No - they just didn't release as I was launched forward. The bike had stopped dead. Because of the direction I was flying, the pedals didn't let go. Had there been an instant to realize what was happening, maybe I could have rotated my heels outward to unclip, but it was all in a flash, with (as I recall) at least 2 distinct impacts among the bike, the tree, and myself. Anyway, no, the pedals didn't cause the accident, but they did break my ankle. Rather, they didn't cover for my own stupidity .