Glad you're okay, but what happened to you is the reason why I rarely and I mean rarely ever get out of my saddle. I had a bad accident on a friend's bmx when I was a kid, racing a cocky tomboy. We start, I almost get up to speed, chain slips and I do a GNAR-SIK skid on the ribbed rough concrete sidewalk with my right hand, left knee, and face. 20 years later, I still carry the nice scars from that incident and a weird sense of caution.