I was driving in traffic all going about 70 mph. The car in front of me was maybe 15 to 20 car lengths ahead of me. The car had two bikes on a bike rack. One of the bikes fell off the rack right in front of me. The bike bounced in my lane, then bounced in the lane to my right, then onto the guard rail on the right. The guy who dropped the bike kept on going, no brake lights, nothing. I could not catch him, he was going a little over 70, and traffic was in the way. I also realized that to catch him I had to be behind him, while there was still one bike on the rack. Hope it was fastened on somehow. I thought about calling the cops but he was a long way away by then.