I've about 60 miles now on the SPD-SL's, moving from loose toe clips and tennis shoes, and always was toe-down push forward pedaling. Now with the clipless, Flyingblind9 noticed I'm dropping my heels, possibly even past level on the backside of the stroke, and my leg gets straightened out.

I'm pretty comfortable right now with seat height and fore-aft position, able to spin even 110 + without bouncing if I concentrate. The shoe cleats are initially in all-back position, so the pedal shaft is behind the ball of my foot, and have not tried moving the cleat forward yet.

Is the problem just technique, or are there fine adjustments to the cleats or seat positioning that contribute to technique? The part that surprised me is toe-clips was toe down forward push, and clipless is heel down in back and (wonderfully) full circle pedaling.

So....is this just one of those so-boring-threads or what?

Have you read Steve Hogg's blog post on pedaling style?

PEDALLING TECHNIQUE ? Which is best? » Bike Fit » Feet » Steve Hogg's Bike Fitting Website

Wow. Thanks for the post and links, Dunbar. I thought I had a totally twilight-zone thread. I'll go read the post. Appreciate it a lot.

Really interesting blog post. Thank you for linking!

I would point out that everyone who has ever learned to ski well knows that Mr. Hoggs opinion of how the CPG functions is incorrect. We program our CPG with our conscious mind. After enough massed practice, it will perform the practiced movements on its own. And even after this point is reached, those "unconscious" movements can still be reprogrammed into the CPG by the conscious mind. In the same way, one can modify one's pedaling technique, and in fact it will not break down under stress. Yes, it will change under stress because it has to, but the manner of this change can also be programmed in by mass practice. The secret of champions is that they pay attention. always, to everything.

It's all about skills. This is the best video I've seen about this subject:
Pedaling Efficiency.wmv - YouTube

Answering the OP specifically, IME the most comfortable and efficient fit will have your foot flat at the bottom of the stroke. One still has to find the amount of leg extension which will produce the most power with that flat foot. This is where a pro fit with a power meter and/or lots of experience comes in.

IME the best way to develop a good pedal stroke is to spend a lot of time on the rollers, concentrating on making a steady hummm. Engineering-wise, you want the sum of the moments on the bottom bracket to vary as little as possible during ordinary pedaling. Which, as Mr. Hogg points out, does not mean pulling up forcefully on the backstroke. Also, as Mr. Hogg points out, the psoas are weak, ineffectual, and don't fire at the right time on most people. Contrary to what he asserts, I've found that one-legged pedaling on my rollers is the most effective method of getting all one's leg muscles to fire correctly and at the right instant. Lots of it. I do hours of it every year. OLP drills allow one to concentrate on one leg at a time, getting the motion just right without the interference of the other leg. I just did 7 X 2' (each leg) one legged intervals on my rollers this evening. It's my favorite Tuesday recovery technique after a brutal Sunday ride. It's good core work.

A simple way to get started on a good pedal stroke is to concentrate on pedaling with one's shoe heel cups.