How-To: Free motion cycling rollers

I just got one of those indoor bike trainers. You know, the kind that props up the rear wheel against a heavy, resistance-providing wheel. The front of the bike rests on the floor, the rear axle is pinned, and there’s no balancing required. I didn’t think of it at first, but that’s not really how you ride a bike in real life, and therefore must not be good enough for athletes training for more than just a good indoor cardio workout. Instructables user pennachi1 created this indoor cycling rig that lets you actually ride your bike the way you would outside. Looks a little scary to me, but I’m informed it “works fantastically!”