I took the challenge this past Monday and can say these workouts from fasttandem is tough.
The setup included: my Quintana Roo Kilo on a Cyclops Fluid2 trainer, a water bottle filled with water and 2 teaspoons of apple cider vinegar, and the boom box set to play Red Hot Chili Peppers - Stadium Arcadium.
I began the workout with a short 6 minute warm up and then continued into the intervals of trying to spin at 100+ RPM at various gear ratios. To spin with the gears at 53 x 17 for four minutes requires a mind, heart, legs, and lungs of steel. I guess I don't have any of them just yet, because I averaged about 80 RPM during the 53 x 17 four minute interval. Maybe after completing more and more of these workouts I might be able to keep pace, I hope.
The Cateye bike computer reported the following:
Max speed 27.8 mph,
Average speed 18.9 mph,
Distance 18.0 miles.
Oh, after the challenge I ran barefoot on the treadmill for an easy 2 mile run.