I have a Topeak PrepStand Pro repair stand that I am currently using for my Allez road bike. I am clamping the bike by the seat post unless I am just "sitting" the bike of the stand by using the top tube. However i do not clamp it. I do not even apply presure to the tube.
Now looking at the TT bike, their seat post are rather rectangular and flat. What is the proper way to clamp it to a stand without causing any damage to the bike and without any fear of the bike falling as you run through the gears (as in when cleaning the chair or so).