Identify the Cannondale?
 

This is an SR, right? Seller says it's an ST...http://bikeforums.net/attachment.php...hmentid=467226

you can start with deciphering the serial number, thats the start of narrowing down what you own.

Vintage Cannondale website has a good guide for finiding it and deciphering

check it out here:

Vintage Cannondale - Information and Help

Double crank, you're probably correct, an SR.

I've asked for close ups of the drop outs (rear and fork) to look for the double mount locations. That seems to be the best confirmation to me...

I think an ST would have rack mounts on the seat stays. I can't tell from the pic.

My guess from the one pic is an SR by looking at the seat tube/tire clearance. The ST has the wider gap; longer wheelbase. Just a guess.

Looks like my SR.

Geometry's too tight for an ST, definitely an SR. Looks like an 87 or 88.