FWIW-I tried oval chainrings for a few months last year…didnt notice any differenc in speed or power. I DID notice that my pedalling did not feel as smooth so I reverted back to round chainrings and will never go back to oval. Now for my real question…
It just seems that the claims of oval chainrings would only be possible if your pedalling action was in an oval pattern…and each side independant of each other.
You could have square chainrings…and your feet are still going in a circle…but you would feel the resistance of the corners, which would slow you down. Which is why we dont have square wheels…ever…and a perfect circle is always the most efficient. There are mechanical advantages to be achieved with oval rings…but they seem to ONLY be possible if the crankarms are able to change lengths AND are independant of each other.