From what I could tell, his rear tire seems to have shredded. I saw chunks of it when the traffic slowed down. I was trying not to rubberneck. An officer was helping the rider. He was on the ground but moving. His bike was some 100 yards further up and there wasn't much left of the rear tire. I'm glad the guy is alive and seemed ok. Seeing him on the ground gave me second thoughts about riding with jeans though. It was a sobering sight. Ride safe. Jack