Philip W. Moore, Jr. wrote:
Howdy folks. I've got a pair of Spinergy Rev-X tubular wheels that
require a valve extender for my Tufo tires. As those who use valve
extenders know, you have to leave the valve open before you attach
the extender to the valve. But for me, this results in a loss of
pressure in the rear tire. Have any of you ever dealt with this? If
so, how did/do you solve this problem.

As others said, it must be that particular tire/valve. (The front uses an
extender, too? And it doesn't leak?)

Could you use the extender to pump up to full pressure -- then remove it and
close the valve -- and then replace the extender on the /closed/ valve?
You'd just have to re-assemble the arrangement to add air...

Clincher Bill