My understanding of how oval rings work, which could be totally wrong, is that just as you are heading into the power portion of the pedal stroke (what for me is around 1 o'clock), the chain should be at the tallest portion of the oval. Then you spend the power stroke pulling that tallest portion up, around, and through. And since the chain is in the taller part of the oval, you spend a little more time in the power stroke (on a 52t oval ring, the taller portion is more like a 54t-ish ring, depending on the percentage of ovality). After that, right when you are heading out of the power stroke (into the "dead" spot), the chain is moving into the shorter portion of the oval (that 52t oval ring becomes more like a 50t-ish ring) and you move through the dead spot just a little faster, while the opposite leg is about to head into the next power stroke.
I used a set of oval rings with a fairly mild 11% ovality for years, when I became curious about Osymetric rings ("If a little oval is good, would more oval be better?"). I mounted them the same way I had been riding the other rings, and my pedal stroke was immediately wonky, which affected my bike handling. I gave it a few you-just-need-to-get-used-to-it rides, but the pedaling dynamics never improved. "This is wrong," I concluded, and did some research, coming across what I describe above. Based on that, I remounted the rings (which turns out to be the way they were intended for a df bike), my pedal stroke smoothed back out, and I even gained a little more speed on my V than before. Just to be sure, I rotated the rings one stop each way and tried it out. That df mounting position was definitely the best spot, which makes sense to me because a CB rider's body position is similar to a df rider's, with the whole thing--rider and drivetrain--rotated 90 degrees counterclockwise (or, if you rotate a CB rider and drivetrain 90 degrees clockwise, he or she will be in a surprisingly df-like position). That the chainring would mount the same way makes sense.
Did that mean that I had been riding those 11% ovality rings mounted incorrectly all those years? Yup. I ultimately did not keep the Osymetrics. I liked the idea, but for me the ovality was a little much for my physiology and riding style (at 5' 5", 130 pounds, I don't quite have the uumph to take advantage of that much oval). When I remounted the 11% rings, I did so in the intended df bike position--about 90 degrees different than before--my pedal stroke went from smooth to smoother, and my average speeds got a small boost without any increase in perceived exertion or fatigue.
Osymetric makes it easy on a person by having only five mounting holes for a five-arm spider. Many Rotor rings, however, come with several mounting holes. So many fine-tuning possibilities! I tried all five of their recommended locations, and ended up in spot 4.
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