bike senario is easy. I've watched it many times and biked the streets. without a number on no one is looking at you or cares, as why would they?
then bike to another checkpoint, knowing approximately what time that you have to get there and walk across as you're looking backwards for a friend to come by, or whatever.
how to combat this, easy!!!! Every checkpoint should have spotters, over a dozen of them. If anyone gets near the mats and has no number, yell out to them and stop them. The spotters are on the ground in front of the mats. If someone is brazen enough, grab them and see if they have a number (get that number!!!!!) Make them expose their number or take their number off just like they have the right to do if you're in the wrong coral at the start.
he did it like I just said above and the picture that someone posted early on proves it. he could have had a rented car at a certain point and then abandoned the bike....aka left it wherever as it happens every year...too many bikes as they are everywhere.