700x23 Continental Ultra Sport tires. I didn't go back to see what I ran over. I don't think it was sharp. Seemed like a 4 inch diameter rock or log. I guess a pinch flat in the rear is kind of weird. Maybe I'm wrong. I haven't disassembled it yet for the final failure analysis.

I don't think kevlar belted tires help with pinch flats do they?

It was a pretty violent bump. I hit something big. Not paying attention again. Seems to be my biggest problem.