Hi Tom-- just busy lurking. There were two aero posts of different dimensions,one the Tange aero tubing and the other ( which I have never seen and may never have actually been manufactured like 10 pitch derailleur group) was for other aero tubing, probably Columbus. But as I said, that comes from the AX literature. For all practical purposes only the Tange oval exists and I have a few. Alan Bernstein, crappy NY weather today.