Ken Spencer wrote:
Can the top tube be used, if I am *careful* about clamping it, or would
that be fatal?

I've clamped my Waterford 1200 Reynolds 753 steel top tube in my Park
PS5 stand for about 7 years now. As long as you don't try to crush it
with the clamp, it won't harm anything. When using the top tube the
bike also sits on the stand very nicely without even closing the clamp.
Its fairly difficult to crush any tubes when the clamp isn't even
used.

I buy bike frames that are properly sized using the old time method of
a fistful of seatpost showing. I do not use the current method of
buying undersized frames and making them fit with 400 mm long
seatposts. Thus with my road bikes, there is not enough seatpost for
the Park clamp to grab. I think you will do far more damage by
unloosening the lugged in seatpost clamp/bolt on the frame every time
you want to work on the bike just to pull the seatpost up. And then
retightening it to put it back to the right spot. Assuming the right
spot is within a 1/4" or so of the spot it was.