is the amount of nylon fibers per square inch of tire base. Low TPI tires have better puncture and tear resistance but are heavier. Higher TPI provides better traction, offering a smoother, softer ride and lighter construction. Typically, TPI values ​​range from 24 to 130.

    Typically, tire pressures range from 35 to 48 psi (2.38 to 3.26 atmospheres). This pressure provides control over the road and maximum grip of the tires with the surface. An over-inflated tire to 50. 60 psi (3.40. 4.08 atmospheres) reduces ride comfort because the tire has less contact with the road.

    many, atmospheres, needed, pump, bicycle

    When riding on asphalt, an inflated mountain bike tire wears out very quickly.

    An insufficiently inflated tire 28. 32 psi (1.9. 2.17 atmospheres) is also fraught with danger. Because of this, you can easily punch through the camera by hitting a stone or simply hitting an uneven track. Under this shock load, the chamber is pinched between the rim and an obstacle, which can cause a snakebite. It will be difficult to fix a puncture of this kind. There is also a high probability of damage to the rim itself, this can entail expensive repairs or even replacement with a new one. It should be borne in mind that a badly inflated tire on a steep bend can be ripped off, and this can cause a fall. Most often, a breakdown occurs on the front wheel and is accompanied by a loud bang of the camera, as it easily bursts, having lost the protection of the tire.

    Attention! Do not exceed the pressure indicated by the manufacturer on the tire sidewall!

    On surfaces like snow and sand, inflated wheels will respond better. In extreme heat, when driving at high speed, it is better not to inflate the tires to the maximum, as there may be overheating of the wheels. In winter, the wheels need to be inflated more, otherwise there may be damage to the tires and the tube from the cold.

    Road bike wheels should be inflated to 95-135 psi (6.46. 9.18 atmospheres), as the air volume in them is less than in mountain bikes.

    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.

    Markings

    What do they write on the tires? For example, (2.38-4.0) is clearly atmospheres, or BAR, and (95-135) is Psi. If the figure has more than 3 digits or the prefix k (kilo), we are talking about metric Pascal. Most often, the desired value is located under the size designation and is duplicated in BAR and Psi in the form of a range, clearly indicating to what pressure you can pump.

    Actually, the manufacturer specifies the range within which the tire can function, then. the freedom of the cyclist.

    What is written in the table

    After you open the hatch of the car’s gas tank or the driver’s side door and find the table, you need to understand what it says. In the cheat sheet for the car owner, the correct value of the pressure in the car tire of the rear and front wheels should be indicated, tied to the following parameters:

    • profile width in millimeters (175/70 R13 82 T);
    • the percentage of the profile height to its width (175/70 R13 82 T);
    • the diameter of the wheel disk of the car in centimeters (175/70 R13 82 T);
    • index of permissible tire load in kilograms (175/70 R13 82 T).

    Find your tire in this list and follow the line, moving from left to right, to a group of numbers that should display the correct pressure in three units of measurement. bar / kPs / psi (240 / 2.4 / 35). over, the first group of numbers should indicate the desired characteristic of the front tires, and the second. the indicator to which the rear wheels of the car are pumped. In most cases, both indicators are the same, but some machines may have different correct values.

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    Is nitrogen injection needed?

    Some time ago, tire specialists assured that in the case of pumping nitrogen into the tires of a car, changes in the pressure density during temperature changes or heating of the wheels practically did not occur. The procedure for pumping nitrogen into the wheels, in contrast to the usual air, is more expensive. But recently it has been proven that this does not lead to changes and this is an extra waste of money, therefore, we will not talk about this.

    Markings

    What do they write on the tires? For example, (2.38-4.0) is clearly atmospheres, or BAR, and (95-135) is Psi. If the figure has more than 3 digits or the prefix k (kilo), we are talking about metric Pascal. Most often, the desired value is located under the size designation and is duplicated in BAR and Psi in the form of a range, clearly indicating to what pressure you can pump.

    Actually, the manufacturer specifies the range within which the tire can function, then. the freedom of the cyclist.

    Weight changes

    For heavy riders or heavily loaded bikes, it is very important to add pressure, as a lot of mass will squeeze the wheel of the bike and problems with insufficiently inflated cameras can come out much earlier.

    Recommended pressure for weight addition is 1% for every kilogram of rider weight over 50.

    What will happen to the car if you neglect the recommended pressure

    Do not under any circumstances inflate the wheels of the car to the level indicated on the tire beads. This parameter refers to limit values. The decision to pump the tire to the limit can cost you your life and health. with this pressure, the tire should burst, unable to withstand the load. Therefore, it is not recommended to pump tires up to 50 psi. Try not to swing the wheel above the normal level mentioned in the table. you will change the dynamics of the car and lose control. Excessively tight tires lose traction, which leads to an increase in braking distances. In addition, in this case, the load on the car will increase. the suspension will receive more shocks from the pits, and hitting a speed bump will end up with serious repairs.

    Give up the idea of ​​reducing the required pressure value for the sake of increased cross-country ability of the vehicle. Yes, this scheme works as it should and is recommended in total off-road conditions, however, a car with half-flat tires (relative to the normal indicators recorded in the table) over-consumes 0.5-1.5 liters of fuel for every 100 kilometers.

    Not every driver pays attention to the tire pressure of their car. But the safety on the road, handling and maneuvering of the car sometimes depends on the pressure in the tires. In addition, the tire pressure level affects:

    • for fuel consumption,
    • uniform wear of the wheel itself,
    • can cause hernias on the wheel court.

    If the pressure in tires r13 and r14 is increased, then, for example, when hitting an obstacle, the tire may even explode. Incorrect tire pressure r15 will also affect maneuverability when cornering, turning, etc. Best of all, at different levels of inflation of car wheels, the following figure will show.

    As you can see, already by the wear of the tread it is possible to determine what the problem of pumping the rim is, but it is better not to bring this up to this, but to maintain a certain atmosphere at the required values.

    The tire pressure must be checked at least once a month. Professional drivers check every 2 weeks and before every long journey. And an external inspection of the wheels should be daily before starting the car engine. Although if you are a happy owner of low-profile tires, then it is impossible to determine what pressure should be in tires by eye.

    Summer and winter pressure. is there a difference

    How much to pump the tires is not only up to the automaker, but also nature itself. After all, the norm in bars or kilopascals must correspond to the parameters of vehicle operation (average speed, number of passengers, weight of luggage) and weather conditions. The manufacturer does not recommend exceeding the rate indicated in the table, neither in winter nor in summer. However, this happens without the participation of the driver. After all, the pressure in a system with a stable volume depends on the air temperature inside the tire.

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    Pumping car tires to normal in a cold garage, you get a completely abnormal value when driving on asphalt warmed up to 40-50 ° C. The opposite effect is also possible, when the wheel is pumped in a heated garage or box of a car workshop, and then the rate set on the pressure gauge turns into a record low on any icy road. Therefore, in case of temperature jumps of 10 ° C, it is recommended to correct the pressure by 0.1 bar, lowering or pumping up the tire.

    As a result, even with normal pumping of the car wheels, you should monitor the level at weekly intervals. And in the off-season, the pressure in car tires should be checked at least every other day.