Valve hole cutting tube

rtnicho
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Valve hole cutting tube

Postby rtnicho » Sat Dec 23, 2017 10:52 am

Seasons greetings to all
I've got a set of Kysrium SLs and the valve hole keeps cutting the tube on the rear. So far I have tried:
Gently filing the inside of the hole to remove any burrs and sharp edges
Using different brands of tubes (in case it was a bad batch)
Changing the rim tape
Putting hole in a piece of old tube and putting it over the valve between the tube and the rim.
I've run out of ideas.
Any thoughts?
Cheers

eeksll
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Re: Valve hole cutting tube

Postby eeksll » Sat Dec 23, 2017 12:13 pm

can it be the rim tape causing the issue?

how "rough" are you at removing the pump head after pumping up the tyres?

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darkhorse75
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Re: Valve hole cutting tube

Postby darkhorse75 » Sat Dec 23, 2017 1:07 pm

Leave the knurled nut on the valve stem. Screw it down so it's at the base of the stem and install tube so the nut is on the inside of the rim.

rtnicho
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Re: Valve hole cutting tube

Postby rtnicho » Sat Dec 23, 2017 4:20 pm

could be the rim tape but the same thing happened with two different rim tapes
I could also be a bit rough but I've got about 10 sets of wheels on the go on various family racing bikes and don't have this problem with any other
I'll try the Knurled nut trick
Thanks to you both

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foo on patrol
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Re: Valve hole cutting tube

Postby foo on patrol » Sat Dec 23, 2017 7:22 pm

darkhorse75 wrote:Leave the knurled nut on the valve stem. Screw it down so it's at the base of the stem and install tube so the nut is on the inside of the rim.


Not all tubes come with this type of valve stem. :wink:

Foo
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BJL
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Re: Valve hole cutting tube

Postby BJL » Sat Dec 23, 2017 7:38 pm

darkhorse75 wrote:Leave the knurled nut on the valve stem. Screw it down so it's at the base of the stem and install tube so the nut is on the inside of the rim.


I did this by accident once. The next time I got puncture and failing to find any other fault, I attributed it to this. However, I couldn't confirm using the usual bucket of water test so made an assumption (yes I know) going by the rubbing marks on the tube around the valve where the nut was.

:?

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Duck!
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Re: Valve hole cutting tube

Postby Duck! » Sat Dec 23, 2017 8:06 pm

Ksyrium SLs (and Elites) are sealed rims, so the rim tape is redundant.

Make sure the tyres are properly inflated. If they're too soft the tyre will "creep" around the rim under drive and braking loads, pulling the tube with it, causing it to wear on the edge of the hole.
I had a thought, but it got run over as it crossed my mind.

rtnicho
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Re: Valve hole cutting tube

Postby rtnicho » Sun Dec 24, 2017 5:33 pm

Thanks Duck
After fitting I inflate the tyres to about 100 psi, so under inflation is not the issue. Also, they go flat without ever being ridden (overnight).

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rkelsen
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Re: Valve hole cutting tube

Postby rkelsen » Mon Dec 25, 2017 7:21 pm

How's your pump? I once had a track pump which would grip the valve too tightly. The amount of force needed to disengage the pump head from the valve would cause the valve to tear itself from the tube.

The issue went away when I started using a better pump.

rtnicho
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Location: Adelaide

Re: Valve hole cutting tube

Postby rtnicho » Tue Dec 26, 2017 5:22 pm

rkelsen wrote:How's your pump? I once had a track pump which would grip the valve too tightly. The amount of force needed to disengage the pump head from the valve would cause the valve to tear itself from the tube.

The issue went away when I started using a better pump.


It's also a possibility. I'm using 2 Topeak Jo Blow Sports. Strange thing is it's always the same wheel out of 20 odd I use the pumps on. I wonder if the wheel has a particularly thin area around the valve hole which, no matter what I've tried so far, still cuts the tube. I haven't had a chance to try the nut trick yet as I'm away.

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Nate
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Re: Valve hole cutting tube

Postby Nate » Tue Jan 02, 2018 10:58 am

You filed the hole? how?
that'd be really tricky IMHO & would leave a rough/coarse finish.

A file wont leave a nice surface, i'd suggest some sandpaper (fine wet & dry) using a drill bit or dowel & put the paper on the end of it. (like the ol fellas used to start a fire with sticks back in the day)
Then sand/polish it to a really smooth finish.

Youtube valve grinding - similar method to that.

rtnicho
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Re: Valve hole cutting tube

Postby rtnicho » Fri Jan 05, 2018 2:03 pm

Thanks Nate. Actually used an extremely fine (jeweler's??) round file which my father had, followed by a clean up with wet and dry.

By way of an update I gave it another bit of a file with W&D paper wrapped around a small pencil, did the knurled nut thing, put the valve though a hole in an old tube. About 100 kms later it's fine. I'll update if this hasn't solved it.

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