I saw an old man on some kind of motorised chair tangle with a kid on a bicycle once. They were both going for the same slim chance in traffic and the old man went at an angle while the kid was mostly airborne, jumping a curb at his best speed. There was a drainage dip right there and the kids always nail it, but usually without the feeble in their way.
The kid's back tire clipped the old man's handlebars and down they went, in front of oncoming traffic. I was about three cars back, waiting to turn, but I could see well what had happened. The kid's bike kept on going and a car ran over it without even stopping. Another car slammed on its brakes and stopped just in time to keep from hitting either of them.
They were both very lucky. The kid bounced up from his nastily roadrashed knee, but the old man just laid there in a daze.
Everybody just drives too fucking fast around here!
Unfortunately, there are places where those kind of chairs are not allowed on the sidewalks, so they end up driving down the streets at seven or eight miles per hour.