The idea makes sense, but I don't know about the numbers.

I'm one of those slow-but-steady types. An all-out sprint for me is some people's marathon pace. But 100 miles on a bici has never really been a big deal for me. My natural cadence has always been in the high 80s. When I put on my first cadence monitor in 1985 that's what it was, and even though I normally try to keep it a bit higher (like, low 90s), that's what I revert to when I'm fatigued.

Then you look at pro riders, and see cadences much higher. As someone was pointing out, track riders (probably the most fast-twitch of the bunch) keep cadences of 120+. Lots of road racers have a natural cadence right around 100. That's kind of where I came up with the range of 85-100.

I think for a new rider, the question is (1) lessening the shearing forces on the knees, which for a lot of people means learning to increase their cadence (less power per pedal stroke at any given speed) and (2) learning to pedal smoothly. I don't for a minute think that everyone (or anyone, really!) should maintain a cadence of 140 all the time, but I strongly believe that everyone should be able to maintain a cadence of 140 for 60-120 seconds, without bouncing. Learning to do that will teach you to smooth your pedal stroke at any cadence. It's easy to pedal in squares at 70 rpm. Not so much at 140.