I've always been the no-helmet type, always had one but prefer not wearing one.
One day heading into SF after dropping my girlfriend off at home in salinas, She said I should wear the helmet, so to make her happy I put it on. Got almost into the city, and went to pass a semi, when I got closer to it and started changing lanes I noticed something white between the rear duels on the trailer, got perfectly in line and it cut loose, it was a chunk of concrete bigger than my fist. Hit my helmet right above the eye, snapped my head back with enough force to make me loose my grip on the bars. Only thing that kept me on the bike was the b-bar, I mean it laid me right down on the seat, I was eeing stars big time, managed to get back upright and grab the bars before I hit the shoulder, stopped the bike and shut it down. My ears were ringing, my vision was all crossed up, my neck was all locked up, from snapping back then hitting the b-bar, I ended up sitting there for over a half hour till my head cleared.
Cruised over to SF general, and got checked out because my ears were still ringing and I was having a hard time keeping my eyes focused. no damage, but the helmet was toast, new at the time Bell fiberglass with a big gouge taken out of it, and cracked down to the opening.
Closest to real injury I've ever been on a bike without once hitting the ground.
Now if you want a laughable accident, (now, but at the time it was painfull) I was running my girlfriend home one night (after moving up to michigan) and since we were running late I took the most direct route which is a somewhat twisty and very isolated dirt road (that is dirt, not gravel, what they call seasonal roads up here, but honest states call them firetrails )
Anyway, came up to a curve and saw a black 'lump' in the road,couldn't make out what it was so I angled off to miss it, got closer and saw it was a porcupine, only doing about 35, so I checked it out as I went by, when I looked ahead again, there were two more of the things in the road right in front of me, I hit the one with the front tire, which knocked me over far enough that I hit the other one with my leg and foot, got the bike straightened up and stopped so I could look at my leg which seriously paining me, looked and I had about 40-50 quills in my leg and boot, tried to pull them out and figured I'd tough out and ride to her house where I could actualy see what I was doing, fired up the bike (only time I realy NEEDED electric start) and put it in gear only to find out I had a flat tire with quills stuck through the sidewall.
I couldn't walk with all the quills in my boot so I started pulling quills out with pliers, and found out that I couldn't get all the quills out of my foot without pulling my boot off, and I couldn't pull the boot off without getting the quills out, so I ended up having to pull all the quills I could then cut the boot off and pull the ones that were buried. 4 miles to the pavement, and roughly a mile after that to the first house, and nobody was home so we had to go to the next one before we could get ahold of someone to come get my bike and get her home. ended up getting her home at around 6:30.
Only time I'd ever seen a porcupine in the wild, and they screwed my whole day up.
Ken.