If there’s one change to equipment that makes more difference than any other, it’s playing with the pressure in your tyres. Particularly so with tubulars but also with clinchers and tubeless. Tyre pressure is known as a bit of an art rather than a science, hence it’s inclusion in our Mud Arts section. There is no one formula for pressure – everything depends on tread, carcass design on the tyre, conditions under the wheel, rider style, rider weight, temperature, the inner tubes in the tyre etc etc etc.
Watching pro riders playing with their pressure in warm up laps, before the start and even mid race by barking instructions at their mechanic in the pits, you quickly perceive there is a lot of ‘feel’ involved in this and not a lot of science. And with the slightly intangible but hugely important ‘feel’ comes the necessity for experience. In this guide to tyre pressure we can give you the basics, but you will have to go out there and build up your experience yourself.
Clincher tyres, where the tyre has a bead to hook it onto the rim, are a popular and cost effective way of equiping your ‘cross bike. With the ability to change tyres on a single wheelset relatively easily, and fix punctures cheaply. many riders are happy not to look beyond clinchers for both their training and racing needs. Clinchers need to be run at higher pressures than their tubular counterparts in order to avoid pinch punctures from small rocks, roots and sharp edges.
We recommend starting out with a pressure of around 35psi (2.4bar) and seeing how that feels. If where you are riding has no obvious pinch puncture hazards, then drop the pressure slightly to a point around 30psi (2bar). Whilst lighter riders may well be able to go lower than this, especially with practice, the puncture risk can increase considerably below 30psi or so. Latex inner tubes may also help you reduce your pressure, but reduce the risk of pinch punctures.
As you begin to progress with your cyclocross career, you will probably come across more and more riders talking furtively but evangelically about tubs, tread choice, glue jobs and pressure. Like a cyclocross-themed Dark Arts convention, the language and techniques involved in running tubulars for ‘cross can seem daunting, even mystical but the advantages gained from gluing on a set of tubulars onto a concave rim, hoping they stay on and then caring and cleaning them after each race like your first-born, are significant.
Essentially, tubulars can be run at much lower pressures than clinchers, and lower pressure = a greater contact patch = greater grip.
We start with the pressure at 30psi (2bar) and work down from there. Depending on your weight, riding style and confidence in your glueing abilities, you should be able to get down to the low 20s, assuming the surfaces you are riding on are uniformly soft. But, riding at these low pressures takes practice so don’t jump in straightaway – find a smooth grassy surface and play with letting air out till you feel the tub is almost folding over or squirming too much. It’s all about building up that experience over time. Top riders can seemingly notice differences of 1psi or so in their tubs, according to the changes in grip and performance. See how far you can get with it…
Check your pressure
There are a number of ways of checking the pressure in your tyres or tubs. Mechanically, you can use a track pump which may, or may not be accurate to within a few psi. Always use the same pump for reference as calibration may well change between pumps. More accurate is a digital tyre gauge, one that will do fractions of a psi/bar rather than 10s..
But perhaps the best way to reference and adjust your pressure is with your hands. Simply place the thumb of one hand on the top of the tread, and push down with it with the palm of your other hand. Over time you will build up a reference point from the feel of the tire on your thumb, and cross reference that with the feel of tyre when riding.
See below for technique.