Tubeless tyre pressures - what do you ride?

I'm about 85kg kitted up for the ride, maybe a couple kg less now.

I run NN front, RR rear, both 2.25 and tubeless and on a 5" travel endurance race bike (Cannondale Rize). I run mine at 22-25psi front and 28-32 on the rear.

Any less either end and it starts to get squirmy, any more than 25 and the NN's get skatey. With Maxxis Ignitors 2.35 / Larsen TT 2.0 combo I used to run 28-30 in the front and 28-32 in the rear and found this combo and pressure very good in most conditions.

Pressures depend on trail conditions. If it's smooth and groomed I run higher pressure on the rear, if the surface is rougher or dusty and loose I run lower unless squirm becomes a problem and then I start to lift it again. Front pressure I don't change much.

And the biggest factor in your question is what datum are you measuring the pressure against. A recent thread highlighted the fact that pump gauges often vary in reading between brands by large margins.

After years of playing around with tyre pressures, and not really listening to what others suggest, I think it comes down to what feels and works best for your particular circumstances. Pick one device, then calibrate (or compare) all your pumps and gauges against that so you can repeatably set pressure on the go, or know where you are relative to the base line when experimenting... Or if the budget allows, get yourself one good quality portable pressure gauge and use it for everything.

That comes with experience, though, and a bit of an analytical brain. Some of my experience has come from making mistakes (eg, not topping up before a ride) and find out that it was better in some circumstances, and not so good in others, and then being curious and measuring.

A lot of beginners don't know what "good" should feel like, so it's a bit hard for them to judge whether a change is an improvement. heck, after 6 years I still don't know what "good" feels like. I would need to ride a "good" rider's bike who is the same weight as me to get a feel for it.

I have to admit once I find something that works I tend not to vary it too much. I have a digital gauge. It seems to be consistent with my other analog gauges on other pumps so I'm happy to call it accurate.

Would someone else like how my bike behaves? Probably not, but I have no idea.

Hi All,

Thanks for your comments.

I understand what you mean when you say 'what feels right for you', obviously 20psi was far to low but still it didn't seem to have that much (negative) effect and it really did grip! (the tyre is a Snake Skin so it is a little stiffer)

I used to run the same tyre with tubes at about 32-34psi so I might start experimenting around the 26-30 mark and see how I get on.

I'm using a cheap BBB floor pump and I reckon the gauge is probably not that accurate and 10psi increments are measured over about 5mm, so it's pretty hard to tell where you're at with the pressures.

Does anyone have any suggestions for a floor pump with a MTB specific gauge? I had a look at a specialized one today which only went up to 70psi and it was much easier to see the incremental steps in pressure. Instead, I guess I could invest in a decent stand alone gauge however I have a car one which would be perfect for the job but I doubt I could modify it to fit on the valve stem and achieve a meaningful reading.

What pumps/gauges work well for you?

If you can't squeeze the tyre using your thumb, or the depression it makes is barely a depression, you're out of range. If you get that opposable thumb touching it opposite, you're out of range.

What's left is your goldilocks zone. Unless you have huge 2.5+ hoops, keep dropping the pressure till you bottom out on the rim too often. I've ridden with some DH riders that run 10psi with rock solid rims - they've always got grip. On my XC bike, I run 2.3's at 18psi and only occasionally bottom out but it isn't a problem as I run carbon rims (they don't dent like my Al rims used to).

Apologies, should have mentioned:
I'm in WA where we ride on ball bearing gravel.
I weigh around 70kgs with a 11kg bike.
I run rims that have a flat section adjacent to the tyre bead hook before dropping into the spoke channel so burping isn't an issue (never had it burp, even at 15psi doing 1m drops off balance).

Im around 78kgs & run 18-20psi front & 23-25psi rear when I'm riding single track & want grip.
This is with Maxxis Ikon EXO 2.2 on Easton EA XC 90 UST rims on a 29er HT (10kg).
Never burped the tyres that I know of.

When riding firetrails ( eg Loftus RNP ) ill bump it up a bit to 23-25psi front & 30-32 psi rear.

On my 29er dually with Nobby nicks snakeskins i run 20-22 psi front & 28-20psi rear on Stans Crests.

If your riding centre track and duck holes they are so rocky that its worth running a few extra psi to keep your rims in one piece. Lower pressures are reasonably dependant on tyre width. You didnt mention what size tyres however lower pressures will roll more efficiently and provide better traction than higher so lower is better, and you can go lower with wider tyres. On a 5" dually you should be on 2.25s, not 2.1s.

I have been running 20 or 22 psi at stromlo recently without any issues although I am a bit lighter than you. I expect most of the elites here at the xco nationals this week will be running pressures lower than I do.

Your mileage may vary.

Lach tend to disagree about rolling resistance and tyre pressure/grip. These links give some research results.

http://www.mckramppi.com/en/bike04rengas/Bike200... (some caution in interpreting this data is needed)
http://www.mtbonline.co.za/info/mtb-tyre-rolling...
http://www.schwalbetires.com/tech_info/rolling_r... (this article by Schwalbe has a table indicating the rolling restance of some of their tyres - but it may need updating)

To quote extracts from the articles:
"Off-road a reduction of tyre pressure reduces rolling resistance. In a meadow for instance going back from 4.0 to 1.5 bar (57 to 21 p.s.i.) can save remarkable 18 Watts of power."

"On an identical course and at exactly the same speed, the widest of the tyres tested here at 1.5 bar (21 p.s.i.) requires a solid 50 W less power than a narrow tyre at 4.0 bar (57 p.s.i.)."

another:
"The research team found no significant correlation between the grip and the rolling resistance of the tires"

"Anyone who wants to ride really fast off-road needs to decrease tyre pressure"

Articles list the tyres in order of rolling resistance (and grip)

Another article claims “- - - a bicycle with narrow tires is much easier to accelerate because the rotating mass of the wheels is lower and the bicycle is much more agile. At constant speeds of around 20 km/h, the ride is better with wider tires. In practice, the energy saving is even greater than in theory as the elasticity of the tires absorbs road shocks, which would otherwise be transferred to the rider and so saves energy.”

Choose a tyre to match your conditions, riding style and you have confidence in. Lack of confidence in tyres will result in slower riding.

FWIW - I'm in WA ride a 29r, currently specialized 2.2 wide, and ride between 22 and 25psi. But I'm relatively gentle on tyres (and slow!).

I admit I probably simplified the argument a bit too much. There are obviously differences related to the structure / compound of the tyre which impact on both grip and rolling resistance.
And it seems that the research supports a view that less pressure gives better (less) rolling resistance off road. Although measuring it on a meadow is hardly a typical off road surface. If I was riding in a meadow or on beaches or snow all the time I'd want a Pugsley with low pressure tyres. If I was riding mostly hard-packed fire trails, it would be a different story. Interesting to know whether having full suspension would reduce some of the energy disadvantage of higher pressures on uneven surfaces.
Anyway, I still think it comes back to what sort of riding you do as to whether higher or lower pressure is best for whatever combination of tyres, bike, terrain and riding style you are looking at.

I'm probably 5kg less UglyBob.
Using 29x2.30 tyres, I run the front between 15-18 and the rear a couple psi higher. 15psi is the very limit for my rim/tyre combo - I use 30mm wide rims which again, reduce the pressure you need to run.

If I were running narrower tyres, I'd up the pressure a fraction right in that range of 20-25 that you suggest. Really, the best way to find out is to keep dropping them and see where the tyre hits a sweet spot (might cost you a dent or two in the rim). You'll know it - seriously - the tyre will sound different.

Instead of the usual chattering, on, off sound of the tyre on the gravel, it will be a smoothing rolling shhhrrrr because the tyre will be in contact with the ground at all times, which equals more grip. Of course, according to Lach, each time your tyre isn't in the air, that's a rolling resistance penalty for you, but I'm sure you can live with that.

p.s. don't worry about trying to find grip though - it's not there at the KC. Well, not on the trail it isn't. The grip is in the secret berms - tree trunks, ruts, anything that's surface is not horizontal is a berm. You might be surprised at this, but I run the Specialized Renegade tyre (slick with pimples) and have no problem keeping up with (apologies for the lack of modesty) some pretty fast characters. I lose out slightly in flat corners (with no secret berms) but they are few are far between.
http://www.specialized.com/us/en/ftb/mtb-tires/c...

thanks Martin. might try drop it to mid 20's this weekend, see how i go!

i'm running a nice fat hans dampf on the front at the moment, but have a renegade on the rear.

correct though re grip - not much to be had at the moment. looking like a bit of rain in the next few days, so hopefully some makes it out to kala for the weekend eh!

Depends - can be anything from inches deep so that its up to the rim in some sections and no base, or it can be just one layer thick over hard base. Part of the problem can be the 'hard base' is composed of very fine grains and is unstable and contains more peas, so riding it just exposes and loosens more peas, so in some cases a 'cleared' line wont appear.

But after rain (and it hasn't rained for some time) the soil can compact or the fine dust is washed away, so its then probably the best grip we'll have.

I've got to where I am (such as it is) without power meters, heart rate monitors, or any understanding of science it seems, so I'm happy to rest on my laurels for another 12 months

In the meantime, to demonstrate that an aged mind can still be an open mind, I'll probably experiment with tyre pressures when I convert to tubeless ahead of an upcoming Central Australia trip. If only because I expect that the riding conditions there may just be a bit different to Sydney....

Arrh! Beware the three-cornered jack! Take lots of sealant, and maybe consult a bike shop in the area for suggested tyres.

I wouldnt do the Alice event without tubeless conversion.
It would be mad.
FWIW I went all week without a single puncture on tubeless Ignitor/Crossmarks.
The locals there believe Continentals are better suited to their trails and tend to push those.