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So, I've done 4 races this year with Stans Iron Cross wheels, setup tubeless with Clement MXPs.

I weight 167 and have start with 24/26 lbs and have progressively moved up to 32/34 lbs.  

Even this weekend, with 34 lbs in the rear, i lost enough air that I had to hit the pit to top off the tire. I measured the pressure post-race and my reading was 48 lbs- which exceeds Stan's 45 psi recommendation.   So at this point, it seem my options are to run 42/44, and try my luck again, or put a tube in the rear.   

Does anyone know if the 45 lbs limit applies when you run tubes in a Stan's rim? 

Anyone with similar experiences with Clement MXPs and tubeless?  Any other thoughts / recommendations? 



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There's a lot of guys on this forum who have more experience than me, but overall, I'd say you should be able to expect that your tubeless tires shouldn't be leaking much air, if any.  I'm running some WTB Cross Boss tubeless on HED Ardennes rims this year.  No issues.  None. Nada.  I'd add sealant, swirl it around, then dip the inflated tire into a tub of water to check for leaks.  If you can't solve the issue, head on down to your LBS, and good luck...

I weigh 160 and run mid to high 20s for psi. I am using Industry Nine Ultralight CX wheels. I have run tubeless in mtn bikes for years and in cross and gravel the last 2 years. I have run the mxp and mso and I would lose a couple psi over 4-5 days. It took me 3-4 days of setting them up to hold air for that long. It seemed to take 4 oz sealant per tire and constantly shaking and flipping them for the 3-4 days. I switched over to Vittoria and Specialized tubeless tires and they held air without sealant up to an hour and takes a couple weeks to lose a few psi after sealant. Tubeless specific makes life easier. I did burp the mxp before and never with the tubeless tires. Hope this helps.

Are you running tubeless specific Vittoria's? 

I've gone ahead and ordered latex tubes.   Pitting every race isn't a lot of fun and I can't imagine I'm saving that much time in the corners.  

thanks for your insight! 


They are the tubeless specific version.

Clement is releasing some true tubeless tires (think it'll be into 2016). The current gen don't seal up well at all.

Thanks for your response- I'm glad to know that I'm not the only one with this experience. 

Have had good success with the S-works 2blissCX tires and the new Schwalbe tubeless CX tires.

Take a look at the Specialized ones. They'll even hold air quite awhile w/o sealant and the tires are readily available.

So here's my follow up question: 

- Tires have 26 and 34 PSI in them today (haven't touched them since Sunday).  So I'm guessing that they're holding air. 

- If they're holding air, I thinking I must have burped them OR just became uncomfortable during the race and I felt they needed more air.  I didn't hear any air leaking (which I've certainly heard in the past).

Latex tubes I'm torn over whether to ride them hard (40/42 PSI) or put in tubes, which I'd ride hard anyway.  I suppose at this point I'll be running them so hard that the only benefit would be no pinch flats.   Any thoughts? 

They could have finally sealed properly. I would run low to mid 30s if you are still worried about air leaking. It shouldn't lose to much air during the 30-45 min of racing. 42 sounds like it will be rough and you will have less grip making the corners feel squirmy.

I've been using Iron Cross w/ Specialized Terra Pro 2Bliss and have been very happy so far (2 years) with no burps and holding air.

I've been inching down the PSI to see how low I can go.  I weigh 160 and ran 31 last week and rode a small set of stairs each lap, felt both rims hitting each time but had no issues.  Today was a grass crit and ran 29 but probably could have gone lower but was nervous to drop more than a couple PSI from previous races.

Your question on the max 45 PSI for the rims is with our without a tube.  I use my cross bike as my road bike and originally bought two sets of Iron Cross - one to set up with tubes/road tires and one tubeless for cross.

My LBS knew my intentions but didn't think it was going to be an issue but after reading some posts and contacting Stan's directly they confirmed the max was for any set up.


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