Originally Posted by slide
I don't see how the chain locked the rear wheel so I'm saying it was the brake. After all, if the chain jammed locking the rear wheel, the rider wouldn't THEN put on the rear brake so I reason that the rider wasn't sensing a locked or dragging rear wheel when he put on the brake.
No, no, not that simple. Chain coming off doesn't ALWAYS lock up the rear immediately. So chain comes off, bike is still rolling, he waves, starts to brake. You can see this in the video. The chain is off first, then the brake light comes on.
THEN a second later the chain gets caught, locks up. After the bike takes a tumble and the wheel isn't turning forward any more, the chain comes loose again.
It's possible and I'm willing to give him credit for that being the scenario. Otherwise there is nothing about the chain being off that would motivate someone to lock up the rear brake. The wave (for whatever reason) which came after the chain was already off, indicates that he was hardly in a panic.