Mavic Inner tubes

casatikid

Hi, I Have fitted Mavic inner tubes with smooth valves on one of my bikes and I'm having trouble getting upto 115 psi into the tube when using my Joe Blow sport track pump. I get to about 90 odd and then air starts to leak out.
I thought it was because the tubes that I normally use ( Vittoria) have threaded valves and they had worn the valve seals so I replaced them as they were worn but still having the same problem.
Anyone else having trouble with Mavic tubes.?

sungod

check the valve cores are tight in the stem, if they're like conti ones they are a bit loose when shipped

casatikid

sungod wrote:

check the valve cores are tight in the stem, if they're like conti ones they are a bit loose when shipped

Yahoo,
I will give it a try.Thanks.
I take it a pinch with a pair of pliers will be okay?

sungod

just screw them in tight, pliers or a core tool, either will be fine

svetty

You are correct: The rubber cores inside the heads on those pumps get worn over time as they are pushed onto and off of (threaded) valves. Eventually this means that at higher pressures they fail to seal properly - especially on smooth valve stems - allowing air to leak past them at higher pressures.

I too tried to resolve this with new 'contents' for the head units but they don't work especially well as you can't replace everything inside them.

Sigma Sport sell new entire head units for £10 a time which is the easiest way to resolve this one

sloppyschleckonds

115 psi on a clincher?

I'm Out.

drlodge

SloppySchleckonds wrote:

115 psi on a clincher?

I'm Out.

115psi for a 23c rear isn't massive. Although now with tubeless 23c I'm running 80/90