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Used Stans for years with no issues. Setting up Arch EX rims, yellow tape and new stans valve.
Tyre goes up but valve leaks air.
Faffed all afternoon - new tape, multiple valves - still have the problem. Got it inflated to 30, rode around the garden Ok then it spat all the air out again.
Seems positional, and also going over 30 seems to set it off.
I have ordered some Mavic valves as they have little rubber grommets.
Anybody else had this issue?
If you mean the rubber grommets on the outside, that's not the fix- there should never be any air pressure there anyway. The superstar/WTB valves are the best ime, they have a big conical base so they seal really easily.
Air bleeding out past the valve often means you've got a leak somewhere else- if the rim's pressurised then the valve hole is the easiest exit. Is it a new rim?
I'm struggling with some new Hope 20Five rims... bit like you, I've set up plenty of tubeless wheels over the years but it sounds like a similar thing. The tyre bead even locates but there's air getting out around the valve hole. I've tried different valves, retaped them, even got a seal with sealant and a ghetto grommet patch to sit between the valve and the tape but that ended in it losing all the air mid-ride... Seriously frustrating!
Air escaping from the valve hole is normally not from the valve hole, it's just an easy exit. On a stans rim check you have the little holes near the weld properly taped.
Thanks for the replies
Yes it is a newish rim - had a tube in previously - on my wife's bike and she rarely rides.
It is through the valve hole in the rim. The Stans valve has a substantial conical rubber seal but there seems to be a bit of play/ wiggle to it even with the screw tightened ++.
Cant see where else it would be from but I take your point.
I have a Mavic valve and it has a different rubber contact patch - long and rounded- I can't tighten it on a Stans rim without a rubber grommet (and I've lost them). Will try SS.
GTTH - yes exactly that problem.
Air escaping from the valve hole is normally not from the valve hole, it's just an easy exit. On a stans rim check you have the little holes near the weld properly taped.
Thanks - I retaped the rim today but will check once more esp at the weld.
I'd used some unbranded valves quite happily in the wheels that came with the bike and swapped them into the new Hope wheels along with somne new Stans tape. Thinking it was the valves that were the problem, I put 'proper' Stans valves in and retaped again with more new Stans tape - having read loads of stuff online and watched and re-watched their videos.
One thing I did pick up, djflexure, was that the valves shouldn't be overtightened but I wonder if you're right that the profile of the rim bed and the valve base shape isn't marrying up right?
benpinnick - I'd read the same as you've suggested and it makes total sense - if the air can get under the tape, it'll escape through the valve hole.
[quote=benpinnick ]Air escaping from the valve hole is normally not from the valve hole, it's just an easy exit. On a stans rim check you have the little holes near the weld properly taped.Also - make sure you've a lot of tape overlap. Stans Tape is great at sticking to metal rims, not so good at sticking to itself.
Only a few cm overlap - could be the issue. Would make sense that the issue starts when I go over 30. Perhaps its lifting the tape end?
Agree with the above - every time i've had a tubeless valve leak it's been from a leak elsewhere on the rim bed allowing air to escape into the rim cavity and then out through the valve hole.
Whenever I replace rim tape I always fit the tyre with a tube and leave at 40psi overnight. Seems to ensure all the tape really adheres to the rim. Cleaning the rim beforehand with isopropyl alcohol is a good idea.
I also dip the valve in stans before fitting, and nip up the collar with pliers (not too tight though). If you need a rubber grommet on the outside of the rim then you've lost already
Had the same in my hunt rims - there was a small nick in the tape and the sealant wasn't quite right (too gloopy)
If new tape isn't doing it then there may be a problem with the rim bed but it definitely manifested itself through the valve once it went above 40psi
PTFE tape wrapped around the base of the valve stem worked for me! This was on an old valve that I'd cut from an inner tube and trimmed down.
To update - it was down to inadequate overlap and lifting of the Stans tape. Fixed now thanks.
I've learnt something new - valve leaks are not in general a valve problem.
I thought it might be that. The trick of pre-seating the tyres with a tube also helps that bit of tape overlap stick to itself. It can be difficult to get the overlapping bit into the rim well otherwise.