Presta Valve Leaks?

Okay, I'm used to being a knowitall about bicycles, but this has me
stumped. The inner tubes in my Pashley 29er keep going flat with slow
leaks. I have removed the tubes and overinflated them to inspect for
punctures, and I have inspected the rim and tire. I have even done a
little underwater testing, NOTHING.

Is there something obvious about presta valves that I don't know? I'm
tightening the funny little screw thing after inflating.
This problem usually occurs after inflating to a fifty pound pressure.
carjug the perplexed


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carjug
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In my experience, Presta tubes are lighter and more porous. They tend to
loose are over time. Some brands are worse than others in this respect.
Maybe try a heavier, thicker tube, or ask the LBS what they recommend.



Cheers…. Mojoe


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carjug wrote:
*Okay, I'm used to being a knowitall about bicycles, but this has me
stumped. The inner tubes in my Pashley 29er keep going flat with slow
leaks. I have removed the tubes and overinflated them to inspect for
punctures, and I have inspected the rim and tire. I have even done a
little underwater testing, NOTHING.

Is there something obvious about presta valves that I don't know?
I'm tightening the funny little screw thing after inflating.
This problem usually occurs after inflating to a fifty pound
pressure. carjug the perplexed *
Tighten the little nut only hand-tight. But it sounds like you might
have a burr on the rim or something that punctures the tube at a certain
psi. Completely remove the tire and tube and check: the rim for sharp
parts, burrs, rough spots; the rim strip for proper placement; the
surface of the rim strip for spoke poke-through and the like. If you
are using a rubber rim strip replace it with a quality cloth one. If
you can't find anything, go over the entire rim surface with fine steel
wool. If you do find something, use emery cloth, then steel wool to
smooth it out. If all that doesn't work, consider using a heavier-duty
tube.

My two cents.


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U-Turn - Small fish, big pond

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I'd almost go for a new tube because they are pretty cheap.


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joona - )-O --Neat

Faster, Higher, Unicycler
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make sure you have an accuall 29er tube in there.a real 29er tube is
700x52 where as a basic 700c tube is only 700x38c or skinnier.

if you dont have a real 29er tube in there the walls of rubber will be
paper thin by the time its reaches the volume needed to fill a 2.1
tyre...


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forget_your_life - a.k.a. jagur

dream one dream many....

-jagur-
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