“What happened? Apparently a hairline fissure around the carbon bike fork failed, and the fork bent and locked up the front wheel without warning. (Yes, I know I should inspect the bike thoroughly each time I get on, but the crack was invisible.)”
I was returning from a job in Tracy CA one day, driving down one of the main drags there, and watched a guy biking at a good clip up the street in the opposite direction.
All of the sudden it looked like he hit an invisible force field or brick wall. I was shocked, I knew he was hurt, I flipped a U in the street traffic and went back. His face had taken to the pavement like it was a large pencil eraser trying to delete wording on sandpaper.
I was looking around and he, coming to his senses and becoming coherent, noted that he had his sweater slung over the handle bars and an arm of it had flopped free and upon falling into the front wheel instantly pulled the whole thing down into the front brake assembly and stopped forward momentum.
It was one of those kind of bike wrecks that makes you hurt just to see it.