Oh and a note on sizing,
Chuckk is right, Cannondale's officially listed sizing (at least for their 80's and 90's stuff) is measured from the center of the bottom bracket to the top of the top tube as measured along the length of the seat tube. I've got my ST600 with me at work right now and I double checked the measurement and it's a spot on match to the listed size of 25 inches.