Could this be done by bicycle by a 70-year-old? Initially, I thought it would have required a car with a driver, but if the run portions were short enough, it could be done with a bicycle, especially if the runner was a triathlete, like FM. Here's how.
Park bike 1/8 mile before the mat. Enter race at the time to hit proper split
Cross mat... split time starts.
Run 1/8 mile... elapsed split time 1 minute
Easy run/jog back to bike (now 1/4 mile away) 2.5 min... elapsed time 3.5 min
Bike 3 miles to 1/8 mile before next mat at 15mph (12 min)... elapsed time 15.5 min
Walk to next jump in point 60 seconds... elapsed time 16.5 min
The runner has 3 minutes to wait before jumping in and running 1 minute to hit next mat at 20:30ish
If you increase the distance before the mat to 400m and after the mat to 400m, then the runner would hit the next bike parking area in about 18.5 minutes, walk 30 seconds to jump in point, wait 30 seconds and run 1 min to the next mat. It would still be possible, but that would be cutting the margins for error very close. I doubt if he ever ran this far.
Realistically, if a bicycle was used, then the jump on and off the course would need to be within a couple of hundred meters of the mat. Definitely doable if the running portion is kept this short.
However, a car with a driver makes it easy peasy.
While doing it alone on bike is the simplest solution, I’ve been open to an accomplice theory for a few reasons. I admit that a bike limits risk of a traffic problem and does not require him to find a accomplice, so all things being equal it would be the ideal way to cheat.
I once biked along with my wife while she ran Chicago in about 3:20. Of course I didn’t go on the course. I stayed on sidewalks and parallel streets. It was a nightmare. Much harder than I anticipated. Perhaps people who have done or spectated L.A. would say that it would be easier there, with fewer spectators, wider sidewalks, and accessible parallel streets.
The hardest part about following her was the first few miles. That’s why I wrote that FM’s biggest challenge would be getting from the start to 5k in the right time. But if there is a shortcut that reduces the distance significantly then maybe that isn’t so hard.
Finally, why did he have the chip on a lanyard? To pass it off easier? To avoid an accidental tripping of a timing mat?
Just thought of something... what if you were really ambitious and used a few bikes, locked up the night before, so you never have to backtrack to get the one you just used? No, I don’t think he did that. But it would be some next-level cheating! Ride bike, ditch bike, cross mat, carry on, get next bike, etc. You could Pony Express the course.
I'm not questioning that it's absolutely possible he had an accomplice, but why the hell would someone go along for that ride? The only circumstance I can reasonably fathom is one where the cheater is paying a bib mule for the assistance, or some type of quid pro quo. An accomplice would certainly make it easier to transport a bike around and workout logistics.
In such a scenario, it'd be sort of like those run/bike relay races, where teams alternate between running and biking an entire course. Basically, a team member hands off the bike to the finishing runner, who bicycles to the next check point, and waits for the runner. In these races, some teams have a trailer attached to one of the bicycles to help transport an extra bicycle around in case of an emergency.
It's also conceivable that the cheater is solo. The cheater lines up at the start of the race and rapidly falls behind, perhaps pretending to have equipment issues (untied shoe (in mass starts, heels are often caught/runners tripped up and shoes lost), etc) and falls off course shortly after the start. The cheater grabs a bike and rides to the 5K timing mat and enters the race for the check point time and photo ops. Rinse and repeat. At a modest bicycle speed of 15 mph, it'd only take the cheater 12 minutes to get from the start to the 5k mat. Based on the relative lack of sweat/exertion displayed by this accused cheater, I'd have to imagine they'd be using a bicycle with a support motor, making it extremely easy to bicycle 20+ mph from check point to check point.
If the cheater has completed a number of triathlons and duathlons, they'd certainly be skilled enough to navigate the transitions seamlessly, and that'd probably be where they got the original idea of how to pull off a great marathon cheating feat.
I'm not entirely familiar with bicycle rentals, but do any of the companies provide swipe card to access bicycles?