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Old 02-27-08, 04:49 PM   #1
king-tony
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Valve extenders

What is the advantage of running a valve extender vs. a long stem valve on a deep rim wheel?
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Old 02-27-08, 04:52 PM   #2
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What is the advantage of running a valve extender vs. a long stem valve on a deep rim wheel?
I have both but have never used the extenders.
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Old 02-27-08, 05:02 PM   #3
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If all you can find is a short-stemmed tube, you can still fill it.
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Old 02-27-08, 05:04 PM   #4
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What is the advantage of running a valve extender vs. a long stem valve on a deep rim wheel?
The only advantages to the valve extender that I am aware of are that: 1) It is sometimes hard to find the long stem tubes (some shops don't carry them). 2.) I have multiple bikes but only one with deep rims. I just buy the short stem tubes and use an extender to make them interchangable.
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Old 02-27-08, 05:09 PM   #5
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After you pump up the tire, you can take the extender off, tape over the hole and be even more aero
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Old 02-27-08, 05:51 PM   #6
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- better to have a valve extender and use it than to need a valve extender and not have one...
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Old 02-28-08, 05:53 AM   #7
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When you get your SECOND flat on a ride and have to borrow someone else's short-stem tube......

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Old 02-28-08, 09:13 AM   #8
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Valve extenders are nice. There are two types - the "tube" type which simply extend the reach of the pump but do nothing functionally for the valve, and the other type which is the kind which replaces the top part of the valve with a longer valve, typically on tubulars.

The first type (I'll call it Type 1) which is more common leaves the valve unscrewed. You unscrew the presta tip, screw on the extension, pump up. The extender is simply a threaded tube, one end wider for the valve, the other end narrower for the pump. This leaves you vulnerable to a sudden impact-related deflation - if you hit a bump pretty hard at the right place on the rim, the valve depresses and deflates just a bit. Suddenly you have a slightly under pressure tire that mysteriously doesn't lose any more pressure and has no punctures when you check after the ride/race. That is a disadvantage. Well, for me it was an advantage because it happened to the other guy in the break and he lost.

The second type (Type 2) really is a valve extension. You unscrew the original valve core and replace it with a longer one. Or you unscrew the valve core, screw in an extension tube, and then screw the valve core into the new extension tube. You have a presta screw tip thing at the top, you pump up the tire like normal, you screw the presta tip thing shut like normal. Only thing is that it sticks out of the rim.

I have tubes which have mid length valves, I think 48 mm, in a DV46 rim. Needs an extender (I have a tube type extender, Type 1, an original Zipp one, taped to my frame). Just enough of the valve sticks out that it's easy for me to screw the presta tip shut.

I have tubulars with the Type 2 extensions. I put them on last time I glued tires simply because I had them. They stick out a little too much so I'll stick with the procedure I describe below from now on.

With Type 1 extensions, you can also use a small allen wrench or something to screw the presta tip shut, even if the tip is inside the rim. I'd do this before races or group rides or solo rides with no pumps.

Finally Spinergy had a Type 1 extension that had a thin metal tube inside - it would grasp the presta tip and you could tighten the presta tip with the extension on the valve and then remove the extension altogether. I like these a lot but I've misplaced them all in the past 10 years or so.

cdr
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Old 02-28-08, 09:37 AM   #9
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Originally Posted by carpediemracing View Post
Valve extenders are nice. There are two types - the "tube" type which simply extend the reach of the pump but do nothing functionally for the valve, and the other type which is the kind which replaces the top part of the valve with a longer valve, typically on tubulars.
The first type (I'll call it Type 1) which is more common leaves the valve unscrewed. You unscrew the presta tip, screw on the extension, pump up. The extender is simply a threaded tube, one end wider for the valve, the other end narrower for the pump. This leaves you vulnerable to a sudden impact-related deflation - if you hit a bump pretty hard at the right place on the rim, the valve depresses and deflates just a bit. Suddenly you have a slightly under pressure tire that mysteriously doesn't lose any more pressure and has no punctures when you check after the ride/race. That is a disadvantage. Well, for me it was an advantage because it happened to the other guy in the break and he lost.
The second type (Type 2) really is a valve extension. You unscrew the original valve core and replace it with a longer one. Or you unscrew the valve core, screw in an extension tube, and then screw the valve core into the new extension tube. You have a presta screw tip thing at the top, you pump up the tire like normal, you screw the presta tip thing shut like normal. Only thing is that it sticks out of the rim.....
cdr
Type 1 extenders do not seal very well. Zipp recommends using teflon tape on the stem threads for a better seal. If you don't use teflon then you have to pump quickly to ensure that more air gets in than escapes in the process.

Type 2 extenders work best, BUT they only work with tubes that have stems with removable cores. Not all tubes have cores that are removable.

Bob
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Old 02-28-08, 10:32 AM   #10
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The extenders I got with my carbones come with little rubber o-rings. I have problems finding 81mm stem tubes and the 61mm stems are just too short for my pump. I prefer to use the 81mm tubes though but I always carry the extender just in case, I can always transfer the o-ring off the flatted tube to the new one. These would be type-1 extenders as mentioned above. I never leave them on just keep one in my pack and use it to fill the tire then remove it and tighten the valve. If I had to use a tube <61mm then I would have to leave it on but so far no need.
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Old 02-28-08, 08:54 PM   #11
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Thanks for the responses. I bought a couple of 80mm tubes today and will keep the valve extender in my flat kit to be safe.
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