I have owned and rode various iterations of the Cannondale CAAD frames. I was a heavy guy at 210-215Ibs, but while the rides were stiff and I somewhat liked stiff frames, I just could not bear the continued beat-ups, especially as I aged. I have been riding CAAD frames as far back as 1998, so I feel I can talk a little bit about my progression from "preferring' stiff frames to now hating too stiff. As soon as I rode a carbon frame a reasonable distance, I was intent on getting rid of my aluminum frames. Carbon frames is all I ever ride now, and the stiffness and being not beaten up harshly post-ride offers a nice combo. Oh, I forgot, I still own a 1994 Cannondale Killer V900 aluminum frame, but it is mostly a beach cruiser these days. Believe me, there is something called "too stiff."

When Cannondale first stared supplying bikes to Team Saeco, they story was the riders were complaining that the bike is way too stiff.

It wasn't crashes that killed the frame, it was the thin aluminum on the seat tube. I kept pulling the front derailleur hanger out. Sweat would get down in between the the hanger, which was bolted on, and the frame. I solved the problem by using a gasket sealant to fill in the space between the frame and hanger.

Given that a frame could (not really, since we are ignoring all dynamics) be assumed to be a statically-loaded linear elastic member (a very, very stiff spring of sorts), a heavier rider would just 'preload' the frame a bit more and the result would be the same displacement over bumps as a lighter rider would experience.

Of course, this is a terrible model and I think it would be worthwhile to look into this question a lot deeper. Perhaps a simple spring (the frame) mass (rider) damper (tires/inflation, frame, you) system would be able to answer more questions.

If there are any suspension engineers here I would like to hear your thoughts.

Interesting. I usually would rust the stem bolt with sweat. But never got any on the FD hanger that I know of. Another common rust/corrosion spot was the first cable guide on the top tube. I think they were plastic on the Cannondale 3.0, no?

I agreed with the theory . I bought an aluminum bike from Pinarello years ago and I could feel every road bump . Sold it after one year .

That is what the LBS told me. Who knows for sure, though.