You’ve most likely heard about oval chainrings. Maybe you even have had the chance to try one but you can’t yet decide if it is worth buying one or not. I will use my experience with oval chainrings to the best of my ability to try and answer all the questions and concerns I’ve seen around. Even some key ones that no one is asking, simply because, in order to even notice these, you need to do some testing with several different types of riders.
If you’re looking for a short answer, I can give you one…
Oval chainrings are effective in climbing and going over technical stuff that requires pedaling. It will somewhat remove the learning curve of proper pedal strokes, which is actually the reason why an oval chainring is not effective for every type of rider.
For riders with smoother pedal strokes, an oval chainring may not be effective at all. They might waste money for a barely noticeable pedal efficiency or none at all.
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Now let’s try to break everything into details and analyze exactly when and where ovals are effective.
How Oval Chainrings Work
The main idea came a long time ago in road cycling. If the chainring is elliptical, you have a different effective number of teeth on each side. Since the number of teeth is what the gear ratio is determined with, effectively, this changes the gear ratio during pedaling strokes.
For example, 32 teeth oval chainring will effectively change between 34 teeth and 30 teeth while rotating. That way, you can have a higher gear ratio in positions where your legs are the strongest and an easier lower gear ratio in a position where you are the weakest.
Those two positions are normally called power phases and recovery phases. Also, there is a thing called the dead spot. It’s a position where one of your legs went down enough to lose power while your other leg didn’t reach the wanted power position yet.
In the long run, your pedaling should be much more efficient. Oval chainring will increase your power to the ground transfer as well.
Will an Oval Chainring Help Me Climb Better?
Yes. Increasing the effective gear ratio when you are the strongest does help with climbing.
While your power phase will benefit only a bit from an oval chainring, your recovery phases and dead spots are where the biggest improvements for climbing happen.
If you think about it, the hardest thing while climbing is that first push of each pedal stroke. It proceeds right after the recovery phase, which completely interrupts the flow. By making recovery phases easier, you are able to pedal more smoothly and that is the key to an easy climb.
Not only it’s easier for your legs, but it increases traction a lot. Traction is lost when a burst of power/spin force happens. Your tires can’t transfer that instant power to the ground. If the power delivery is evenly distributed, it’s much harder for tires to lose traction.
So, to sum this up, oval chainrings increase traction and give you the ability to smoothen out your pedaling strokes, which greatly increases climbing ability.
Ovals vs. Technical Stuff
It’s obvious to realize that chainring changes, in general, won’t make a better rider out of you. Especially in terms of technical stuff on trails.
However, what an oval chainring might help you with is avoiding those dead spots when you want to hop onto something, and you make a mistake. You will keep at least some power to recover from an epic fail and keep going. It all depends on the way you make a mistake but from my experience, it helped me save myself from falls a decent number of times.
And we all know how costly those falls can be.
Why There Are So Many People Experiencing No Benefits With Oval Chainrings
If you take some time to read forum topics on oval chainrings, you will see kind of conflicted opinions about them. Usually, it’s a 50/50 ratio of people who claim amazing benefits and those who didn’t experience any difference.
Since I’m not writing these articles to be sales pitches but rather to try and help people better understand mountain biking technology, I will explain why this is the case.
It’s quite hard to find some decent explanation on the internet about this. Everyone is just telling you to buy and try them. So, naturally, when I wanted to try one, I had no other option but to open my wallet.
Since then, I’ve seen several Youtube mountain bikers come to the same conclusions as me and my group of friends. We each took some time testing it and shared our opinions in the end. We made it into sort of a study on different types of riders. Which, in the end, turned out to be the key element to figuring it out.
Different Pedaling Strokes
The number one thing we all agreed upon was that it mostly depends on how smooth your pedaling is. People who climbed the most developed the smoothest pedaling technique. They naturally had no dead spots and their recovery phases were not about recovery at all. They are just a bit less powerful than their power phases.
They had no benefit from any kind of chainring different than the standard round ones.
On the other hand, people who had a stroke heavy pedaling with quick bursts of power during power phases experienced huge improvements in pedaling smoothness. Especially on climbs, they had much less wheel spin, which results in loss of power and inertia, but instead, they kept more speed between pedaling cycles.
We quickly made a connection between leg strength and smooth pedaling. At first, it seems counter-intuitive, but really it isn’t.
Stronger riders, in general, did not have stronger power phases. However, their recovery phases were much shorter or barely existent.
So, that is the second rider feature that partially excluded the benefits of oval chainrings. Partially, because no matter how strong your legs are, you can’t counter the mechanical benefit of different teeth number on oval chainrings.
A bit weaker riders, however, had lots of improvements with oval chainrings.
Flat pedals are harder to climb and keep good traction. Mainly because your feet are not fixed on them as they would be on clipless pedals. It affects the smoothness of pedaling and power transfer from your legs to the drivetrain.
All of us tested oval chainrings with flat and clipless pedals. Literally, everyone improved on their climbs while using flat pedals, no matter how smooth their pedaling technique was before.
Frequent Questions I’ve Found on Forums
I’ve seen a lot of people asking or claiming oval chainrings helped them with knee pain.
Now, I’m not an expert on injuries and all of that, but I took some time searching the internet for a possible explanation.
My understanding is that the knee is one of the joints that sustains continuous pressure from physical activity quite well. However, frequent changes in pressure intensity, not so much. Probably, the reduced power change between the recovery phase and power phase has something to do with less stress on our knees.
That’s the only outcome that I could find a medical explanation for, but don’t take this for granted, I might be wrong.
Less common, but a valid question nonetheless, was about the necessary chain length with ovals.
The answer here is simple, yet it might be complicated if your chain wasn’t in proper length in the first place.
If your chain is from a factory, you won’t have any problems because, with an equal number of teeth, round or oval chainring won’t make any difference. However, if you changed your chain and it was just a bit shorter than it should have been, then you might experience problems on the biggest cassette cog. This will happen because the derailleur will be stretched to the maximum, and effective teeth difference on ovals still causes a bit of a pull on the derailleur.
So, all you need to make sure is that your derailleur still has some room forward when the chain is in the biggest cassette cog.
Some oval users experienced their clutch mechanism wearing out. I will immediately mention that I’ve found this happening only on some Shimano clutch derailleurs and certainly not on 2019 ones.
The way that ovals pull on the chain causes constant tension on the clutch. The reason this happened with Shimano and not any other major derailleur brand is because their clutches were a lot stiffer. Riders that used, for example, both Sram and Shimano clutch derailleurs will know that Sram’s clutch is not as stiff as Shimano’s while achieving the same effect.
Obviously, increased tension of stiff clutch causes more wear and otherwise unnecessary maintenance.
This might be the only drawback of an oval chainring that I’ve ever found or experienced.
Not every chain guide will fit with oval chainrings so many people asked for specific oval chain guides.
My first choice would be to check if the same manufacturer, that makes your oval chainring, makes an adequate chain guide for it as well. If not, then check which chain guide covers at least +2/-2 for the number of teeth your chainring has.
Make sure that the one you are getting has a mount that fits your frame or bottom bracket.
Should I Buy an Oval Chainring?
If you have an uneven pedaling and it’s affecting your climbs, then it might be a good idea to consider buying one.
I’m the person that did not benefit from an oval that much, but I would still try one out for myself simply because I’m an enthusiast wishing to test and know everything there is about mountain biking.
There are three brands that I would recommend, absoluteBLACK, OneUp, and Wolf Tooth. Mainly because they offer pretty much the same perfectly designed product in a comparable price range.
Some other brands make these, which I can’t recommend because of their questionable quality and lack of some important features such as narrow-wide teeth.
There is also less known SRAM’s X-SYNC Oval chainring which is amazing, maybe even the best of all because of their market-leading teeth design, but I don’t feel like their high price point is justified.
What’s more important than choosing which one of these you want is buying the chainring that fits your crankset mount. Each crankset manufacturer has a different mount, while Shimano has different mounts for almost each of their groupsets. Luckily, all of the brands mentioned above sell different versions of the same chainring compatible with all the market-leading crankset manufacturers.
Choosing the number of teeth should be pretty straightforward. If you are happy with the number of teeth on your current setup, then choose the same for the oval.