is this bike any good? someone local is selling theirs.
IMnsHO, not as good as the later CAAD3 and up frames. I’m trying to remember off the top of my head if the 2.8 has the long drop outs. There were some other “improvements” the CAAD series had over the 2.8, but they don’t come to mind at the moment. Oh wait–you might want to check the dropout spacing as well. It may not be compatable with today’s hubs/cassette spacing.
HTH
Brett
The 2.8s had the “long” dropouts, which were essentially a centelevered design that was intended to stiffen the rear end. Well, they did that, and then some. By artificially shortening the rear triangle, 'Dale created a rocket that lacked any semblence of comfort. I remember a lot of rides on mine that left my fillings loose and eyeballs vibrating–and that was with 25mm, cotton cased tires. I don’t think there’s a reasonable way to “soften” the ride on these.
Given the 2.8’s age (I think 94 was the last year they were made), you can probably find a CAAD 3 in either road or tri geometry that will offer a better ride for the same money.
Ride it, long, short, on the flats, on hills. Take your time before you commit to this one. I think Cannondale makes great bikes, but I also think they over-emphasized drivetrain stiffness over comfort in the 2.8s.
…My $.02.
Scott
I agree, you can find a better riding(like almost anything else) 
bike for the same money i am sure.
I owned a 2.8 in the past. I know it was the “multi-sport” geometry and think it was the 2.8 series. At any rate, the only thing that mattered was that it was the wonderful polished aluminum. I really liked the silver finish, the ride was tough (650 no less).
My bike racers would consider them nice crit bikes, but I think they can be decent bikes depending on intended use.