Road Bike Racing - valve extenders

I am looking at getting a set of carbon tubulars with a 50mm rim for racing.

I have never tried tubulars before, but I understand that you need a valve extender to inflate ones with deep section rims.
How exactly does it work? Does it attach to the original valve on the tire?

Mine screw onto the original valve. :)

Be sure to use teflon plumber's tape to seal the extender and the valve threads, otherwise the leaky air situation can really make pumping up your now inaccessible tubular presta valves a massive pain in the ass. I have a set of tubulars glued to my Zipps that they came with; the original owner (I bought them used) never did this.

DO it. It hasn't been bad enough for me to strip off these tubulars, tape the valves and reglue them (that is an even more massive pain in the ass), but it has been close. Are the tubulars worth it?

Yes.

^^^^
+1 Teflon tape is your friend.

Matt - I am looking into getting a set of sew-up wheels (curiosity, mostly) and have a lead on a pair of Shimano/Campy Shamal sew-ups for $100. I don't think they are CF but at that price, what the heck. If you are interested, PM me and I will pass on the information.

And make sure the valve stem is wide open before you screw on the extender, then glue the tire on the rim.