Chainrings are integral to powering your bike.
They transmit the power you create by turning the pedals and cranks to the rear wheel via the chain. They also optimize your pedal power by utilizing different gear ratios for different terrains and gradients. They’re conventionally circular – but oval chainrings are becoming more and more popular.
But what is an oval chainring? And why do some riders prefer them to a round chainring?
To give you the lowdown on all there is to know about oval chainrings, we’ll be covering:
- What Are Oval Chainrings?
- How Do They Work?
- The Pros and Cons of Oval Chainrings
- Are Oval Chainrings Better Than Round Chainrings?
Ready to ramp up your oval chainring knowledge?
Let’s get stuck in!
What Are Oval Chainrings?
For decades, the simple round chainring was unquestioned as the standard component that transferred crank force to your drivetrain.
But as cycling evolved alongside technology, engineers and manufacturers began rethinking the round chainring and how it could be optimized for performance gains.
Oval chainrings – also known as “elliptical chainrings” are designed to help to maximize the power of your pedal stroke at its peak. This helps to make pedaling easier when you’re in the non-optimal part of your pedal stroke.
Essentially, oval chainrings minimize the amount of force you exert on the “dead spot” of the chainring. The concept is that oval chainrings maximize the part of the stroke where power is produced and minimize resistance where it isn’t.
How Do They Work?
As a result of the oval shape, the radius of the chainring increases as you pedal your bike.
When the pedals are vertical, the radius is reduced on the part of the chainring the chain is in contact with, simulating a smaller chainring. This reduces resistance for the part of the pedal stroke at which it is naturally weakest.
Conversely, when the pedals are horizontal, the radius is increased on the part of the chainring the chain is in contact with, simulating a larger chainring. This increases resistance (and therefore power) for the part of the pedal stroke at which it is naturally strongest.
Just to be clear – oval chainrings don’t automatically produce more speed. Instead, they are designed to increase pedaling efficiency.
The Pros and Cons Of Oval Chainrings
#1. Power Consistency
First and foremost, increased power consistency is a huge advantage of oval chainrings.
Since oval chainrings help to smooth out your pedal stroke and minimize the dead spot in the pedal stroke, cyclists can exert force with more consistency. This is pivotal, especially for steep climbs, as oval chainrings make it easier to use a higher gear with a slower pedaling cadence.
Oval rings are excellent for improving rear tire traction, especially on loose, slippery terrain.
This is a huge win for mountain and gravel riders, as riders can take advantage of improved cycling cadences and maintain a consistent pedaling speed for longer. Thanks to oval MTB chainrings, the chance of slipping or spinning the rear wheel while climbing is reduced.
Oval chainrings are the bee’s knees for ergonomics.
This is because there’s less disruption to the flow and cadence of your pedaling, meaning you don’t have to overwork your knees in the more rigorous parts of pedaling.
Also, oval chainrings improve the activation of your glutes and hamstrings. This enables you to engage the stronger parts of your legs while taking some of the strain off from your knees.
This is because on round chainrings, your vastus lateralis (the largest part of your quad muscles) is engaged for too long and therefore worked too hard throughout the pedal stroke.
With the oval chainring, the leg muscles do the most work when they’re naturally at their strongest – and less work where they’re weak.
Many oval chainring models offer different configurations to be adapted to your pedaling style and specific needs.
Oval chainrings can be used to improve pedaling on a wide range of bike styles, including mountain bikes, hybrid bikes, tri-bikes, and even single-speeds – though we’ll be looking at that in a little more depth.
Perhaps this one goes without saying, but oval chainrings might take some adjusting to.
This might mean adjusting the configuration or even changing your technique for better comfort and power. Rest assured, oval chainrings will feel as natural as round chainrings after a few weeks.
For every bike part, the cost will always be a factor.
Since it’s likely your standard round chainring is included in the initial price of your bike, the upgrade to an oval chainring will cost you.
#3. Single-Speed Bikes
If you’re a single-speed bike rider and are desperate for an oval chainring, you might run into some problems.
With the oval shape pointing forward, the chain is stretched more which results in extra chain slack after the crank rotates past the peak of the oval shape.
As single-speed bikes don’t have a derailleur to gobble up the chain slack, there are a few technical adjustments to be made. An oval chainring with the right shape and a narrow-wide teeth pattern will enable maximum chain retention and make any differences in pedaling almost unnoticeable.
Also, some cyclists argue that the chain drop is noticeably higher for oval chainrings – which presents its own set of problems, not just for single-speed riders.
#4. Knee Pain
Obviously, this depends on the rider and their knees.
Some riders love oval chainrings and find them more comfortable on their knees than round chainrings. On the other hand, some cyclists hate oval chainrings because they’ve caused them knee problems.
Are Oval Chainrings Better Than Round Rings?
The question we’ve all been waiting for…
Oval chainrings can be fairly controversial within the cycling community. Either you love them or you hate them.
Scientific studies have been carried out to find out the comparison in performance. One study found up to a 9% increase in force effectiveness, up to 7% less oxygen consumption, and up to 10% heat rate decrease when using oval chainrings over round chainrings.
That’s not to say there’s no place for circular chainrings. There’s a simple logic to the round chainring as well: they’re predictable and provide a consistent amount of resistance when pedaling. Some cyclists will always simply prefer a round chainring.
However, the biomechanics of the pedal stroke mean the rider doesn’t apply pressure to the cranks in an exact linear motion.
In any crank rotation involving human biomechanics, there will be weak spots. Although these weak spots are marginal for professional cyclists with a refined pedal technique, a round chainring can exacerbate the weak spots in your pedal stroke.
And while most of the peloton still use conventional round chainrings, more and more of the sport’s biggest names have been converted to the oval chainring in recent years.
Chris Froome and Bradley Wiggins both opted for elliptical chainrings during their Tour de France victories – so they’re hardly seen as a wacky bit of kit for the cycling eccentric these days!
If oval chainrings are good enough for those two, they’re probably good enough for us too!