One. Last November 1st. Had to move off a road onto some grass due to cars too close to the edge of the road. When coming back on my front wheel caught edge, twisted and sent me over the bars onto my head and hip. Ouch! I remember feeling my head crushing the foam and thinking "thank God I was wearing a helmet" as I had not usually worn one and only put it on because of damp weather. The other point is it hit at the rear of my head just to the left of that pointy bump. I credit the fact I was wearing a skater style helmet for covering that area. $40 Bell Faction btw. Cracked outer shell and liner. Will post a pic if I can get it off my phone.