I’ve been using tubeless for a while and never had any real problems until now.

I’ve just changed to a set of Stans Crest.I’ve taped the rims and used the superstar valves from my old rims.They tyres went up without problem but can’t stop the valve stem from leaking.

I’ve tried them loose,tight ,one layer of rim tape,several layers around the valve hole but they still leak.

Do I need to buy a new set of valves or am I missing something?

cheers

Have you added sealant yet? That should seal any leaks around the valve..

Yes,but the tyre is flat before the sealant stops the leak

Generally I find if there is a problem with the tape not sealing the rim bed, the air always seems to find it’s way out round the valve hole. It’s very rare in my experience the issue is the valve.

If it is, a bit of vulcanising glue around it before you put it in stops it.

As Hob Nob says – everytime I have had it leaking at the stem it has been the tape at fault

+1 leaky tape

I’ll re-tape them and see how I get on. I did managed to get them up OK yesterday and rode 20 miles on them today but by the time I’d driven home the front one was flat and I can’t seem to stop the leak.

When you re-tape them , add an inner tube , pump up as hard as you dare & leave for 24hrs , then remove , this’ll make sure the tapes stuck good & proper.

Then remove the tube , put in your tubeless valves & sealant , pump your tyre up how ever you normally would for tubeless.

I had this recently, tape was fine. In the end I wrapped a bit of electrical tape around the valve stem where it nearly contacts with the rim, held air tight ever since.

It’s probably not the valve itself leaking.
More likely it’s one of the spoke holes inside the rim leaking in to the hollow rim.
The nipples will form a good seal with the outside of the rim, leaving the valve hole as the only place for the air to escape.
You could prove this by loosening one spoke and seeing if the air then escapes from that spoke hole.

mtqgraham is spot on, I’ve chased a “valve leak” in the past and discovered it was a spoke hole leak.

Right , off the garage to re-tape the rim and see if that sorts it

If it turns out not to be the rim tape, try some LSX (Plumbing sealant) around the valve hole. Took my rim from so leaky you couldn’t even inflate it, to totally sealed for months.

Good shout about the plumbing stuff.

De-greased the rim and re-taped,put a smear of none setting mastic around the valve hole and up she went without any leaks 🙂

cheers chaps