I posted this in part to the "Did You Ride Today" thread, but that's not really a way to get a response, so here it is again, slightly longer.

My road bike was in the shop last week, so I was riding my commuter for non-commuter rides, which has strapless steal toe clips. It's a slower bike with a much more upright position, but I noticed that I maybe had more power on modest hills than with my "better" bike. I got to thinking about it and thought I'd experiment with my foot position. On my road bike, with SPD pedals, my foot is generally all the way back (meaning the cleats are all the way forward). So as an experiment, I moved the cleats to an intermediate position. I took an easy 20 mile test ride (no hammering) and this seemed to be fine, though I wasn't entirely sure that it was an improvement either.

So the next day I went on a 75 mile route with some more demanding riding, and my legs were were really hurting me, particularly for the first 30 miles. It wasn't the normal fatigue, which I feel chiefly in my quads, but rather in the upper part of my calves and the upper inner part of my thighs.

Could the change in cleat position really make that much difference? If so, will I get used to it quickly and be better for the adjustment? Or should I just move the cleats back to the original position?

And to the original question, do any of you think that cleat position makes a big difference to your efficiency and power?