By Robbie Broughton
Oval chainrings have drawn a fair amount of scepticism over the years. But then Bradley Wiggins won the 2012 Tour de France using them, and Chris Froome also has them on the Team Sky bike that has seen him, with the help of an inhaler or not, win five grand tours. What claims do the manufacturers make, and is it worth you making the change?
Unless you’re a seasoned professional bike rider, the chances are that you don’t have a very even pedal stroke when using a standard ‘round’ chainring. Your maximum power in your pedal stroke comes when your pedals are at a quarter to three position. When you get past that, you will have less power – when your pedals are at the six O’Clock position you will enter a ‘dead spot’ where you are generating less power, until the pedals return to a quarter to three position again. This means that many of us don’t have a very consistent stroke.
Because of its shape the oval chainring is larger in the power phase of your stroke and smaller when not in the power phase. In this way it’s making the most of the most powerful part of your pedal stroke, and then minimising the amount of resistance at your weakest, thus eliminating that ‘dead spot.’
The theory is that an oval chainring will therefore enhance a cyclist’s ability to spin with a smoother power delivery, helping the rider to generate and maintain a more constant cadence. Ironically, your pedal stroke will be more ‘round’ with an oval than a round chainring and will increase your average speed.
It should also make climbing steep hills a little easier as well as reducing peak loads on knee joints, allowing the rider to keep up their level of effort for longer.
Furthermore, manufacturers claim that the effort used when pedalling an oval chainring uses more muscle groups – but each of them to a lesser degree. The overall load of pedalling is spread over a greater muscle mass. So this results in fresher and more relaxed legs, and higher average speed uphill. Spreading the load over more muscles also reduces the risk of cramp.
Rather annoyingly, it’s difficult to find really good scientific reports that irrefutably back up these claims – much of the evidence is anecdotal. However most reviews acknowledge that, after an initial awkward adjustment for the first 30 minutes or so, the pedal stroke soon feels natural and there is a perceived slight improvement in keeping a consistent cadence and possible efficiency. Some have suggested that these improvements could merely be a placebo effect!
It’s curious that there aren’t more professional cyclists taking advantage of these marginal gains. Not all of the Team Sky contingent use them, with some riders stating a strong preference for the traditional round ring. Could it be that the super efficient pedal strokes that they’ve developed cancel out the benefits of an oval ring? If so, that would still mean that us amateurs could be getting some good out of them – those Strava PBs may well be smashed!
There is another good reason for making the change. When AbsoluteBLACK, a company that had been servicing the needs of the mountain bike community for some years, turned its attention to us roadies, they launched a new range of oval rings in 2016. Not only did they make the same claims about pedal efficiency, they completely reset the bar in what the plain old chain ring should look like with stunning and intricate machining.
They come in black, racing red, grey and, get this…’champagne.’
These are not mere parts of a bike that help make a chain turn your wheel efficiently. They’re more than that. These are works of art, objects of beauty and desire. In the same way that Campagnolo reached that zenith of engineering and aesthetic beauty rolled into one, AbsoluteBLACK’s designs set the heart racing.
The problem with all that elaborate detailing on them is that they can pick up an awful lot of dirt on winter rides and so they’ve now launched a range of oval winter chainrings with a smoother surface with fewer nooks and crannies for the road dirt and grime to get in them. That makes them great for a winter training bike or, if you’re into that sort of thing, gravel riding. Check out the video.
So the next time you’re building up a bike from scratch or thinking about changing your chainring, it’s worth giving ovals a try. AbsoluteBLACK offer a 30 day trial saying that if you’re not “delighted” with your purchase, they’ll exchange it for a round one, free of charge.
If you’ve tried an oval chainring let us know your thoughts!