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First tyre, no problems. Second tyre, impossible.
As soon as it reaches 20 psi, air stars to come out between the valve and the rim, something that should not happen at all. Tried different valve, grease, lots of sealant and shaking. It does not do the job. Once the tyre deflates, if i press it down you can see the sealant coming off from the same place
There is nothing (at the naked eye) wrong with the rim so what that heck is going on?? Any similar experiences?
What are you using? Sounds like UST with bolt-on valve, as opposed to rim-strip or BMX tube methods.
al.
Yes. Had this very problem (also on second tyre!) last week setting an ACX on Stan's Flow rim. Air blasting out under the valve.
I eventually - after about an hour - got it inflated OK (and it's stayed up since) by doing the following:
1. Really swearing hard at it;
2. Nipping up the little valve collar thing fairly tight using long-nosed pliers. No idea if that is what did the trick but it stayed up as soon as I'd done that. It may have been the swearing and threatening to kick it round the house though.
Good luck!
I foudn I got this because air was getting inside the rim and couldn;t get out past the spokes as easily as it could the valve.
I now go round a couple of times with electrical tape to make sure that the spoke holes are sealed properly.
I've been trying to help out on this one. I've got 8 UST rims that I've never had a problem with & 2 Stans rims that have been fine. I've not had any tubeless problems using UST tyres or normal tyres.
But this one is fubarred - Stans 355 Hope Hoop with tape & Stans valve, wheel from Roger at Wheelpro. Last night a new valve came, and exactly the same problem. Air leaks out at the valve, and the valve lockring is tight enough (I wouldn't want to do it any tighter). Same with different tyres too. Rim looks fine to the eye.
I can vouch that the swearing really hard solution has been tried to the max.
Suspect it needs to go back to Roger / Hope.
The stans rims have the locking rim and once the sidewalls go ping no leaks 🙂 I had this trouble and later found out that my major valve leaks was due to a ripped valve seat - One new rim strip later and sorted - worth checking before you get too angry 😉
Maybe redo the yellow tape? Stans say you're supposed to key the rim with fine sandpaper, degrease it and then do the tape really ****ing tight.
I probably should have done, but I'd been through all the steps he said. Had to redo the tape in any case once as I managed to rip it.
just add a rubber washer/seal to the top of the valve - the mavic valves come with them
One "logical" thing that can be happening is if the air is somehow infiltrating between the yellow tape and the rim, and therefore can only escape via the valve hole. This would kind of explain what is happening and why cannot be sealed (latex is not getting there because the hole is very small). As mentioned before, this only happens when the pressure goes above 20 PSI, which suggests some internal pressure is needed to expel the air via that hole.
All very strange. Agreed to check the rim and yellow tape tonight again and post back to Roger after…
Got any electrical insulating tape? As a test, run that over the top of the yellow tape. If it stops it then the leak isn't at the valve but in the yellow tape somewhere else.
If that's it, then one of two solutions: More yellow tape or kill the cat that pierced the tape.