Chris Swrote a review of Rotor Qarbon Aero Outer Q-Ring - Shimano on July 29, 2017
Familiarity: I've used it once or twice and have initial impressions
With round rings, we tend to compensate for the dead spot by ankling or doing that scraping motion with our foot. This produces that beautiful "circular" pedal stroke that we all want, where even in the dead spot there is power being produced.
What q rings seem to do is mechanically render the ankling and scraping unnecessary, thus simplifying the pedal stroke. The legs seem to move more like pistons on these rings. They don't feel as weird as they look, at least to me. Instead, the pedal stroke feels beautifully smooth. I run a round small chainring, and when I drop into it the pedal stroke turns and feels ugly and I have to actually think about how I'm pedaling. But with q rings, you don't have to do that.
I'm not sure I buy the marketing, which implies that you'll be stronger across the board. It seems more plausible that the benefits you get from these will depend on how bad your ability to pedal smoothly and in circles is. In a bike race there are many situations where the pedal stroke can get compromised and you lose efficiency: standing efforts, sprinting, being tired, hard efforts. Or if, like me, you just have a naturally inefficient pedaling style. If they do make me stronger otherwise, so much the better, but if my explanation of these rings is accurate then I should be at a competitive advantage over equally strong but tired racers pounding away inefficiently on round rings.
There is a downside over the round rings, which is the shifting from small to big ring. That may be a function of having a round small ring, but I think it's worth the tradeoff until I get the inner q ring. Whether it's aero or not, I really can't tell. But the qarbon finish really looks cool.