Slow Air Leak from Shimano Dura Ace Scandium Wheels with Continental Tubeless Tires


New Member
Jun 5, 2011
I've recently bought some ex-demo Shimano Dura Ace Scandium wheels with Continental tubeless tires to go on my Tri bike and have a curious problem. I pump my tires up to 100 p.s.i. as standard and air seems to leak out of the front wheel at a much faster rate than from the rear wheel, until the pressure drops a little and then the rate of air escape is much reduced. I guess there's a small gap somewhere in the sealant in the front wheel, but how to fix it? If I take the wheel back to the LBS where it came from, they'll put some sealant gunk in it and give it back to me, that'll no doubt solve the problem, but will make it a horrid mess to change tyres in the future - which I really really don't want!!! Does anyone know how I can sort this wheel out without resorting to sealing gunk? I'm a bit wary of messing with tubless tires, as I've heard they are easy to damage. Brilliant wheels and tyres by the way. Would really recommend them.
So you're running your tubeless setup with no Stan's, Caffe, Hutchinson or other sealant? Are they supposed to work properly without sealant?

I ran tubeless cross tires for a couple of seasons before switching to tubulars and I always ran sealant. I'd be surprised if you can get a reliable dry seal at road pressures and you certainly lose any advantages the tubeless setup might give you for thorns and small punctures if you run them dry. But I've never run road tubeless so maybe that's what folks are doing, lack of flat insurance and all.

Personally I'd squirt an ounce of Stan's sealant possibly mixed with some of the Hutchinson sealant (my favorite cross sealant blend) into each tire with the Stan's injector. Yeah it can make tire changes messier but also much less frequent as the sealant helps avoid run of the mill flats.
Thank you, I think you clarified my thinking for me......I went to the bike shop and got it sorted.
Running sealant is mandatory, you have to do it. I was running the tubeless setup with Ultegra wheels but flatted the rear, sprayed gunk all over the place, and had to replace the tire anyway.

I went to a tube-type setup and it is lighter than the tubeless and handles better. I didn't really care for the tubeless tires. Running Conto Ultra Gatorskins (wire beads!) and very lightweight tubes; the bike handles brilliantly now.
My Contis run really well now too, definitely grippy and absorb bumps well with the carbon frame and forks. Bottom line I think is that a 100 psi setup tubless, or not wold be a major headache with an older steel / ali frame, but carbon has made these types of tires really useable!

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