Well, I'll try. The 'zipp' brand extenders (the simplest kind--there are others out there that work differently) are basically just hollow tubes that lengthen the valves so you can access them with the pump head.

Installing the extenders correctly requires 2 steps: 1. the presta valve must be opened and 'forced' open (unscrewed) just a hair beyond where the end of the threads typically prevent the valve head from unscrewing off completely (this step opens the valve so air can come in and the slight 'forcing' causes the valve head to lock into position so time and vibration doesn't cause the valve head to screw itself closed as you ride). 2. then the zipp extender must be screwed on fairly tightly onto the valve stem with a few layers of teflon plumbers tape (this step gets the extender on and the tape seals the connection between the two).

When you pump up the wheels, you do it as you do normally with these exceptions: you don't need to open (unscrew) the presta valve when you start and you don't close the valve when you are done (actually you can't open or close it, as it is out of sight under the extender). The wheel should maintain its pressure (if the valve is not defective, that is).

My guess is that your friend that had pumping problems has not done some or any of these steps, has some problem with his pump, or possibly has a tube with a bad valve. If you take a regular floor pump that works on a standard presta valve (and shows the correct pressure) and use it on a presta valve with a zipp valve extender (that has been corrrectly installed--as above) then the pump will work normally and show the right pressure as you pump.

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Where would you want to swim ?

Make sure you are using a small strip of plumber's tape around the threads of the Presta valve before you screw on the extender. Additionally, the new Zipp extenders have a 3mm allen key broached into the nose for easy tightening. If you don't use the tape the air will still enter the tube, however it will leak out between the extender and your pump, which will render your gauge useless. Feel free to contact me if you need Zipp extenders or other tips. info@wheelbuilder.com

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Wheelbuilder.com

I could never get accurate tire pressure readings with the regular valve extenders. I have recently switched to extenders that allow the valve core to be installed at the top. You remove the valve core from your tube, attach the valve extender in the normal way, and then install the core in to the top of extender... Maybe easier to do then explain. Once it's done the gauge reads just like normal. Of course you still eed the Teflon tape and the extender must be on tight.



A quick search found these: http://www.trisports.com/devaex.html

Would you recommend installing 2 ZIPP extenders for both tires (with teflon tape) and leaving the extenders on even when riding ?

So do you recommend bringing 80mm stemmed tubes for races to avoid all the extender stuff if one flats in the middle of a race?

I leave the extenders on and I carry tubes with the plumbers tape and extenders on, so if I get a flat during a race I'm all ready to go! The long stem tubes don't work, they're not long enough!!!

even the 80mm ones? I just bought three but I haven't tried them out yet.

correct, even the 80's. There's not enough valve coming through to get a pump or CO2 thingy on there!!

80mm tubes are perfect for Zipp wheels, but there are two issues to consider when using them them. First, 80mm tubes are pretty rare, so if you don't have a spare you will need to borrow an extender from someone or carry an extender. Second, the price of an 80mm tube is significantly higher than purchasing valve extenders seperately. If money is not an issue, I highly recommend the 80mm veredstein seamless tube, but make sure to stock spares.

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Wheelbuilder.com

I know of two tubes...long stem and short stem, not sure of the mm's! :-/ But is there a third tube with an even longer stem?? I always use the long stem for my training wheels as they're deep rims. However, the long stems I'm using don't work for my 404's?!?

There are several lengths available in the following range. 36mm (short), 48mm (medium), 60mm (long), 80mm (extra long). Veredstein makes a very nice 80mm, but they run around $8 per tube. E-mail me if you need tubes or extenders info@wheelbuilder.com

Richard

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Wheelbuilder.com

cool, thanks for the info! I'm most familiar with the 48's and 60's!! :-D So the 80's probably do work!!

The 80s work but I need someone to hold the pump head on the valve while I pump or it slips off. If no one is around, I screw on a valve extender (no teflon tape) but type that lets you open and close valve, pump it up, close valve and unscrew extender. It also comes in handy if the LBS is out of the 80s.

Yes, you leave them on while riding as installing the extenders is a semi-permanent installation; you would only take them off when the tube won't be used anymore or at least not for aero (i.e., very deep) wheels. I even get a 3rd valve extender and prep a third tube with the same process I described so I have a spare ready and available.

Also, one thing I didn't say in my original post is that to let air out of a wheel (or tube) with the extenders installed, you need a slender 'poker' (a very small allen key or a large paperclip unbent will do) which you insert into the extender to reach the original valve to release the air.

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