2014 Ridley Helium(lightweight climbing bike.) After about 6 years of riding, it developed a small crack at the back of the drive side chain stay. It was almost invisible from the outside...the only thing that clued me into something being wrong, was a horrendous creaking noise that it developed. Saw a very faint crack in the paint, pulled the rear derailleur cable out and could see the crack well from the inside.
I think it was a perfect storm of factors leading to the crack. The lay-up of the carbon on the inside of that frame is not impressive. I also crashed that bike a couple years previously. ******y brag-time, but I do put out some pretty decent wattage(not a flyweight climber though.) I think a smaller rider may have never experienced the same issue, watching the bottom bracket area flex while pedaling was always a bit disconcerting.
Anyway, I ended up on a brand new Canyon and never looked back. While I've only ridden the Canyon for 3.5 years, I've put considerably more miles on it than I did in the 6 on the Ridley. No issues so far and it has re-affirmed my faith in carbon not assploding.