Tubeless cyclocross tire pressure

[Pompom]

I plan to race tubeless tires for cyclocross this season.

I setup my wheels (dtswiss rims with Donnelly MXP tires using orange seal) and they feel good but I have no idea what pressure to run. I am an experienced cx racer and know that pressure is all about rider weight, course conditions, tire type and voodoo but I’d love to hear others’ experience on tubeless. I weigh 153 lbs and ride northeast / New England style courses.

CX riders please chime in: what rims/tires do you run and what kinda pressure are you pulling? Please be sure to add your weight if your not too shy.

(note: Pleas don’t turn this into a discussion about tubulars. I’m already there. )

[catchourbreath]

I usually run my tubeless maybe 5-10 psi more than my tubulars(anywhere from 15-25psi). Probably over doing it but I've burped when they were around 20 psi but not fully flat just lost some pressure. I race NE and weigh maybe 5 lbs more. That'd be on Paradigm Comp rims on 32c CX0 tires in the past.

[kppolich]

Go tubular, it'll only take 1 or 2 races where you burp the tubeless tire and DNF.
I was in the same boat as you were, tubulars for CX for lower pressures. Tire beads/rims aren't there yet for CX beating without burping.

When I did run tubeless MXP or PDX depending on course I was at 29R/26F. 6'0 155lbs racing SSCX

[ikecycke]

I've been on tubeless for the past 4 CX seasons, anywhere from 8 to 15 races per year, and have never burped a tire to the point where I couldn't finish a race.

Nextie carbon rims, 21 mm inner width. I've used 33mm MXP and PDX for multiple years, and tried the Challenge Grifo Race last year with good results.

Weight of ~160 lbs, I would typically run 22f/24r, but honestly think that's a bit low. I race in Texas where it's usually dry and fast, but found myself getting a bit squirrely on turny courses. I've also bottomed out enough on features to the point that I cracked a rim, so a bit more pressure likely would have prevented that.

[crankles]

Originally Posted by kppolich

Go tubular, it'll only take 1 or 2 races where you burp the tubeless tire and DNF.
I was in the same boat as you were, tubulars for CX for lower pressures. Tire beads/rims aren't there yet for CX beating without burping.

When I did run tubeless MXP or PDX depending on course I was at 29R/26F. 6'0 155lbs racing SSCX

I use to be all tubular like kppolich, But now I'm now I've 'semi-swicthed' running two wheelsets. Tubulars with a mud tread for races that really need 15psi and a set of Tubeless running MDX or a file tread at 25-30. Last season I did maybe 14 races. 12 on the tubeless. One bike is running a set of eastons, the other some lightbicycle rims. I run a variety of tires on the tubeless. MDX and even some specialized triggers. I've only burped the eastons once when I smacked a rock. Lost abotu 10 psi, but rode to the pits.

While I think nothing beats a tubular mud tire @15psi, The tubeless is a nice compromise for a lot of courses, with the ability to swap tread easily. Race weight is around 160lbs ( fingers crossed...harder to drop pound once I hit 55)

[eippo1]

Originally Posted by ikecycke

I've been on tubeless for the past 4 CX seasons, anywhere from 8 to 15 races per year, and have never burped a tire to the point where I couldn't finish a race.

Nextie carbon rims, 21 mm inner width. I've used 33mm MXP and PDX for multiple years, and tried the Challenge Grifo Race last year with good results.

Weight of ~160 lbs, I would typically run 22f/24r, but honestly think that's a bit low. I race in Texas where it's usually dry and fast, but found myself getting a bit squirrely on turny courses. I've also bottomed out enough on features to the point that I cracked a rim, so a bit more pressure likely would have prevented that.

You might look into a tire insert that would help for bottoming out. I have Tannus inserts in my gravel wheels and they're great for when I miss a rock etc.

[Alistair]

I'd start around 28psi and drop from there. Probably end up in the 23-25psi range.

[tribarbet]

In my opinion if you’re racing on conditions that are not generally dry and fast where you can get away with higher pressures, I would suggest to stay away from tubeless for cross.

I bet that you have a higher chance of burping a tire on a tubeless setup, than a pinch flat with latex tubes.

I’m 138 lbs. I run tubulars and do 18f/20r psi and with clinchers (21mm internal) with latex tubes I do 20f/22r or 21f/24r psi and have never had a pinch flat.

I wanted to do tubeless, but a master mechanic whom I fully trust told me to not waste my time, and that I will be surprised on how low I can run them with latex tubes. He was not wrong.
I see people burping tubeless all the time and in the meantime I’m finishing all my races with my tubulars or my clinchers.

[polyhistoric]

8 years racing CX in NE (50+ races). 1/2 on tubes/clinchers and 1/2 on tubeless. I've burped to a flat and needed a wheel change only once with tubeless and never pinch flatted a clincher. I'm 143 and running either Am. Classic hurricanes or I9 UL235 with donnelly or vittora tires. Generally I end up a little higher in pressure, starting at 30f/32r and dropping to 26-28 range for race. I tend to right light (thanks BMX) and try to avoid nailing any course "features"

I have never felt that secure dropping under 24, and the extra squish doesn't give me any appreciable advantage.

[catchourbreath]

Not sure where you are but east coast local races are filled with roots and rocks, pinch flats are a pretty common sight; even traditional tubulars see it fairly regularly. Tubeless even 5 years ago is worlds different than now in terms of ease and usefulness. I'd still shy away from sub 20 psi but you can comfortably rail corners at speed in the mid 20psi range.

[benb]

CX is limited to 33mm?

These are crazy crazy low pressures whether tubeless or tubular. They have got to be well below the minimum safe pressures the tire manufacturer and rim manufacturer list right?

I'm not saying don't do it, I've spent a lot of time doing the same with MTB tires. Lots of time running 15-20psi in the front and 20-25psi on the back on tires that said 30psi was the minimum. But relatively speaking what I was doing was nowhere near as low as what's being discussed here, those were 2.2-2.3" tires. 30psi would have been utterly useless with that setup unless you weighed 250-300lbs.. I'd have been bouncing out of control off of everything and losing lots of traction.

Getting almost into fat bike territory with a 33c tire is amazingly low. Are CX riders experimenting with the foam inserts like MTB?

[EB]

Originally Posted by benb

CX is limited to 33mm?

Only in UCI races, which I presume (perhaps incorrectly) that nobody here is riding.

[Alistair]

Originally Posted by Eli Bingham

Only in UCI races, which I presume (perhaps incorrectly) that nobody here is riding.

This. Here in DC, the limit only applies to the elite/pro fields at the few UCI points events (Charm City, etc). The rest of the race aren't for UCI points, so the limit isn't applicable. That said, I've usually raced on 32-33mm tires since that was available and didn't see the need to go wider/heavier. I haven't raced much the last 4-5 years, and with the proliferation of gravel tires, I might be better off on 34-38mm tires. Dunno.

[benb]

OK so it's more MTB lite, which is what the CX race(s) I tried were in the low levels too back in the day.

At some point it was like the CX bike was a style thing. A MTB was much more capable and was allowed in the lowest levels. That was back in the Canti days though.

There was a period there where MTB had "short track XC" and it seemed like they were pretending it was CX. And CX was pretending it was XC. And the same people seemed to be winning both at the elite level.

[Alistair]

Originally Posted by benb

There was a period there where MTB had "short track XC"...

They still do. Every UCI XCO event has a XCC (short-track) event as a qualifier that sits the front 3 rows of thee XCO event.