Commuting 3-4x a week for 4 years now. 1 accident, 2nd week I was commuting - a car was following too closely on my left rear and wouldn't pass. I was so busy watching it that I did not see a pothole. Inexperienced as as I was, I shifted my weight forward instead of back and went over my bike as it stopped. I had also left my gloves at home so tore the hell out of my hands, road rash on both legs, etc. Didn't hit my head and the idiot in the car stopped instead of running me over.

Commute is 10 miles each way, minimum.