Ian Szekeres wrote:

I really would like to use a quill stem on my newly purchased bike,
unfortunately it uses a threadless headset system.
-snip-
There's a company that sells 1" threadless headsets (G-Force) that
attach entirely externally, allowing you to keep your threadless fork and
install a conventional stem.
and this off Sheldon's site:
The YST "GeForce" headset has a collar which slips over the steerer, and is
clamped to it with a binder bolt near the top of the collar. The outside of
this collar is threaded, and the upper bearing race screws onto these
threads. The upper race assembly is fitted with a binder bolt that clamps it
tight onto these threads when the desired adjustment has been attained.
-snip-

Yes, that's what you want. It's the discontinued YST
"G-Force". They certainly came in handy, though:
http://www.yellowjersey.org/photosfr...st/FISHBAR.JPG

You might fabricate something to do that.
--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971