I know why I fell
Holy crap, I fell off my bike yesterday because I didn't think through the physics. Before I went out, I knew that with the icy conditions there was a significant danger that I might lose traction and not be able to stop myself from running into something. I was being careful about that sort of thing. But there is a more subtle danger that got me which never even occurred to me.
I was thinking back on it, and I suddenly realized that there was no possible way I could have fallen off my bike the way I did unless something really strange happened. When your wheels are spinning at normal biking speeds, the only real way you can fall is over your handlebars unless an enormous amount of force acts on you sideways because the angular momentum of your wheels resists the changes in your direction about any other axis. But in my case there was no large force but my bike still spun and fell sideways while I was on it. Neither the spinning nor the falling should have been possible.
And then I realized what must have happened. When you have no traction, any application of your breaks causes your wheels to stop spinning immediately. I don't even remember using my breaks, but I must have gotten nervous about something and tapped them while I happened to be on top of ice, so I lost my angular momentum instantly and there was nothing left to hold me up or keep me oriented straight.
Let this be a warning to everyone. It doesn't matter if you are in a car, but if you are on a bike or a motorcycle and you lose traction, whatever you do, don't use your breaks. Hell, come to think of it, the only way you'll know you've lost traction will be if you either a) try to turn but keep going straight, or b) you do what I did and fall. So I guess you should just never bike or motorcycle in icy conditions. Maybe everyone already knows this and this is old news, but I don't think I've ever been warned about this danger.
I was thinking back on it, and I suddenly realized that there was no possible way I could have fallen off my bike the way I did unless something really strange happened. When your wheels are spinning at normal biking speeds, the only real way you can fall is over your handlebars unless an enormous amount of force acts on you sideways because the angular momentum of your wheels resists the changes in your direction about any other axis. But in my case there was no large force but my bike still spun and fell sideways while I was on it. Neither the spinning nor the falling should have been possible.
And then I realized what must have happened. When you have no traction, any application of your breaks causes your wheels to stop spinning immediately. I don't even remember using my breaks, but I must have gotten nervous about something and tapped them while I happened to be on top of ice, so I lost my angular momentum instantly and there was nothing left to hold me up or keep me oriented straight.
Let this be a warning to everyone. It doesn't matter if you are in a car, but if you are on a bike or a motorcycle and you lose traction, whatever you do, don't use your breaks. Hell, come to think of it, the only way you'll know you've lost traction will be if you either a) try to turn but keep going straight, or b) you do what I did and fall. So I guess you should just never bike or motorcycle in icy conditions. Maybe everyone already knows this and this is old news, but I don't think I've ever been warned about this danger.