Tubeless valve - do...
 

Tubeless valve - do they just stop working?

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My bike has been tubeless since I bought it 18months ago with Peatys valves .

 

The front is fine but the rear now leaks air unless the valve is very tight. When you pump it up it also doesn’t accept pressure very well and the valve sticks.

 

Ive taken it apart, cleaned it in warm water and can see no sealent on it. Put it back in but with one ride was sticking again. 

Any advice ? Ta


 
Posted : 04/03/2026 8:58 am
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Posted by: FunkyDunc

The front is fine but the rear now leaks air unless the valve is very tight. When you pump it up it also doesn’t accept pressure very well and the valve sticks.

 

The needing to tighten the valve might mean the hole in the rim tape is compromised? Maybe need to re-tape?  I find a valve that sticks or is resistant to air pressure when pumping is usually blocked with sealant.  Especially if you leave it with the valve at 6 O'clock for any length of time. Quickly fixed by removing the valve core and carefully poking through with a cocktail stick. If the core itself is gummed up, replace it. Valve cores are cheap as chips.


 
Posted : 04/03/2026 9:12 am
 PJay
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Mine seem to go every so often, often the shaft that the nut sits on gets a bit bent & inside they can clog up with sealant. Packs of presta cores are available for pennies online so there's no point stressing over them, I just change them when they start playing up.


 
Posted : 04/03/2026 9:14 am
Keando reacted
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Last time i was in my LBS i asked about valve cores and they just asked how many i wanted and gave them to me


 
Posted : 04/03/2026 9:24 am
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I've had a few valve cores gunk up to the point where you couldn't use them. Just replaced them... The ones I've had problems with were Peatys valves. Never had an issue with Stans ones.


 
Posted : 04/03/2026 11:47 am
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Posted by: FunkyDunc

The front is fine but the rear now leaks air unless the valve is very tight. When you pump it up it also doesn’t accept pressure very well and the valve sticks.

and

Posted by: blokeuptheroad

If the core itself is gummed up, replace it. Valve cores are cheap as chips.

when I first got tubeless, I bought new valve assembly about once a year... until I realised that its just the cores that are the problem. 

They are about a pound each from a "brand"; or 100 for £18 on ebay, don't know if the cheaper ones would be noticably worse? or even different at all?


 
Posted : 04/03/2026 11:54 am
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One of the few muc-off products that seem to work well are the Big Bore Lite valves, they do away with the standard presta valve and don't clog


 
Posted : 04/03/2026 1:17 pm
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Change the core and it'll probably be back to normal. Occasionally they need a proper clean of the inside of the shaft using tools. Not worth cleaning cores.


 
Posted : 04/03/2026 1:26 pm
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I feel that constantly binning valve cores is a bit wasteful, am going to try those new BBB core cap things which can be retrofitted to the top of the valve stem.


 
Posted : 04/03/2026 1:34 pm
 mert
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I use a knackered old 4mm drill bit to clean out the inside of the valve stem. And usually just replace the cores. But 20 minutes in *very* hot water gets the gunk out of the core if you're stuck.


 
Posted : 04/03/2026 1:38 pm
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I've just got some of those Santa Cruz Fillmore valves. Running tubeless on two bikes, including an insert on the back of the hardtail, I'm driven mad by standard Presta valve cores clogging, and I've also had issues with the bit on the inside that deals with the insert blocking. One pair installed, radical improvement in airflow vs a completely clear Presta valve (the gauge on the pump doesn't leap half as much when pumping), and the design looks like it should work well. Not cheap but hopefully worth it in hours saved trying to pump up tyres through clogged valves!


 
Posted : 05/03/2026 1:31 pm
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Worth wiping the core with GT85 every so often, keeps them gunk free. 


 
Posted : 05/03/2026 2:53 pm
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I got given some Filmore valves a few years back. Thought they were great. 

Then last summer I screwed the valve cap back on and the entire threaded section of the valve stem just unwound in a spiral - it had corroded away from the inside and the torque of me putting the cap on was enough to shear it off. I think they lasted 3 years +/-  

Sticking with boring old presta valves and have a bag of eBay cores to change out every once in a while. 


 
Posted : 05/03/2026 3:23 pm
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Never had an issue with generic cores. I take them out to top up with sealant though.


 
Posted : 06/03/2026 9:52 am
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Thanks all I was being a bit stupid really thinking there would be something unique about Peatys. 

The wife’s bike came with some spare tubeless valves so will just take a core from one of them !


 
Posted : 06/03/2026 10:43 am
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"Then last summer I screwed the valve cap back on and the entire threaded section of the valve stem just unwound in a spiral - it had corroded away from the inside and the torque of me putting the cap on was enough to shear it off. I think they lasted 3 years +/-  "

Oh, that is annoying! Which sealant were you using?

I had a Presta valve stem snap clean in half but I think it was over 6 years old and corrosion had weakened it - it just came off in the pump head.

If I end up back on Presta valves I'll try the GT85 trick!


 
Posted : 11/03/2026 11:03 am
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Posted by: iainc

Worth wiping the core with GT85 every so often, keeps them gunk free. 

This. A smear of silicone grease does a longer-lasting job

 


 
Posted : 11/03/2026 1:13 pm