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Sorry for the "roadie" post, but it's not for me. Honestly.
Have treated Mrs Stoner to a set of chinese carbon 50mm wheels. They look the business. Some nice new Conti tyres too. But I decided to buy some valve stem extenders rather than new inner tubes with longer stems (since I have a box of 40mm stem inners)
BUT.... how do you use them?
Is it just a matter of opening the presta valve and screwing the stem extender on? That's what I have done, and it's not ideal at all. Since the extender is not air-tight on the stem, the pump doesnt give a pressure reading (it bounces up to 100psi+ and then drops as air in the pump hose leaks out of the extender/stem threaded joint).
and of course the valve itself is left unscrewed while the extender is attached.
Ive just gone back to the wheels this morning to check them, one has held air, the other hasnt. Before I conclude Ive bolloxed up the inner installation, have I done something stupid with the extender?
I got these ones:
http://www.wiggle.co.uk/lifeline-valve-extensions-for-non-removable-vc-2pk-40mm/
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I think the idea is to open the valve and screw the adapter on, then pump up, then remove the adapter and screw the valve in again. That's what I've done with such things. A right faff/
Alternatively, you could have bought your wife some normal, easy to use, lighter and more comfortable wheels with sensible depth rims. 😉
pffft - Ive been putting her off these for two years saying she has to get faster on her TT on her own first before splashing out on skill compensators 😉
The presta valve is inside the rim. I wouldnt be able to reach the valve and screw it back in having removed the extender.
I have a similar issue with my tubs using the same type of extender, I unscrewed the valve a smaller amount to give some back pressue, but theyre still tricky to pump up. second attempt I unscrwed the valve more and this helped being able to pump them up, I haven't found they deflate
from my experience its not possible to remove the extender and screw up the valve
Is there an o ring seal on the extender?
They came with a little o-ring each. no idea where they go though. I tried one on the end of the valve stem but when tightening the extender down it seemed to just squoosh out from the joint.
The other I didnt.
The one I fitted it to is the one that has flattened.
The O-ring should go in the bottom of the valve extender in order to seal it and prevent the problem you're seeing with air escaping whilst pumping it. The other thing you can do is put PTFE tape on the threads of the inner tube valve.
Leaving the valve permanently unscrewed shouldn't be a problem. In fact, before you put the extender on, you should firmly unscrew the the nut to the end of its threads so that you don't accidentally do it up again whilst putting the extender on.
cheers pdw, I will have another go.
I have some ptfe in the plumbing box too if I need it. [s]I guess the o-ring doesnt want to be sat right down the end of the valve stem threads where it can squoosh out, but better near the top so that it sits in the extender yes?[/s]
strike that. It seems it can only go down at the bottom of the stem threads. But every time I do that it squooshes out when I tighten the extender down. Pic coming.
What you want is one which can open and close the valve with the extender still on, such as [url= http://www.chainreactioncycles.com/in/en/topeak-presta-valve-extender/rp-prod7356 ]this[/url]
[img] 
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That way you know that the valve is properly shut after inflation.
Another issue is that if you have a puncture and want to replace the tube, you can rapidly deflate the inner without reverting to poking an old spoke etc down the extender tube.
Cheers, Rich
Get some tubes with removable presta cores, and the appropriate extenders.
Remove core from tube, and put it in extender - much better way of doing it.
Oh, one more point - try not to drop the valve extender inside the rim. It's a most frustrating job trying to rattle/coax it back out using a multitude of spokes/allen keys.
I have done this more than once 😳
Cheers, Rich
bollox to all this. I think I'll just buy some long stem inners 👿
Pics.
O-ring on stem:
[img] 
[/img]
O-ring squooshed out when extender tightened down.
[img] 
[/img]
I though valve extenders were only supposed to be used with valves with removable cores. So unscrew removable core, screw valve extender onto valve stem, with a bit of PTFE tape, screw core into top of extender, again with a bit of ptfe tape.
......or save yourself the hassle and go get a new box of long valve stemmed inner tubes - job done. One can never be packing enough rubber.
import - Member
Get some tubes with removable presta cores, and the appropriate extenders.
Remove core from tube, and put it in extender - much better way of doing it.
^^ this, can even be bought from Halfrods..
Dead easy to fit, take out the core, screw in the extended core & pump up. They too have a small O ring to seal them, I usually use vasaline to rub around the core first..
box of 10 Conti Race tubes off Ribble for £28.
Get some tubes with removable presta cores, and the appropriate extenders.
Remove core from tube, and put it in extender - much better way of doing it.
Sometimes. I bought the Continental valve extenders and they wouldn't screw onto Continental valve stems after I moved the valves!
I also bought some Profile valve extenders, with O ring. These screw directly onto the stem as per your photos and work just fine. I prefer these to the ones where the valve is removed. There is no thread on the ends for the pump chuck either.
stoner - you need to put the O-ring into the base of the extender, not on the valve. Very fiddly to do, but once done you should find the valve extender works just fine.
The only other thing to watch out for is when you put your pump on, make sure that the weight of the head doesn't unscrew it slightly as you're pumping.
cheers pdw.
just tried that....and shredded the o-ring.
I shall go with some ptfe on the stem thread and have another go.
I've got a pair of valve extenders in the shed. Will go check them out.
Yours if they'll work better than what you have.
Tim
They look just like yours.
Sorry.
Tim
[s]Your valve extenders aren't working because they're upside-down. If you want something to just stick on the end of your current tubes, you need extenders like turboferret posted. However - they're shit, don't bother :D[/s]
EDIT: Ignore me, I'm confused. njee is right 😳
Your valve extenders aren't working because they're upside-down. If you want something to just stick on the end of your current tubes, you need extenders like turboferret posted. However - they're shit, don't bother
No they're not, the OPs are being used as they were intended, seems they're just crap. The Conti ones are as you describe.
I used Conti ones on some tubs and they were fine, with tubes I'd just get longer valve ones.
Sam, thanks, but as I linked to in my OP, these are for non removable valve core inners.
Whoops! Edited so as not to confuse future generations 😀
I never managed to get the "don't remove the core" extenders to work - I tried Zipp (same sort of thing as the LifeLine) and Topeak (with the long internal sleeve to open/close the valve) and neither really worked satisfactorily. Of the two, the Topeak ones worked [i]slightly[/i] better as you can at least open and close the valve core, rather than having to leave it open the whole time.
After a couple of months I just bought tubes with removable cores. So far they've been far more reliable and easier to work with.
cheers all.
PTFE has worked, and it turns out there was a hole in the inner. Odd for a brand new one, and it didnt look like an installation pinch either (and I didnt use any levers).
Both up at 100psi, and I reckon will be fine.
thanks again