Faulty valve

I fitted a new Foss tube into my 36er on Sunday. Today I took it out for a ride only to find the tyre was almost flat. I knew it wasn’t a puncture so I tested the valve to see if it was faulty.

I poured some water into the valve and sure enough a bubble developed showing that air was escaping. It’s annoying because the Foss tube I replaced, also had a faulty valve. :angry:

I’m thinking of replacing the Foss 36" tube with a 28" X 2.35" tube. Will this work out ok? Is it likely to blow out? :thinking:


I ran a 29er tube in my 36 exclusively, and never had a blowout.

Thanks, jtrops. The 29" tube should be available in my local bike shop. :slight_smile:

I wonder has anyone else had this problem or maybe my pump is damaging the valve needle in the tube.

I’m inclined to think that it’s more likely that the Foss valve doesn’t cope too well with pressure higher than 40 psi.

If it’s a standard sized Shraeder valve, see if you can just put a different one in. Or start with the old trick of taking the valve out, cleaning it, covering it with saliva and putting it back in. Sometimes it’s just a poor seal around the valve.

Thanks John, I’ll try that.

There’s no obvious damage so it’s probably just a loose seal as you suggested.