Like any vehicle, the tires of a mountain bike are the only component in direct contact with the ground. They have a dual function, grip, and an additional shock absorber. In other words, they are of fundamental importance.
To enjoy a smooth ride on your bike without fearing a flat tire, you need to know how much air pressure is correct for you. In this article, we’ll explain why you should keep track of your tire pressure and what you can do to improve it.
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Knowing the Right Tire Pressure for Your Mountain Bike – The Complete Guide
But what you should not lose sight of is that even the best tire, whatever the brand, loses a large part of its qualities if it is not inflated to the correct pressure.
So how do you know the right tire pressure for your mountain bike? It is what we will see point by point in this article.
The Criteria to Take into account to inflate your mountain bike
The weight of the cyclist
As with any vehicle, the weight supported by the tires is an essential element in determining the correct pressure.
The weight exerted is a significant constraint for the tire, and its level of inflation will largely determine its behavior, in particular during impacts:
- Too much weight with under-inflated tires can significantly impact climbing performance and efficiency.
- In the case of too much pressure, the risk is downright the bursting of the tire.
Furthermore, it is worth noting that the weight exerted is higher on the rear wheel; the pressure must be higher at the rear than at the front. It is usually a difference of 0.1 bar.
Here is a table summarizing the ideal pressures according to your weight:
The Type of Tire
What is referred to as “the type of tire” corresponds to the latter’s technology. In all, there are three main types of tires; here they are:
- Tubeless Ready: This is a tire without an inner tube containing preventive liquid. Generally latex-based, it is used to seal the tire in the event of a puncture.
- Tubeless: This type of tire is quite similar to its previous design; it also has no inner tube. On the other hand, it has a waterproof inner liner that acts as an inner tube, making it heavier than its Tubeless-ready counterpart.
- Tubetype: Probably the type of tire we all started mountain biking, equipped with an excellent old inner tube.
Due to their particular design, tubeless and Tubeless Ready tires can run at very low pressures, around 1.5 bars. Specific pumps also exist primarily for the occasion.
Tubetype tire pressure should never drop this low. The acceptable minimum is 1.6 bars, with a person weighing only 50 kilos.
There are then 3 mountain bike tire sizes expressed in inches:
- 26 inches
- 27.5 inches
- 29 inches
It is believed that, as a general rule, the smaller the section of the tire, the higher the pressure must be. Knowing that, in general, the area is proportional to the diameter, the average pressure should be:
- approximately 1.8 to 2.2 bars in 26.”
- between 1.9 and 2.3 bars for 27.5.”
- between 2 and 2.5 bars for 29″.
Remember that these are average pressures that can vary according to other factors, including the cyclist’s weight, the practice, the type of ground, and the technology used.
Usage and Terms
The discipline practiced, and the nature of the ground are essential elements to consider.
First of all, for all the disciplines during which your tires would have to undergo violent shocks with stones, roots, tree trunks, etc. It is essential to maintain a relatively low pressure because of the risk of bursting.
It is particularly true with DH, Enduro, or Freeride practices, but also to a certain extent for XC and All Mountain.
For these disciplines, we recommend an average pressure of 1.3 bar at the front and 1.5 bar at the rear (with Tubeless or Tubeless Ready tires).
Opt for inflation of 0.2 bar to 0.35 bar in addition to the pressures above with an inner tube.
You might even want to consider slightly lower pressure on really rough terrain for the more extreme rides on this list, like DH or Enduro.
And finally, as we saw above, you will also have to consider the section of your tires; the more significant this is, the lower the pressure (within reasonable limits).
Now let’s come to the type of terrain. Here, if there were one rule to remember, it would probably be that the more complex the ground, the lower the pressure should be, and the average pressure should be soft enough to absorb shock on a rocky, brittle basis.
Conversely, on rolling ground, higher pressure allows for better performance.
Finally, we will address the issue of weather conditions. The principle that applies here could not be more straightforward, and the pressure must be higher than on the wet ground on dry ground.
On the slippery ground, but even more so, muddy, an overinflated tire loses traction and grip.
The Risks of Improper Tire Inflation
In either case, improper tire inflation can have serious consequences, affecting your performance, tire wear, and even your safety.
Let’s see the different scenarios.
The Under-Inflation of the Mountain Bike
A reasonably underinflated tire has better shock absorption and increased traction in wet conditions. On the other hand, excessive under-inflation of the tire will no longer play its role as a shock absorber.
In this case, your rim will absorb the shocks and you simultaneously. The edge risks undergoing deformations and the tire abnormal wear or even bursting in the long term.
But before that, you also risk suffering a noticeable performance loss, mainly on rolling and dry ground.
Finally, the higher the cyclist’s weight, the more the under-inflation will be felt both in terms of performance and damage.
Overinflation of the Mountain Bike
Be careful not to fall into the opposite excess with over-inflated tires.
Here the significant risk is the bursting of the tire in the event of impact with an obstacle or landing on hard ground. Rider comfort will also be compromised as too-hard tires no longer absorb shocks.
Finally, as we discussed earlier, over-inflation is particularly detrimental to greasy and muddy terrain grip.
To protect yourself from either of these scenarios, try to keep everything you need with you on your outings, both for inflation and repair.
Find the ideal pressure for your mountain bike tires.
The ideal pressure for your mountain bike tires is a compromise to be found between all the elements mentioned in this article. That’s to say :
- the weight of the cyclist,
- the type of tires,
- the practice,
- weather conditions.
We can even add a parameter not yet mentioned: the pilot’s preference and feelings, which are subjective.
Finally, the last point, pay attention to the confusion that may exist with the pressures indicated on the sidewalls of your tires. Generally marked with the initials PSI, these are only minimum and maximum pressures given as guides and not ideal forces.
This article is coming to an end; we hope it has been helpful to you and that now your tire pressure has no more secrets for you. Tire pressure is crucial for your performance, comfort, and safety, so don’t neglect this aspect.