Hi, I was trying to find the head tube measurement of a frame I want to get and saw this thread. Sheldon Brown has a quick trick to figure this out on threaded head tubes without taking anything apart or pulling out a ruler:

Put a quarter up to the quill; if it's diameter is a little larger than the quill it's 1", and if the quarter is a little smaller it's 1 1/8".

http://www.sheldonbrown.com/headsets.html

Sorry to keep posting in an old thread, but it may help people searching for an answer to the original question.

-g