I've had several "incidents" while riding my motorized bikes. Once I biffed it while trying to do a 180 degree drift/u-turn. That wasn't so bad because I had full snowmobiling gear on and I just slid on the ice. Another time in the spring I turned on ice and fell on pea rock covered asphalt and just stopped dead. That one resulted in a broken pedal and some nice bruises regardless of the snow pants and jacket.
However, the most notable happened last autumn. I had just straight piped one of my 80cc 2-strokers and I had tons of low-end power. Top speed was lowered to about 20MPH, but it only took 30 feet or so to get there. It was the perfect set up for wheelies. So, after pulling it up a few times, I got cocky and started pulling wheelies out of the ditch and on to the road. I was trying to see how long I could ride them. Needless to say, that didn't end well. I had one wheelie get away from me and I decided to bail when the handlebars were level with my head. It all went downhill after that. I was wearing jeans, an insulated flannel shirt, regular tennis shoes, my Polaris snowmobiling helmet, and no gloves. Honestly I didn't even get any roadrash. I've trained myself to tuck n' roll instead of putting my hands out. Anyways, I tripped up on the landing and majorly bruised one calf, twisted an ankle, and tore the ligaments in my left foot. I was stuck in bed for the better part of three weeks (Mass Effect 3 to the rescue
) and had to crawl to get to the bathroom. It really sucked not being able to walk.
That's why I'm planning on getting some rigid soled boots, but really the one thing that has saved me time after time was my full face helmet. Those crashes would have all been 10 times worse without it. Crashes on bikes always seem to end with your face planted into the ground. Also, take it from me, don't think you're Superman either just because you've got a full-face helmet.