In this article, we use so-called affiliate links. With every purchase through these links, we receive a commission from the merchant. All relevant referral links are marked with . Learn more.
Tyres are the number one tuning part on mountain bikes and the only point of contact with the ground. They have a decisive influence on the riding experience and can completely unfold the performance of a bike or limit it horribly. That's why the correct tyre pressure is one of the most important parameters on a bike.
What is the effect of low tyre pressure on a bicycle?
A low tyre pressure provides more comfort, more traction and therefore safety. And the best thing is: as soon as you go off-road, the rolling resistance also decreases. What is already true for fine-grained gravel roads applies even more the rougher the surface becomes. According to a scientific study, 1.5 instead of 4 bar air pressure can save almost 20 watts on a grassy surface. Every bump eats up part of the drive power to lift the rider and wheel. Just as if you had to climb a small incline every time. With low tyre pressure on the bike, the tyres adapt better and the entire system has to be lifted less strongly and less frequently.
Which tyre pressure is the right one?
Car, motorbike, racing bike - on no other vehicle is the difference between tyre and rim width often greater than on a mountain bike. However, ever wider and yet lightweight rims between 25 and 35 millimetres in width are becoming increasingly popular. The effect: Instead of a bulb cross-section, a wide rim increases the support width of the MTB tyre. The tyre bends less under lateral load when cornering because the straight sidewalls of the tyre absorb the applied force better. The tyre pressure can therefore be reduced with wide rims.
The diagram provides a guide, but is by no means universally valid. In addition to the rim width and tyre width, the correct tyre pressure also depends heavily on the rider's weight, riding style and surface. Heavy mountain bikers with a system weight of over 95 kilos (rider weight including clothing/equipment plus bike weight) can easily run 0.2-0.5 bar more air pressure in their tyres than 65-kilo climbers on 9-kilo hardtails. Riding style and surface also influence the optimum tyre pressure. If your riding style is aggressive and the trails are very rough or covered with root carpets, you can use a little more air. If the pressure is low, there is a risk that the tyre will pull off the rim or that you will be constantly patching punctures caused by punctures.
How much bar is too much pressure?
The other extreme, which unfortunately can be observed again and again, is that people ride their mountain bike tyres at the limit, i.e. at 2.5 bar and more. This not only causes you to lose grip more quickly on bends or steep ramps with loose ground, but also causes you to "hop" over the trail, as the tyre no longer absorbs the shocks from the ground.
If you run your tyres tubeless with latex milk, you can generally also run a lower air pressure (0.1-0.4 bar less than with a tube), as there is no tube in the rim that can be punctured. As air pumps (Comparative test of 16 MTB floor pumps up to 50 euros) usually only display the air pressure inaccurately, you should use an air pressure gauge for precise adjustment.
