# Cyclocross tire pressure

#### FitSsikS

I was watching the 2018 UCI Cyclo-cross World Championships and one of the female competitors said she was running her tire pressures at 15 psi (she decided against 14). Of course women are lighter than men so.....I assume the men run their tires at a significantly higher pressure. Does anyone know what the typical pressure was on race day?
Thanx in advance. I don't know anything about cyclocross except that it's crazy hard....unlike the tires .

#### macbindle

Starting point tends to be bodyweight ÷ 10, then add 5 (in pounds). Obviously, if riding clincher you'll need to add a few more on top.

So my guess would be the rider in question weighs about 100lbs.

1psi adjustment (either way) is significant.

Essentially, you aim to go as low as you can without grounding the tyre on the rim. or having a tub fold.

#### FitSsikS

Thanks!
The internet has her weight at around 123 lbs so other factors (the conditions, course etc) made her go lower than what would be deemed 'normal'.

#### jmdirt

Body weight and preference certainly play a part, but...
The surface/course plays a huge part in determining psi/bar. Is it sandy, muddy, hard, hard-slick, rocky, grass, fast, slow, combo...
The tire itself (casing, compound, volume) can also play some part.
The rim can also play a small part in the equation.

#### lemon cheese cake

Re:

macbindle said:
Starting point tends to be bodyweight ÷ 10, then add 5 (in pounds). Obviously, if riding clincher you'll need to add a few more on top.

So my guess would be the rider in question weighs about 100lbs.

1psi adjustment (either way) is significant.

Essentially, you aim to go as low as you can without grounding the tyre on the rim. or having a tub fold.
https://bikerumor.com/2017/01/03/wyman-method-setting-proper-race-tire-pressure-part-1/
Another thing is the tyres they choose. For instance a mud tyre could be ran at a slightly higher pressure, as there is more grip due to more/larger nobbles, than an intermediate tyre that has a less/smaller nobbles. Also, if the majority of the course is mud, but a reasonably long section has large stones or tarmac you then have to ask whether it is worth raising the pressure to avoid flats for the former and increase speed for the latter but reduce performance/grip for the rest of the course.

#### Logic-is-your-friend

These guys ride with different tyre pressure every race. Body weight only plays a small part in that (because that should be relatively constant throughout the season). There are not many riders that get their tyre pressure right from the start, and often they will shout to their mechanics, to lower or raise the pressure of the tyres next time they change bikes during the actual race.

It's all about the course (corners, obstacles, climbs, straights), the surface (mud, sand, cobbles, risk of punctures), the weather (slippery, hard / soft dirt road), the type of tyre (in combination with all the other factors) and skill (where the rider feels most comfortably on the track in order to make his move or even where he feels least comfortable and is losing time), that all decides what tyre pressure they prefer. A rider that is proficient in riding long passages through the sand, will lower the pressure, to get more grip in the sand and not "sink" into the sand that much so he will be able to ride through the entire sand passage. A rider who is not good at riding through the sand, and needs to get off and run through the sandbox almost every time, will do good to RAISE the pressure in his tyres, so he can make up for the time he lost in the sandbox (where he has to run) on the harder parts of the track where he can get more top speed and burn less energy on higher tyre pressure (with the risk of crashing in a corner due to less grip).

It could be very possible that a rider like van der Poel rides with more pressure in his tyres, since he is technically superior to the entire CX peloton (save Meeusen perhaps), and can afford to take the same obstacles with more pressure, which in turn helps him save energy and get a higher top speed on other parts of the track. This is just a theoretical musing of mine, i'm not saying this is actually the case, but something like that could potentially be the case. Or maybe it's the other way around and maybe the more technically skilled rider decides to put even less pressure to be able to take time on certain obstacles even more (such as a sandbox or sharp corners) and ride away further in those sections.

For any certain race, a rider might prefer a different type of tyre, which in turn gives him better grip on certain parts of the course, which in turn allows him to put more pressure in the tyre compared to his rivals, which in turn raises the risk of getting a puncture, etc etc. Or the complete opposite, depending on weather, skill, and numerous other factors.

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#### Barkintheeye

Being new to cyclocross my impression is that you have to run somewhat higher tire pressure than if you're an experienced and seasoned cross racer. Weighing about 75 kg I am typically at around 25-30 psi (1.7-2.0 bars). Always racing on tubulars so maybe I should be able to always be at 25 psi but the sensation of bottoming out on hard edges, roots etc is not great and makes me uncomfortable. I have never punctured so maybe I am just at a too high pressure?

Not knowing exactly what the pros are doing my guess is that a 75 kg rider could and would opt for a pressure of around 22-25 on a course without any major nastiness (sharp edges, roots and big barriers) but it would be interesting to have more "inside" info on this. A good tubular (Dugast etc) will not become squirmy in corners despite being run at very low pressures. Some tires however respond poorly to low pressures giving you the sensation of coming off the rim.

#### Logic-is-your-friend

Being new to cyclocross my impression is that you have to run somewhat higher tire pressure than if you're an experienced and seasoned cross racer.
I actually think it's more the other way around, because more pressure means less grip. Less grip is probably the last thing you want as a newbee.

#### lemon cheese cake

Being new to cyclocross my impression is that you have to run somewhat higher tire pressure than if you're an experienced and seasoned cross racer. Weighing about 75 kg I am typically at around 25-30 psi (1.7-2.0 bars). Always racing on tubulars so maybe I should be able to always be at 25 psi but the sensation of bottoming out on hard edges, roots etc is not great and makes me uncomfortable. I have never punctured so maybe I am just at a too high pressure?

Not knowing exactly what the pros are doing my guess is that a 75 kg rider could and would opt for a pressure of around 22-25 on a course without any major nastiness (sharp edges, roots and big barriers) but it would be interesting to have more "inside" info on this. A good tubular (Dugast etc) will not become squirmy in corners despite being run at very low pressures. Some tires however respond poorly to low pressures giving you the sensation of coming off the rim.
Tyre pressure is personal preference. However, given you are racing on Tubs, I'd say you can run the pressures a bit lower. As Logic says above, if anything you probably want a lower pressure as you will have more confidence to push in the corners. Obviously there isa trade off for speed there though. If the course is rooty or stoney you will want a higher pressure than a completely smooth course, so if it was a really muddy course but with a large amount of roots, you will probably be able to get a way with 20 psi. If it is completely smooth but has alot of corners, the top riders who are liighter have been known to go as low as something like 12psi.
Tubular tyres (especially the cotton or silk cased ones) will have a much higher thread count than that of a clincher/tubeless. This allows them to be much suppler than the standard clincher. Because of this, most of the pros still use them because of the advantage that they will deform over roots and stones much better than a tubeless tyre. The obvious advantage of tubeless is they are virtually self sealing, however, its a long run to the pits if you get a large slice in them or burp them and unseat the the tyre. As they will still leave a cushion between rim and ground, and hold their shape riders can still ride them when flat and limp back to the pits.

#### Barkintheeye

I actually think it's more the other way around, because more pressure means less grip. Less grip is probably the last thing you want as a newbee.

Maybe this is just me, but when you're new to the sport you'll make more errors such as hitting smaller and larger obstacles, not being sufficiently "light" on the bike (i.e. just sitting too heavy on the saddle) and the risk is significantly higher that you'll get a puncture from those mistakes. Therefore I tend to go with slightly higher pressure. Obviously that can be good for the roll on easy parts of the track but it is clearly disadvantageous in corners and slopes where you need a grip. I tend to "fix" the grip by opting for a more defensive choice of tyre, e.g. when pros would ride Grifos/Typhoons I would probably go for Rhinos etc.

I question that the pros typically opt for higher pressures (25-30 PSI) just to have better roll but it would be interesting to know. Obviously track conditions, weight, riding style and tyre are all different but like for like I am pretty sure I am at a too high pressure than a more able CX-rider would be - just to be sure to avoid puncture.

#### Logic-is-your-friend

Mathieu stating in the post race interview today, that due to the course (terrain/weather), that he chose to ride with more pressure in his tires than in other races because it would be a fast course. That also meant more impact on his back riding over bumps and rough parts.

#### Barkintheeye

Did they say what pressure he was riding at?

Last year at the World Championship in Bogense Denmark - a very fast and relatively dry track - the commentators said that the Pros were riding at PSIs below 20. If that’s correct it is really very low. I have tried that tire pressure with several different tubulars and with clinchers and inner tubes and I am feeling the rims despite being relatively slow.

#### lemon cheese cake

Did they say what pressure he was riding at?

Last year at the World Championship in Bogense Denmark - a very fast and relatively dry track - the commentators said that the Pros were riding at PSIs below 20. If that’s correct it is really very low. I have tried that tire pressure with several different tubulars and with clinchers and inner tubes and I am feeling the rims despite being relatively slow.
Despite being fast and flat, it was also quite slippery on top due to the frost on the ground which then started to melt throughout the day. I think it's Cody Kaiser who talked on his Youtube channel about different pressures and treads on different practice sessions of the world championships.

Barkintheeye

#### Barkintheeye

I will look it up to get the exact quote but the point is that the pressure mentioned is not for the everyday CX rider to manage (despite being optimal for those that could handle it). It gives lots of grip even with tires that have medium (Typhoons) or little (Dunes) threads/patterns which is nice but I am bottoming to the rims too often to get comfortable despite being quite slow. Going down steep sections and coming off of steep drops just wouldn’t work for me. Possibly tubulars can take it but it feels like it’s going to end up bad. At around 25 PSI is where my comfort zone is.

#### Logic-is-your-friend

I will look it up to get the exact quote but the point is that the pressure mentioned is not for the everyday CX rider to manage (despite being optimal for those that could handle it). It gives lots of grip even with tires that have medium (Typhoons) or little (Dunes) threads/patterns which is nice but I am bottoming to the rims too often to get comfortable despite being quite slow. Going down steep sections and coming off of steep drops just wouldn’t work for me. Possibly tubulars can take it but it feels like it’s going to end up bad. At around 25 PSI is where my comfort zone is.
Your personal weight also plays a role ofcourse.

#### Barkintheeye

75 kg ”dry weight” and just below 85 kg fully kitted and bike. Should be about the same weight as some of the larger pro riders.

#### lemon cheese cake

75 kg ”dry weight” and just below 85 kg fully kitted and bike. Should be about the same weight as some of the larger pro riders.
If we follow the Helen Wyman method for tubs of mass in lbs divided by 10 then add five, that's 165lbs/10 equals 16.5. Add 5 that's 21.5 PSI to start with. (1.48 bar)

For clinchers, we divide by 10 then add 10, so 165/10 = 16.5. Add 10 to get a starting pressure of 26.5 Psi. (1.83 bar)

Start off with those pressures and then adapt appropriately for riding conditions. I.e increase the pressure at 1 psi (about 0.007 bar) intervals if you feel you are bottoming out, or decrease at the same rate if your sliding around in the corners. It's a system that works well for pro riders, and does so for me as well.

#### Logic-is-your-friend

Adrie just said during a race-interview in Essen, that they had to lower Mathieu's tire pressure during the race because water started coming up out of the soil, and the track became more slippery.

#### lemon cheese cake

Adrie just said during a race-interview in Essen, that they had to lower Mathieu's tire pressure during the race because water started coming up out of the soil, and the track became more slippery.
I guess that's why he punctured then possibly?

#### Logic-is-your-friend

I guess that's why he punctured then possibly?
No, Essen was the race before last. I don't think he punctured in Essen.

Van aert said yesterday that he started with too little tire pressure, which is why he had to change a few times, and made some mistakes in corners. He said he started with 1.35 bar, which was a bit on the low side for his weight. 1.35

#### Barkintheeye

No, Essen was the race before last. I don't think he punctured in Essen.

Van aert said yesterday that he started with too little tire pressure, which is why he had to change a few times, and made some mistakes in corners. He said he started with 1.35 bar, which was a bit on the low side for his weight. 1.35

That is crazy low. At around 1.8 bar I start to feel the ground hitting the rims with Dugast tubulars. Obviously Wout has a tonne better technique but still how does he manage???

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#### lemon cheese cake

No, Essen was the race before last. I don't think he punctured in Essen.

Van aert said yesterday that he started with too little tire pressure, which is why he had to change a few times, and made some mistakes in corners. He said he started with 1.35 bar, which was a bit on the low side for his weight. 1.35
Oh yes! Helps if I read which race this was!
Van Aert definitely seemed more settled from about half way through, the descents especially on the second part seemed to be taken with greater confidence. If anything, I'd say he was carrying more speed and momentum through the corner after the steep bumpy downhill than Van der Poel.