Earl Bollinger said:Quoted message said:This has happened twice on my already, kind of weird. For no
obvious cause, my rear tyre would flat totally. The first one was
two weeks ago just after leaving the front door (tyre checked).
Within 10m, it suddenly went flat and totally flat. Then this
morning, after resting against the wall overnight, it's again
totally flat. No puncture found again. In b/n time, the same
wheel/tyre/tube has been on quite a number of long rides without
problem.
Quoted message said:Quoted message said:Anyone seen similar? I am totally perplexed as to what the cause
may be.
Quoted message said:I have seen this problem happen a number of times with Presta
valves. Leave the little plastic dust cap off the valve. Don't
bother screwing the little lock nut back in either.
This all sounds so much like the knurled lock nut causing valve stem
separation from the tube, which is what this might be. There was a
manufacturing period where stem attachment was incorrectly done.
Masochists decided it was their own fault because they used the stem
jam nut.
As I pointed out, you can tighten the jam nut manually as tight as you
can before inflation to 100psi and note that the nut is loose after
inflation. That is how great the force of inflation is compared to
finger tightening the nut that is there for the purpose of using a
frame fit pump.
Quoted message said:If the valve gets a tiny bit of crud inside it may not seat all the
way, and when you put on the dust cap, it starts to leak. I quit
bothering with the tiny lock nut too, leave it out, I had the small
threaded valve shaft break off.
Stems break because the pump force was aimed at the stem instead of
the fist of the hand holding the pump on the valve stem. Don't hold
the tire, hold the pump head.
Quoted message said:I also have had the little nut screw off the end without turning the
threaded shaft thus opening the valve. Now you are stuck as you
can't put air in.
Quoted message said:Is the valve end bent? Sometimes this causes the valve to leak too.
Of course like others mentioned tubes do go bad.
How so?
Quoted message said:I had one tube that would leak out after ten hours or so. I had to
inflate the tube like a balloon to find the super slow leak. I was
a lot of luck as even pumped up like a balloon I almost missed the
slow leak. But as luck would have it the tiny hole was on a seam,
and I was unable to get it to patch good.
Use a BIC shaver head (break off the handle so it will fit in the
patch kit) and shave off the raised seam. You can't get rid of the
seam with sand paper.
Jobst Brandt
