Looks like a pretty high percentage oval on the bigger sizes anyway. I won't be finding out since they only make it in 110BCD apparently

Our study showed non-circular chainrings to have no effect on maximal power.
http://journals.humankinetics.com/...0035?journalCode=jab

There are other reasons to use oval chainrings beyond maximal power. Maybe not universal, but we are individuals that have certain traits. I see oval chainrings as I see orthotics. They do not produce gains for everyone, but they do for those that have a deficiency or characteristic that makes them suitable for the device.

Some examples that apply in my case are the following: sparing injured knees or producing higher average power in situations with low inertia such as in a climb.

Nope, they don't. But that's a pretty narrow window to define a study.

For certain people, they'll help provide a higher average power under circumstances like a climb. I use one on every bike I own. Anecdotally, I've found that I perform better with one. Took awhile to get used to, but once I did...

Yeah, this is my case (though I would like to see a study about running off the bike but those are already pretty messy).

I have different leg lenghts and I have gone back and forth on certain shims bc they effectively make your crank longer at the top and shorter at the bottom but at about 1:30-4:30 it is negligable and hence why i want to try having the leverage in that window.

There is a long discussion on this topic in this thread and I have pasted a couple of my posts below. http://forum.slowtwitch.com/...F_P6484366/#p6484366

The study I cited is the first part of Chee Hoi Leong's dissertation. The second part was on metabolic cost / efficiency during submaximal cycling. That second paper should come out within a year or so. Those of you who are dying to know the submax results can search for his dissertation document on line (you'll find a link in that thread).
Keep in mind that non-circular chainrings have been around for over 120 years. If they actually worked either 1) they would be banned or 2) everyone would use/produce them. Since neither or those is true after over a century I believe its safe to conclude that they don't improve performance except by placebo effect.
Our data demonstrate two reasons WHY they don't work: First they attempt to change kinematics in the wrong way so that if they did have an effect it would be to reduce power. Second, cyclists make a subtle change in their ankling action which prevents the effect of the chainring from reaching the knee or hip (where most power is produced). They don't affect your muscular actions so they can't do anything.
How come lots of people believe they help? My sense is its pretty simple. If you happen to be having a good fitness day the first time you ride them, you may be inclined to attribute your good performance to the chainring. Those having a bad day might conclude they suck. Those having an ordinary day will believe they don't do anything. Of course there is also a large "belief" factor. If you believe, up front, that they will improve your performance then they very well might. If placebo wasn't important we wouldn't have to control for it.
Ride em if you like em. They won't help but they don't hurt either (except in terms of $$). Unless of course what is true for a group of experienced cyclists doesn't hold true for you.
Cheers,
Jim

Within your last sentence lies the answer. Group and Experts are they keywords. Not everybody shares common traits with that group, nor is everybody an expert. If you get the exact same group of experts and have them use a 5mm heel raise in their right leg for running, the conclussion may be that 5mm heel raises have no efect in running whatsoever, beyond a placebo effect. Except, if you have a 5mm shorter leg that is.

I see oval chainrings in the same way. I have bad knees and weak hamstrings. Both make going over TDC harder than for that group of experts, that is why it has no effect on them, but it has on me.

Belief is powerful. As is belief in one's own uniqueness.

Almost as powerful as common sense, the least common of all senses.

Regarding belief on one's uniqueness, you are not referring to this? https://www.youtube.com/watch?v=jVygqjyS4CA
Right?

https://www.youtube.com/watch?v=C9iDBkJqxNg

Like faith that a study carried over around 30 individuals allows you to extract conclussions applicable to mankind? You sure need a good dose of it.

Most humans have similar muscles, which produce torque about similar joints, and make use of similar central pattern generators, all of which evolved over millions of years.
Is there individual variation? Of course.
But, what's generally true for a representative population (e.g. humans who regularly ride bikes) is probably useful as a guide for an individual.
Use non round rings if you want to, our data show they won't hurt your performance.
Cheers,
Jim

So, people with a shorter limb, with muscle imbalances, with arthritic knees, etc. have similar central pattern generators to a group of expert cyclists? This is not what I witness when I ride.

Look I am not refuting the conclussions of your study, I am only saying it has limitations when individuals deviate significantly from the group that was subject to the test. I think that is just plain common sense.

In my case it is not just that I have power data and strava data to back the fact that they work for me. Several people including my coach say my pedalling is much more fluid know. We are talking about a guy that is a five time kona finisher and who trains people that race at ITU level (albeit world cup, not WTS).

And that was measured with metabolic cart, force pedals, and motion capture, or with eyeballs? Gee let me think... You're right, eyeballs are probably just as valid.
If you and the others you mention came to my lab and did trials with round and non-round chainrings I am confident you would see no difference at all. So then we would be right back to saying ride what you like.
Its just a hobby to have fun right? If some part of your equipment makes it more fun then by all means use it.

Jim, Jim, Jim, you missed the key point: he has Strava data. How can you argue with that?

Will never understand why "it won't hurt your performance, so ride it if you like how it feels" isn't good enough for so many folks.

"I like how it feels" isn't exactly unimportant in a leisure activity...

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Tech writer/support on this here site. FIST school instructor and certified bike fitter. Formerly at Diamondback Bikes, LeMond Fitness, FSA, TiCycles, etc.
Coaching and bike fit - http://source-e.net/ Cyclocross blog - https://crosssports.net/ BJJ instruction - https://ballardbjj.com/

I'm only fat because all the training I do has upregulated my chlorophyll expression.

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https://connect.garmin.com/modern/profile/domingjm

My leg length imbalance can be corrected by adding two extra LOOK cleats to one pedal. Tried this for a while and it just did not work. Now just down to a shorter shim. I have thought about different length crank arms as well.

My thought is that the shim makes the effective crank arm length variable throughout the stroke. So for a 170 crank arm with a 5mm shim at 1 o'clock it is 174.35mm and at 2 o'clock it is 172.5mm and back to 170.1mm at 3 o'clock and on down to 165 at 6 o'clock.

Maybe I am wanting to be "the one" but I am thinking that for this instance an oval crank arm would be of help. I know there are some other factors such as femur vs tibia/fibula, ankle flex. I am not so much concerned about power gain but running off the bike like mentioned earlier.

Agreed 100%. I have no scientific or velotron data but converted maybe seven years ago when I was purely a cyclist. I found that at the end of a long hard ride I could still push the big ring hard on the back end of the ride when I fatigued, easier than with round rings. All I could gather was the smaller less dominant muscles that get you through the dead spot fatigue more than your dominant muscles and a oval ring is helping being more reliant on these muscles.

When starting in Ironman and gradually becoming more aggressive with my position I found by playing with the adjustment on my Rotor Q rings I could take some of the load off my lower back as you come over the dead spot and start loading up the leg later with a less closed off hip angle. Essentially you are losing the ability to generate a more powerful pedal stroke but it becomes a trade off over the course of an Ironman letting me be more aero and being able to run off the bike better.

People will ague against oval rings but over the seven years or so I have ridden them everyone who I suggested to try them has become a convert especially since I have started Ironman.

There's a difference between arguing against them and not arguing for them that I think is lost in this thread

So let's see if I follow you witty doctor.

There is this study done with a group of 30 expert cyclists. That concludes that for that group of 30 expert cyclists there is no maximal power gains (nor loss) by using oval chainrings. Then the author makes the wild assumption that this has to work for all mankind, independent of physical traits, age, experience, fitness, etc. hey, but not just for what was tested (maximal power), but also for mean power, fatigue and what not for any duration, terrain and conditions that where not tested.

Yet using a power meter, the observations of a prestigeous coach and bike fitter, and docens of strava runs to determine that in a particular n=1 experiment oval rings do provide better average power and less fatigue is blasphemy.

I guess that is why they classify intelligence in different types. You clearly shine in some aspects and need some help in others.

Well why didn't you mention the prestigious coach and bike fitter before? That completely changes things, at least for me (I won't try to speak for Jim).

It was just below the line you made fun of:

"In my case it is not just that I have power data and strava data to back the fact that they work for me. Several people including my coach say my pedalling is much more fluid know. We are talking about a guy that is a five time kona finisher and who trains people that race at ITU level (albeit world cup, not WTS)."

In this particular study we reported on maximal power. In the second study we measured submaximal efficiency and biomechanics. Those data aren't published yet but you can read the study in the dissertation document.
As I mentioned in another post, feel free to come to my lab and we'll have a look. Your efficiency and your biomechanics may be somewhat unique but the influence of round vs non round chainrings will likely be essentially nonexistent.
You clearly have your mind made up but I feel compelled to make STers aware of our results so that they will be able to make informed decisions.
By the way, its not just our study that shows no influence. Peiffer showed no effect of chainring shape on a 10km time trial. Ratel and colleagues showed no effect on physiological responses. The only studies to show a benefit were a modeling paper with no experimental data and the study by O'Hara who immediately went to work for Rotor after she graduated.
Cheers,
Jim