That is actually a good failure rate over multiple model years.
No, it isn't. We do 3 mtb brands and 7 road brands. Cannondale dual sus MTBs and road bikes have the highest return rates. They vary from 7% to 60% in the first two years. Colnago is the best in terms of return rates (we have not seen a structural warranty in 14 years on a lugged Colnago, and have only seen two warrantable issues on monocoque frames, with over 200 in the field in the field under warranty [two years]). Trek are significantly better (~1% return rate per year). I keep the statistics over the first two years of the life of the bike, since that is the shortest warranty period of any brand we have (Colnago), and since we review the brands we carry every two years.
I can see and hear complete opposite of what Tokyo Drifter writes. I have seen old CAAD frames that did over 100,000 kms and they were perfect with lots of life left. This, to me, is total BS what he says.
I wonder if this guy is one of those paid posters...
I am giving you my opinion based on a far larger sample size of bikes than you will ever personally have access to. We sell ~1800 bikes/year, which means we have ~6,000 bikes in the field, owned by their original owners, under statutory warranty. Your best mate's Cannondale could have a million miles under it, but that is a statistically long time for any bike to last, and particularly long for a Cannondale.
I do not know what motivates your last comment? I have told you that I think they are great bikes. I own one. I rode one before I worked in bike shops. I am trying to offer an informed opinion, but that seems to grate a lot of people. All I am saying is that, in my informed opinion, older CAAD frames are not a good purchase.
I would buy a Six 13 or a Taiwanese made Cannondale, if I were in the market for a used Cannondale. Post 2010 Supersixes are well made, and the CAAD10s have had a lower warranty return rate in the first two model years on the market than any of the US made CAAD bikes. The US-made bikes are cool, and I would get one. However, I wouldn't pay much for it and I would have every expectation that it could crack on me, but then it would look cool on the garage wall.