Wild ass guess from watching it only once. May have shifted his chain into the spokes causing the deraileur to spin around. I think I saw that part happen. (I have done that). He got a quick bike from teammate, then probably got a change from the team car. Bummers none the less. G

I think its a little hard to say exactly. But, it looks like prior to it happening his shift wasn't catching. So I'm guessing he maybe powered through a mis-shift and did it that way. Here's a thread over at weight weenies where it happened to a guys cr 1 :( They will give you plenty of options to choose from. http://weightweenies.starbike.com/phpBB2/viewtopic.php?t=6013&highlight=catastrophic+failure