How long will it be before somone posts that horrible link to that guy?
Seriously, try not to fall. rolling out of a fall presumes that you're clear of the bike, and that's a big assumption.
for example, I crash on a skateboard, and the board stops, shoots out, whatever. I am now an independent body, able to roll, I hope.
or, I crash on a bike, and I'm still straddling the bike, or I have a foot clipped in, and now I'm trying to cushion my fall attached to my bike.