Originally Posted by Leinster

Disagree, on both counts. I've been consciously upstroking on steep, out-of-saddle climbs since I first rode with clips-and-straps when I was 13, to the extent that I now do it unconsciously and my foot comes away when I climb out of the saddle on platforms. You can tell with runners and clips because your foot lifts off the pedal and pulls on the strap. "Plain old body mechanics" tells me I can lift my leg just as well as I can put it down; that's how I climb stairs. And I could climb stairs with 20lb weights around my ankles if I had to. I can exert more power on the down stroke, sure, because my leg lifts 185lbs every time I go up a step, but to say my body is "not capable of making very much upstroke power" is just not true. Even if my upstroke only generates 10% of the power of my downstroke, to ignore the upstroke is to deny myself that 10%.

The pedals are at rigid 180deg, but that doesn't mean pushing on one prevents pulling on the other. Watch some Yacht racing on youtube. The guys hand cranking the sails in and out, as they get to the end of the line down to the 60rpm range they'll be pulling hard up on one side while pushing down hard on the other, they're leveraging one side against the other. No, arms aren't the same as legs, but the 180deg crank principle is similar.

And there's a clear difference between unloading the upstroke, loading the upstroke, and counter-loading the upstroke. One is riding with flats, the 2nd is climbing with foot retention, and the 3rd is a track stand.