This keeps coming up! That and the argument that the primary (downstroke) muscles are the strongest and most efficient and that we should not waste or time and resources on the others (the muscles for pulling up, over the top and back along the bottom).

I used to race. I've been riding a long time. Being told and taught to "spin circles", ie power continuessly around the circle was one of the biggest gifts I got from those days. Still, 40 years later. I spend a lot of time riding the old setup of toeclips, toestraps pulled tight and slotted cleats. When I forget to pull my straps tight, I regularly pull my feet out. Not just standing for hills. If I don't pull the straps all the way tight, I often here the click of my cleat coming down on the pedal every stroke because I lifted it off coming up.

There are two places where this really pays off. When I need all the power I can get and late in hard rides when I am near fried. I have more power I can dip into and for those marathon days, being able to ease off a little on the big muscles for the early hours pays really big dividends when I need them many hours later. Plus I have a better ability to keep my feet moving in circles that the guy who has been just pushing for those long hours doesn't. I'm the guy who drops them or drags their butt home.

Ben