HIGH OR LOW PRESSURE?
Every bicycle tire has a minimum and maximum pumpability written on the side of the tire. Among advanced MTB, cyclocross and gravel bike users, there is also a tendency to use values that are even lower than the recommended ones. Since there can be up to 2 bar in a tire compartment (eg 2 to 4 bar), it should be borne in mind that when using extreme pressures from such a compartment, our motorcycle will behave completely differently. Before we move on to the answer to the question “how much to pump?” so we want to indicate what we gain and what we lose by using a higher or lower pressure.
On the other hand, we have a low pressure due to which the tire starts to work. Lies on the ground, works gently in turn. It offers significant shock absorption and better traction. Does it have any disadvantages? Unless we go too low, no (in terms of driving performance, of course). The facts, however, are that there is a fine line between a perfectly shock-absorbing and grippy tire and an under-inflated tire. To achieve the above, we want to pump as little as possible. This, in turn, can lead to too much flattening of the tire during travel and slight wiggle when pedaling. In this case, the rolling resistance increases significantly. In addition, too little air can easily damage the compression. This is why it is worth applying as little pressure as possible, but not sinking so low that we feel that our back is clearly swinging. It is designed to wrap around terrain and does not create excessive elasticity in the tire.
However, while driving many tires, we have noticed that the minimum pressure recommended by manufacturers is usually so high that it is difficult to talk about any flattening or a clear increase in the risk of a defect. For example, for a 29 “x 2.2” MTB tire, the minimum recommended pressure is usually 2.1-2.2 bar. This is a lot, because, for example, most players use values of 1.4-1.7 bar with a weight of about 55-70 kg, 1.6-1.9 with a weight of about 70-85 kg, or 1.8-2.1 with a weight in the range of 80-100 kg. They do this because the gains from low pressure are enormous, and it is still so much that there can be no question of a dramatic increase in rolling resistance or a clear risk of impact.
WHAT PRESSURE TO CHOOSE?
When it comes to bicycles that run on prepared roads, that is, two-wheeled: city, trekking, cross country, road, etc. it is worth trying to get closer to the minimum recommended by the manufacturer. This value will not slow down the tires significantly, but will significantly increase comfort and traction. If you are clearly heavier than around 90-100 kg, you can try to get closer to the upper limit, but don’t overdo it. The tire must always run smoothly and not be as hard as stone. You can even ask the person riding with us to see if our tires flex when hitting bumps or obstacles. This should work a little. On road bicycles, users often use maximum allowable values - but this only makes sense when the road surface is perfect and the weather is good. Only then will the benefits of lower resistances outweigh any other losses.
If, on the other hand, we are talking about bicycles that ride on difficult terrain, with very limited grip. that is, mountain, cross-country and gravel bikes, it is worth going even below the minimum pressure recommended by the manufacturer. Of course, in the case of narrow tires (gravel and CX), this will be at the expense of a significant increase in the risk of catching sneakers, but remember that these are absolutely rigid bikes and the tires are almost the only source of grip and comfort. When it comes to MTB. as we wrote above. values well below 2 atmospheres are the norm for bikes with 29-inch wheels and wide all-terrain tires.
Thus. For recreational and service bikes and road bikes, we recommend looking for the ideal pressure in the range described on the tire, with an emphasis on experimenting with the lowest possible value. On the other hand, in the case of cycling on rough terrain, mainly MTB, it is worth going below the recommended minimum. As low as possible, but enough so that the tire doesn’t flatten too much and slows us down in the easy stages. By the way, it did not become susceptible to compression and did not work too hard in corners (the problem of tires with soft, thin sidewalls).
The advantages of using high pressure include lower rolling resistance, that is, faster driving and less risk of damage to the tire or inner tube when compressed. However, driving on very hard tires has many more disadvantages than advantages. First of all, the tire is not very susceptible to deformation, which means that it absorbs bumps unevenly, and what is worse (you can overcome discomfort), it holds the surface much worse.
It doesn’t work when cornering, it doesn’t fit into the terrain, and wherever there are irregularities, it jumps like ping-pong. As a result, it provides much poorer grip, which means we have less cornering safety, more braking distance, and less smooth ride. Not only that, scientific studies show that such a tire constantly creates micro-shocks when it rolls on a less smooth surface, which wastes our strength.
So the facts are that pumping up to the manufacturer’s recommended pressure range only makes sense if: the surface is perfectly smooth, the rider weighs over 100 kg, or has a unique tendency to catch rubber when tapped. Otherwise, a tire that is too stiff will have little grip and be uncomfortable.
Bicycle tire pressure. what should be?
Inflation of tires is one of the basic services performed by every cyclist. First of all, it should be said that the correct pressure is selected individually for each bike user, taking into account his weight, bike type, wheel size, tire width, riding style and personal preference. Sounds complicated? Perhaps, but in practice it is enough to follow a few tips and then through trial and error you can get a feel for which setting is best for you. It’s worth your time for the whole process, because given how much pressure is actually changing, the game is just worth the candle.
While riders and advanced riders who treat cycling as a passion usually know how to set the right pressure, among beginners or cyclists, one of two absolutely extreme practices can be seen. A large group of cyclists use tires with too low pressure. Probably because there is no permanent access to the pump. The second group, on the other hand, are people who inflate tires “on stone”. Perhaps the increase in pressure “in reserve” is also a mistake. The fact is that neither too high nor too low a pressure will do.This should be appropriate, that is, within the range suggested by the manufacturer (although even lower in some cases).
HOW OFTEN DOWNLOAD?
Of course, as often as necessary, i.e. with a loss of air. Remember that thin tires with high pressure (e.g. 7 bar) will lose air faster than MTB tires inflated to 2 ATM. Therefore, it is possible to establish certain (very general) patterns, which in tires up to 32-33 mm we check and, possibly, supplement them every week, and in wider tires every 2 weeks. These are, of course, only estimates and averaging. Air loss is affected by the thickness of the inner tube or the presence of tubeless tires. For example. in thin latex tubes you need to pump every ride. That is why it is worth checking and, if necessary, adjusting the pressure before every ride in which we care about the “quality” of our tires (ambient temperature also affects them). Apart from these cases, such as on a city bike or other recreational and service bike, it is worth checking them every two weeks for peace of mind.
Take the survey
- High pressure. provides excellent roll and at the same time saves the cyclist’s energy.
- Very high pressure. provokes tire breakdown due to friction against the rim from the inside.
- Small indicators. cause double punching of the tire when overcoming bumps, irregularities in the road.
- Low pressure. optimal for mountain bikes, riding on rough terrain.
Taking into account the peculiarities of different pressure indicators, we can conclude: the chambers should be inflated so that they provide full grip on the road surface, do not provoke wheel damage. The minimum and maximum allowable values are usually indicated on the side of the tires.
Too low pressure in the wheels of the bicycle leads to breaking tires, biting the tube, which increases the risk of punctures and punctures. High performance accelerates rubber wear. The optimal parameters are calculated based on the manufacturer’s recommendations and experience, the skill level of the cyclist.
The tubes should be inflated so that they provide full traction and do not cause damage to the wheels.
So let’s summarize
When riding a mountain bike in the city and a rolled primer, this is 3-3.5 atmospheres. For movement on the ground. 2.5-3 atmospheres
At the same time, if your weight is more than 80-100 kg, feel free to add another 0.5 atmosphere to the wheels (watch out so as not to go beyond the maximum pressure).
If you have a road bike. feel free to pump up 3.5-4 atmospheres, looking at the limit values indicated on the tire.
The general principle is that the narrower the tire width, the higher the pressure in the wheel.
Another point from the experience of cyclists. If you are using anti-puncture tape to protect the tube from punctures, try to maintain a slightly higher pressure in the wheel. Everything is simple here: the higher the pressure, the tighter the tape lies between the camera and the tire, does not “fidget” and does not move during sudden braking and cornering, and better performs its function.
Remember, you can find the optimal pressure for yourself only after cycling for a while. Each cyclist has a different weight and riding style. In this case, the same pressure for one will be optimal, and for someone too low or high.
In fact, the optimal pressure in the tires of a bicycle is a purely individual parameter, which 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.
Here are the main factors to consider when choosing an inflation level:
- high pressure gives “roll-over”. 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 on 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.
Mountain bike tire pressure
Off-road bikes are a little more complicated. The point is, here you need to strike a balance between grip and coast. The more inflated the tire, the better it rolls (on a flat and hard surface), but due to the rigidity it cannot “lick” the surface. the grip deteriorates.
High pressure maintains the semi-circular profile of the tire, while maximum grip is possible when the full contact patch is involved. In other words, the more the tire “flattens”, the better for cross-country ability and control. On the other hand, if you pump too weakly, the roll will suffer and the same “snake bite” is possible.
Since basically all chamber mtb rubber has an allowable pressure range of about 2-4 atm, then I would say that the working pressure is between 2.2 and 3 atmospheres for an adult man weighing from 75 to 90 kg. It is impossible to say more precisely. there are a lot of factors, you need to experiment with a specific tire and a specific trail where you ride.
Different tires behave differently at the same pressure, and the behavior also depends on the width of the tire, it is believed that less pressure can be pumped into a wider one. The weight of the cyclist is very important, for obvious reasons.
Take a pump with a pressure gauge with you and try to find the lower pressure limit at which the tire still does not break. Then try how the bike rolls at that pressure. Add air if needed. You need to find a middle ground for both soil and asphalt.
What should be the pressure in the tires of the bicycle?
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.
Now about the effect of ambient temperature on pressure.
The permissible pressure range for a bicycle tire is usually within a couple of atmospheres. This margin allows you to vary the pressure, depending on the surface you plan to ride on and your weight.
When driving on smooth, decent asphalt or other hard surfaces, keep the pressure close to the upper permissible limit. If, while riding a bike, you pay attention to the rear wheel, you will notice that the tire is squashed under your weight, due to which the contact surface with the asphalt increases, friction increases, and significantly more effort will have to be applied to create driving force.
However, the worse the surface, the less comfortable it will be to ride on poor surfaces. The density of the wheels will not allow you to absorb bumps, so each bump will give off at the fifth point, and overload all bicycle systems. For this reason, when driving on unpaved surfaces, or bad asphalt, it is better to lower the pressure and maintain it in the area of the lower permissible boundaries. This pressure will also allow for better traction. On poor surfaces, although this will create additional friction, requiring a lot of effort from the cyclist, however, it will allow you to maintain the bike’s controllability in case of extreme situations.
For a beginner who does not know the peculiarities of local reliefs, all of the above can be taken into account and use the universal table. You need to pump up to the number of atmospheres corresponding to your weight, and you can already feel confident on the road.
What you need to know about bicycle wheels
In order to accurately measure whether the wheels are sufficiently inflated, you must have a pressure gauge with you, a special device for measuring the number of atmospheres in the tires. However, the optimum pressure may vary depending on the type of tire and its manufacturer.
A bicycle tire consists of a tube and a tire. The tire is responsible for the limiting pressure values. Regardless of the chamber, the optimal pressure to be maintained in the tires depends on the values indicated on the tire.
Regularly checking the tire pressure and keeping it within acceptable limits will have a positive effect on tire life, and will contribute to the most comfortable ride, while spending the least effort to maintain and develop speed.
Find your sport
Many cyclists do not often think about how to properly inflate the wheels and how much pressure should be maintained in the bicycle tires. Keeping track of the technical condition of a two-wheeled friend is quite a routine task, so checking the pressure in bicycle tires is often carried out visually, at best by touch.
How to find out the pressure in the wheels of a bicycle
The best way to find out how much pressure is in the wheels is to use a pressure gauge. In this case, it will be most convenient to acquire a pump with a built-in pressure gauge. With such a pump, the required pressure can be set the first time. Having such a pump with you, you can quickly change the pressure along the route, depending on the surface, which is most favorable for its passage.
What units of measurement apply to pressure?
Most often, tire pressure is measured in atmospheres (kg / cm2), or bar (1 BAR = 0.980655 kg / cm2). But sometimes other metrics are used as well. The imperial metric system, which is used in most countries of the former British Empire (UK, USA), uses PSI (pound per square inch). 1 PSI = 0.068 BAR. Pressure can also be measured in Kilopascals (kPa). 1 kPa = 6.8964 PSI. It is important to understand how these metrics relate, as different automakers may use different designations. For convenience, we present a table for converting tire pressure.
Conversion of pressure values in different calculation systems
What should be the tire pressure?
There are four main factors that affect optimal tire pressure: temperature, axle weight distribution, vehicle utilization, and rim diameter.
- Temperature has a direct effect on tire pressure. The higher it is, the higher the pressure. On average, we get /.0.1 BAR of pressure for every /.8 ° C from room temperature.
- The weight is distributed differently along the axles of the car, respectively, and the pressure in the front and rear wheels should be different. Consider this when inflating tires.
- The more passengers or cargo the car carries, the more it will “sink”. To compensate for this, increase the tire pressure.
- Wheel size also affects optimal pressure.
But don’t worry, you don’t have to sit with a calculator and calculate the correct pressure. The engineers have already done this for you. On the body of almost every car, you can find a reminder with the recommended tire pressure. Usually, it is located on the inside of the fuel filler flap or on the driver’s door pillar. There you will find the optimum values for different wheel sizes and machine weights. Tire manufacturers also give their recommendations.
What should be the pressure in tires on winter tires with spikes?
AutoReview specialists conducted testing to find out how much tire pressure should be in winter. To do this, they took a Lada Vesta (1.6 manual transmission, 106 hp) with Continental Ice Contact 2 studded tires and carried out three experimental measurements. With recommended (2.1 BAR), reduced (1 BAR) and increased (3 BAR) blood pressure. The speed of acceleration (from 5 to 28 km / h) and braking distance (from 28 to 5 km / h) on ice were assessed.
The flat tires behaved the worst. Acceleration is 10% slower than recommended pressure and braking distance is 2 meters longer. On the other hand, inflated wheels performed better, although not by such a noticeable difference compared to the control readings. The mechanics who conducted the experiment explain such a result by the fact that at increased pressure in the tires, although the contact patch decreased, but the spikes protruded more, and, accordingly, better adhered to the icy surface.
How to determine the correct tire pressure in winter?
Tire pressure seriously affects how a car behaves on the road. It is especially important to understand how to swing winter tires, because the weather conditions in the cold season in themselves create additional difficulties in driving. Depending on the degree of pumping, the properties of the wheel and the contact patch change. This affects maneuverability and braking distances, which can become decisive in difficult road situations. This is why it is so important to keep the tire pressure at the optimum level. We will find out everything you need to know about it about what should be the tire pressure in winter.
How to set the perfect tyre pressure
What does tire pressure affect??
As already mentioned, tire pressure directly affects the vehicle’s agility and braking distance. It’s all about how the tire contact patch is distorted. Under normal pressure, the wheel is in full contact with the road. Tire wear occurs evenly, and the tread performs its functions correctly. If the tire is deflated, then contact with the coating occurs only on the sides of the wheel, and if it is pumped over. in the center. This not only shortens the “life” of the rubber, but also poses a threat to traffic safety.
How a wheel makes contact with the road at different pressures
Consider what happens at different degrees of pumping of the wheel:
- Flat tire (35% of normal pressure). On such tires, the car is obviously “crouched”. You won’t be able to travel much. only a couple of kilometers. The disc will catch on the tire and damage it.
- Lowered wheel (40-75% of normal pressure). It is impossible to drive on an asphalt and other hard road for a long time. At a sharp turn or maneuver at speeds above 50 km / h, there is a risk that the tire will simply “jump out” of the disc. True, on flat tires it is better to overcome harsh off-road conditions on soft surfaces (viscous mud, wet snow). When a difficult section is passed, it is worth returning to normal pressure. It is better not to drive on asphalt and other hard surfaces, as well as at high speeds.
- Slightly lowered wheel (85-90% of normal pressure). With such an insignificant underproduction, you can drive for a long time without much discomfort and the danger of wheel damage. On the contrary, the car starts faster and runs smoother. But controllability suffers. This is beneficial when driving in a straight line and can be useful if you are a street racer. But it is unlikely to please in everyday driving. fuel consumption with such pressure in the wheels is higher, and tire wear is faster.
- Correctly inflated wheel (normal pressure). If the tire pressure is optimal and in accordance with the recommendations, the car will behave predictably. The contact patch is enlarged and the tread is in full contact with the road. Tire wear occurs evenly, which means you will have to spend less on buying new tires.
- Slightly inflated wheel (110-115% of normal pressure). The contact patch is distorted and the handling on the asphalt is slightly impaired. The ride gets stiff. However, for studded tires in winter, this pressure can be a plus. With this pumping, the spikes stick out a little and better contact with the icy surface.
IMPORTANT! If the pressure level in the wheel is incorrect, there is a danger of aquaplaning. Due to the fact that the contact patch is distorted, the tread pattern cannot fully fulfill the function of removing liquid: wet snow or water.
Mountain Bike Tyre Pressures – Everything You Need To Know
How temperature affects tire pressure?
We have already talked about the effect of temperature and the fact that it is important to take measurements on a “cold tire”. But when checking the pressure in the wheels in winter, it is important to consider one more point. If the car at this time is in a room where the temperature may differ by 20-30◦ from the street temperature, 0.2-0.4 BAR of pressure is immediately lost when entering the road. The ride will be softer, but the acceleration and deceleration will be longer. This nuance is important to keep in mind.
In summer, on the contrary, it is important not to pump tires. If in winter the tire pressure decreases following the air temperature, then in hot weather other factors also warm up the wheel. For example, driving fast increases friction, and hot asphalt is much warmer than the air. Thus, if you eat at a high speed on a hot summer day, the wheel temperature can easily reach 100 ° C and higher. The pressure becomes noticeably higher than normal and hitting a stone or bump can rupture the tire.
How tire pressure in winter depends on size?
There is a misconception that the optimal pressure level for tires depends on their size. On Internet forums you can find a lot of questions like “how does the pressure in winter tires r15 differ from r16″. To a certain extent, this factor, of course, influences, but is not decisive. Take, for example, wheels measuring 235/55 r17. If you put them on the Opel Astra, the recommended pressure is 2.1 BAR. But the same wheels are installed on the Volkswagen Multivan. On it, the tires will have to be inflated to at least 2.9 BAR. If the “aster” is tightly loaded, then, according to the manufacturer’s advice, the pressure on the rear axle will need to be given a pressure of 2.6 BAR.
Let’s consider how the recommended pressure depends on the wheel size using the example of several popular models.
Recommended pressure in winter tires Nissan Qashqai (Nissan QASHQAI), depending on the size of the wheels:
- R16. 2.3 BAR for the front wheels, 2.1 BAR for the rear wheels. Fully loaded. rear 2.6 BAR.
- R17. 2.3 BAR front and 2.1 BAR rear.
- R19. 2.3 BAR for the front axle, 2.6 BAR for the rear.
Recommended tire pressure in winter Ford Focus, depending on wheel size:
- R15. 2.1 BAR on both axles, at maximum load. 2.4 BAR.
- R16. 2.1 BAR for petrol versions, for diesel. 2.3 BAR.
- R17-R18. 2.3 BAR, or 2.5 BAR at maximum load.
Recommended tire pressure in winter Toyota Corolla (Toyota Corolla), depending on the size of the wheels:
- R15. 2.2 BAR on both axles, 2.5 BAR. when loaded at maximum.
- R16. 2.2 BAR on both axles, 2.5 BAR. when fully loaded.
As you can see, there is some connection between the size of the wheel and the pressure in it, but it is clearly not worth putting this factor at the forefront. Better pay attention to the workload of the machine and the operating conditions.
What should be the pressure in the tires of your bike?
Oddly enough, the comfort and convenience of cycling depends very much on the pressure in the tires. If a wheel is poorly inflated, it impairs handling, slows down the ride speed, requires more effort from the cyclist and is easy to puncture. Over-pumping the wheel will reduce comfort (in the case of rough terrain) and also increase tube wear. You can find a middle ground if you have certain knowledge and experience in cycling.
The optimal tire pressure is an individual parameter and may be different for each person. It depends on the riding style, on the surface that the route will pass through (rough terrain or flat road) and also on the skills of the cyclist himself. But there are still pressure limits that are worth considering and which we will consider further.
When inflating the wheels, keep in mind:
the more pressure, the better the roll. and, as a result, the economy of the cyclist’s energy;
very high pressure can lead to breakdown of the chamber against the inner wall of the rim;
excessively low pressure can also lead to breakdown;
low pressure reduces the load on the mechanisms (and, accordingly, reduces the risk of damage) when driving on various irregularities;
low pressure improves grip and makes it easier to ride on rough terrain.
Taking into account the above, we can conclude that the wheels should be inflated so that they provide good grip on the road surface and at the same time do not lead to a breakdown of the chamber. For this, standards for permissible pressure are provided.
Information on the tire
In order not to be mistaken when choosing the optimal pressure, just look at the tire. Next to the tire size information, the range of permissible chamber pressure will also be indicated. Some may wonder why this information is not indicated on the camera itself. The fact is that the main load when inflating the wheels, and indeed when driving, is taken up by the tire, therefore the maximum and minimum pressure in the wheel depends only on its capabilities. In the chamber, the nipple is the main vulnerability, but it is usually well sealed and protected.
Now let’s look at the units of measure for pressure:
Psi. pound-force per square inch;
Bar. bars, usually equated to measurement in “atmospheres”;
The relationship between pressure units is as follows: 1 Bar = 100,000 Pa = 14.504 Psi.
If you have a mountain bike and it is difficult for you to decide what pressure is right for you, then at first you can use a special table:
|Cyclist weight (Kg)||Pressure
The pressure in the wheels of road bikes should be significantly higher, it varies between 6.5. 9 atmospheres (up to 130 Psi). The maximum value will be indicated on the tire itself.
It is also worth taking into account the air temperature outside: on hot sunny days, the air in the chamber heats up and, accordingly, expands, increasing the pressure in the tire, on cold days, everything is just the opposite. the pressure drops and you need to pump up the wheels a little more than the standard value for you.
The pressure in the wheels of a bicycle is a very important parameter, which affects not only the level of comfort while riding, but also the service life of important parts of the bicycle. Therefore, always make sure that the wheels of your bike are in good working order and inflated to the optimal level, taking into account the previously listed factors.