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Mountain bikers and cyclists are an opinionated bunch. We know what we like and if you’re not on board then you’re wrong. Whether it’s debating flat pedals vs clipless, Shimano or SRAM, chamois or no chamois, the list goes on and on.
One debate that has waxed and waned over the decades is whether oval chainrings help or hinder a rider’s performance and overall experience on two wheels.
Personally, I love my absoluteBLACK oval chainring. All of my mountain bikes have had one for the past several years and I don’t see myself going back to a round ring.
In this post, I share my thoughts on oval chainrings, their pros and cons, who benefits the most from them, and more. If you’ve been curious about trying an oval chainring, read on to see if it’s a good fit!
What are oval chainrings?
Oval chainrings are… oval chainrings. They’re shaped like an ellipse rather than a standard circle.
Oval chainrings are meant to be installed on the cranks as the front chainring. They can be used as a single 1x ring (typically for modern-day mountain bikes) or as part of a 2x or 3x chainring set with a front derailleur.
How do they work?
“Oval chainrings maximize the part of the stroke where power is produced and minimize resistance where it isn’t” – absoluteBLACK
Essentially, oval chainrings change the gear ratio of your drivetrain as you pedal without needing to shift.
Let’s break this down.
Gear ratio is basically the ratio between the number of gears on one wheel/ring in relation to the number of gears on a second wheel/ring.
With a normal circular chainring, the gear ratio doesn’t change because both the front chainring and the chainring on the rear cassette are perfect circles. (The gear ratio changes when you shift gears, but not when you stay in one gear).
This result is a perfectly circular pedal rotation.
Now let’s add an oval front chainring. As you can see in the animation below, the oval shape of the front chainring effectively changes the gearing as you pedal in the same gear.
So, if you have a 34 T (T = tooth) oval chainring, it acts like a 36 T (harder gear) during the power phase of your pedal stroke to deliver maximum force.
Conversely, when your pedal stroke is in the recovery zone, the oval chainring acts like a 32 T (easier gear) chainring to allow for rest.
Having an ellipse-shaped chainring, therefore, gives you more power in the ‘punch’ stroke of your pedal, which can help with acceleration and getting up short, steep climbs.
On the flip side, an ellipse-shaped chainring makes it easier to pedal in the recovery zone because the gear ratio drops.
What are the benefits?
There are a lot of benefits to running an oval chainring on your bike. There are always going to be the haters that say it’s all BS, but I personally love mine and I feel like it definitely delivers on each of these points:
- Improved efficiency when climbing: because an oval maximizes the power stroke and reduces the dead zone during pedaling, it can really improve efficiency when climbing hills. An oval chainring becomes even more helpful on short, steep, punchy climbs that require intense bouts of power.
- Less fatigue: Better efficiency when pedaling results in less fatigue over time. Studies have actually shown that an oval chainring “consumes less energy at the same power output”.
- Smoother delivery of power to the rear wheel: This is because oval chainrings work with the natural power output of your pedal stroke by maximizing force and then easing back for recovery. This rhythm provides a smoother delivery of power to your rear wheel. Round chainrings, on the other hand, have a more pronounced dead zone, which results in a pulsating delivery of power to the rear wheel.
- Better traction: Since there is a smoother transfer of power to the rear wheel, mountain bikers will notice much better traction thanks to a consistent pedaling cadence with no pronounced dead zone.
- Shift less: Riders using an oval chainring will also notice that they need to shift less. This is because ovals provide the benefit of a changing gear ratio throughout their pedal stroke.
- More torque & no dead zone: For slow-speed tech where you need to maintain constant torque for balance and power, an oval chainring definitely excels.
- Faster acceleration: Oval chainrings maximize the power stroke, so riders will experience faster acceleration compared to a round chainring
What are the drawbacks?
Of course, there are some drawbacks to running an oval chainring:
- Not great for pedaling at high RPMS: The biggest drawback to an oval chainring is that riders who really like to push will probably notice they can’t get consistent power when pedaling hard. This is because the oval chainring acts like a smaller (easier) chainring during the recovery phase. If you’re a racer or hard-charger, an oval chainring might not be for you.
- Extra cost: Purchasing an oval chainring will be an extra cost to your already expensive bike that already has a perfectly fine chainring.
- Some riders might not like the feel: Lastly, an oval chainring does feel different than a round chainring and some riders might not like or even get used to that feeling.
Pros and cons at a glance
Oval chainrings for mountain bikers
Oval chainrings really shine for mountain bikers who do a lot of technical riding. Because they improve power, torque, and traction, I notice a huge difference when tackling slow-speed tech like rock gardens and punchy climbs. Having that extra oomf in the power phase can mean the difference between getting up and over an obstacle and not.
For riders who do mostly cross-country riding, ovals can still make a difference as long as you’re not looking to hammer out mile after mile. Ovals are designed to improve efficiency and reduce fatigue, but as I mentioned above, they aren’t great for pedaling for long distances at high RPMs.
On the flip side, oval chainrings aren’t a great option for riders really looking to lay down the watts. My brother is an aggressive and powerful mountain biker and he didn’t like his oval chainring because he felt like he ran out of gears when charging hard. This is because his 34T oval chainring acted like a 32T (easier) gear for half of his pedal stroke rather than working as a constant 34T chainring.
Oval chainrings for road/gravel cyclists
I have less experience using an oval chainring on road and gravel bikes, but they can be used on 2x or even 3x bikes (bikes with a front derailleur and 2 or 3 chainrings).
Since roadies and gravel riders tend to pedal at higher RPMs than mountain bikers, though, oval chainrings aren’t quite as common.
That being said, some road and gravel riders choose to add an oval chainring as one or both of their front chainrings to help smooth out pedaling cadence and make hills just a little bit easier.
Oval chainrings & knee pain
One of the biggest arguments against oval chainrings is that they cause knee pain. Conversely, one of the biggest reason to get an oval chainring is that the reduce knee pain when biking.
As a long-time user of an oval chainring myself, I have not experienced any knee pain when mountain biking (I can’t speak to oval rings on road or gravel bikes).
Knee pain can be caused by a lot of different things, most notably poor bike fit. There’s no evidence that an oval chainring causes knee pain.
Buying an Oval chainring
Convinced? I hope so because I think oval chainrings are awesome (for mountain bikers, at least!)
But before you buy one, there are a few things you need to consider:
- Tooth size
- Drivetrain make
Just like a round chainring, you’ll need to decide what tooth size oval chainring you want. The key thing to remember, though, is that whatever tooth size you choose, it will really be 2+ and 2- that gearing due to the change in gear ratio when pedaling with an oval chainring.
For example, if you choose a 30T oval chainring, you’re really getting a 28T and a 32T. The 28T is when the chainring is in the recovery position and the 32T is when you’re in the power position.
Oval chainrings typically come in 30T, 32T, and 34T options for mountain bikers and up to 50T for the outer ring on road/gravel bikes.
- Smaller rings mean lower (easier) gear which is great if you live in a hilly or mountainous area.
- Bigger rings mean higher (harder) gears, which gives you more power.
Personally, I have a 30T oval chainring, which gives me 28T for steep hills and 32T for charging hard.
Drivetrain groupset make
The second thing you want to consider is the make of your drivetrain groupset. Oval chainrings fit onto the cranks of your bike and different groupset manufacturers require a different fit.
SRAM and Shimano are the two biggest makers of groupset, but you may also have Race Face, Cannondale, or another brand. Make sure you get an oval chainring that matches the manufacturer of your groupset.
absoluteBLACK is my choice for oval chainrings. They’re really the leader in the field when it comes to availability, color choice, research, and development.
I’ve used absoluteBLACK oval chainrings for years and they’ve never failed me!
You can shop for your own at:
How to install an oval chainring
You can take your shiny new oval chainring to your LBS (local bike shop) and have them install it for you, or, if you have the tools, you can do it yourself.
The biggest thing you need to pay attention to is the position of the oval chainring. On absoluteBLACK rings, there is a little dot that needs to line up with the center of the cranks. This ensures that the power and recovery phases are in the position they need to be when pedaling.
Here are a few videos that might help if you choose to do your own installation:
- Fitting a direct mount MTB chainring (this isn’t oval-specific but it’s the same process. Just make sure the dot is lined up vertically with your cranks)
- An oval installation by Mitch On Two Wheels
- Installing an absoluteBLACK oval road chainring
Final thoughts on oval chainrings
I have ridden with an absoluteBLACK oval chainring on my mountain bikes for 6 years and I’ll continue to ride with one on my future bikes.
I definitely think they make a big difference when it comes to riding slow-speed technical trails, improving traction, and making tough climbs just a tad bit easier.
They are an extra cost to your already expensive bike, but personally, I think it’s worth it.
I’m also excited to try out oval chainrings as I get more into gravel biking!
- Flat vs Clipless Pedals: Which are better for mountain biking?
- Mountain Bike Essentials: Beginner recommendations
- 6 Things I Wish I Had Known Before Taking Mountain Biking Seriously
Do you ride with an oval chainring? What are your thoughts? Did you try one and not like it? What questions do you still have? Leave a comment below!