I wrecked an aluminum CX frame a few years ago. A homeless guy jumped out in front of my path one day, on a dark, rainy, late winter ride. I wasn't sure the brakes would stop me before I hit him, and he froze up, like a deer in the headlights. I swerved out of the way, but in the process, I hit my chainstay against ... I can't remember, it was a sign post or a fence or something. Yeah, rider stupidity was involved.

I probably hit the stay going about 5 mph, but it dented. Two bike shops told me the frame was toast. It cost $400 to replace it. Took a month, too, and it was a crappy month without a bike.