Originally Posted by
sac02
I wrote this a couple years ago for the FGSS forum:
The brake-equipped bike can’t really decelerate quite that fast. Substitute this deceleration, a/g = 1.17, into eqn3 and you will see that the weight on the rear tire is negative – huh? In other words, the rear wheel has come off the ground and the rider has (possibly) gone over the bars.
The front flip was accounted for, as you see here. The trick is that once the rear comes off the ground, the CG is going up and the weight bias is going forward. What would you guess this is going to do for our hapless rider? Nothing good, that's for sure.
I've gone over my handlebars twice with a locked front tire. Once when I was a kid and once in a race when a guy crashed in front of me (right in front of me). When I was a kid, I got a bag (with my little league uniform in it, no less) caught in the front wheel/fork. I went up and over so quick I never knew what happened. Front wheel didn't skid. In the crit crash, I was on my brakes super hard and doing about a 45 deg. stoppie when I hit the guy and when the rest of the way over. Again the front tire never broke traction.
For the most part, we're not traction limited as much as we are limited by vehicle dynamics. The physics of the situation just isn't in our favor. For anyone that thinks they can brake 'almost as good as a car', I feel sorry for you and the crash you're liable to have.