Because the stem on the tubualrs are too short and once the valve extensions are on, I am not able to tighten the valve so that air doesn’t leak out. How can I fix this problem with my tires continuing going flat?
If you can remove the valve core, you need the extenders that place this at the end of the extension so you can tighten it.
A customer of ours had that problem… starting a race with 180psi and ending with 80. We eventually fixed it by attempting to put the valve extender on several times… like 20-30 times, each time waiting for 4+ hours to see how much had leaked. It’s a matter of luck.
How fast are they going flat? Do they go flat while riding or even when standing still? My Vittoria’s will go flat in a couple of days just sitting there. No valve problem, just latex tubes that don’t hold air very well. Of course, if they are going flat while riding and fine when just sitting there, then it is probably a valve issue.
use teflon tape aka “plumber’s tape”
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Some tubulars will lose air overnight because they use a latex tube. (Enough that you’d have to add air before every ride.)
If you suspect an issue with the valve stem, I’d also suggest trying the Vittoria valve extenders. They are installed by removing your valve core, adding the extender, and then installing your valve core into the end of the extender.
I bought a set of 2002 Zipp 404 tubulars on ebay and had the same issue. I had my LBS take the tires off, tighten the valve extender, and reglue the tires.
Can you believe they only charged me $10.30 for all that?
You want these valve extenders: http://www.tri-sports.com/devaex.html
I usually do a little teflon tape on both ends for a good seal (not too much though, I cracked an extender once that way).
And as has been stated- if they are latex tubes expect pressure loss- over days though, not a few hours.
Chris