True- but again, it's a zero-net-sum gain, because all they are doing is reducing the resistence of the downstroke pedal; so any gains they make on the upstroke are just making other side's pedal easier to push down on- more force on the upstroke- but less force on the corresponding downstroke. If this weren't so, there'd be a ton of evidence showing substantially performance with clipless. But there is not- and the above is why. It's just simple physics.