A lot of people obsess over their suspension settings and pressure, checking pressures religiously pre-ride. But the truth is that nothing will impact your bikes ride as much as having even 2psi variance in your bikes tires. Getting your tire pressure right goes a long way to having to having a fun, fast-flowing ride and staying rubber-side down. While the overall pressure range to consider is relatively small, finding that sweet spot can have a huge impact on how your bike performs.

Typical mountain bike pressures range from 22psi to 35psi, generally with more air in the rear than the front. This is because more of your weight is on the rear, so it needs more support. The exact pressure is determined by what tires you’re running, what terrain you’re riding, how aggressively you’re riding, and what the conditions are. There’s also a degree of personal preference: the best riders in the world can race to within fractions of a second of each other on different setups. They won’t vary by much – just a few psi, yet even 1psi can make noticeable differences.

Going soft?

While lower pressures are associated with slower rolling, in reality that’s only true on the smoothest surfaces. Why? Hard tires can’t deform around rough features, and are instead forced upwards, leaving the suspension and/or your body weight to absorb energy that would otherwise be powering you forward.

As well as dragging speed from your bike, wearing you out and making control more difficult, running too-high a pressure reduces grip. All this slows you down in ways that the simple ‘harder is faster’ theory just doesn’t account for.

At the other end of the scale, if pressure’s too low, e.g. under 20psi, wheel rims will be vulnerable to impact damage, inner tubes at risk of pinch-punctures (known as ‘snake bites’ for the parallel slashes they leave), and the tires prone to squirming sideways under hard cornering; over-soft tires feel draggy and unstable. If you’re riding very aggressively you may still find that tires start flopping on the rims and require similar pressures as tubes or the use of Tire Inserts. . . But Tire Inserts are a whole other topic!

Narrowing the range

For long distance and XC riding, rolling resistance is more important than ultimate grip because power output needs to be efficient. Plus, your chosen tires are likely to be light and relatively thin and flexy, so you’ll benefit from slightly higher pressures: think 28-30psi rear, 26-28psi front.

Going beyond 30-32psi on the rear and 30psi on the front is rarely beneficial on anything but the smoothest surfaces, especially if you need hard braking grip.

The rougher, steeper and more technical your preferred trails, the more outright grip becomes the driving force, and the lower your ideal pressure is likely to be. The traction, speed and control of tires that mould around roots and rocks instead of pinging and sliding off far outweighs any rolling speed lost on the occasional smooth spot, and it’s the same on the climb. Compliance and traction will get you further up technical climbs than nominally easy-rolling.

Under pressure

If you’re particularly large or heavy and find your tires squirm without higher pressures (mid 30s or above), swap to a tougher tire with a stiffer sidewall such as a DD Casing from Maxxis, or a Gravity Casing from Schwalbe. You’ll likely be faster overall with a heavier tire at workable pressures, than with a lighter one that’s too full of air. You will also feel more confident and comfortable. Confidence and Comfort translates into speed!

Closing Thoughts

Next time you head out with your MTB, why not take a pump and a pressure gauge, and experiment? If you only own a track or floor pump it is definitely worth investing in a digital tire gauge. It is not uncommon for floor pumps to be out by 5-10psi. This much pressure can make an extreme difference to your bikes performance. A cheap alternative to a digital tire gauge can be using your shock pump with a presta valve adapter to cross reference your floor pump readings.

Alternatively you can drop your bike in to the CB Cycles workshop for a free check with our digital gauge to give you confidence going forward.