Originally Posted by PenguinDeD
I believe CAAD4 is from the mid to late 90's...what year it was phased out I'm not sure. Hopefully the bump leads to some better answers.
I have a CAAD 4. It's just a CAAD 5 with a standard headset rather than a integrated headset (geometry is exactly the same too). Some people actually like the CAAD 4 more than the CAAD 5 because of this. I'd still take a CAAD 5 though, I don't think integrated headsets are a negative.
The CAAD 4 has the curved seat stays like the CAAD 5, the CAAD 3 doesn't.
Big difference between the CAAD 4 and CAAD 3. They are two different generations of frames rather than just tweaks like the difference between a CAAD 7 and CAAD 8 (that's the next generation up from the CAAD 4/5)
CAAD 6 was some kind of in between model. They didn't make very many of them (very rare). I forget which group it fell into.