Bradley Wiggins and Chris Froome both used non-round chainrings on their way to winning the Tour de France. But do they really help?

Five years after Sir Bradley Wiggins became the first Briton to win the Tour de France riding oval rings, Chris Froome continues to use Osymetric chainrings on his Team Sky bike.

Wiggins reverted to round rings towards the end of his career and continued to win at the highest level, including the World Championship time trial. Froome has ridden them since 2011, and has since won three Tour titles using the Osymetric rings.

In addition to Osymetric, Rotor’s Q-rings continue to be used by a considerable number of professional riders. But should you consider using a cam-shaped ring?

Jean-Louis Talo, a mechanical engineer from Menton, France, produced a prototype Osymetric ring and has spent 22 years trying to convince the cycling world that it works.

“You can alter the design so that you give the leg muscles work to do where they are at their strongest and less work to do where they are weak,” says Talo.

“A round chainring gives you work to do where you are weak and takes power away from you where your legs are strongest. A bicycle chainring is round because at one time that’s all factories knew how to produce.”

Great in theory, but does the non-round ring actually work?

Chris Froome rides the Olympic time trial (Watson)

Marginal gains

Tim Kerrison is the performance director at Team Sky, the sports science chief who oversees the training of the team, with particular attention paid to the ‘GC group’.

Kerrison has been instrumental in the successes of Froome, whos has used Osymetric rings on his time trial and road bikes.

Kerrison isn’t a mechanic — bike or bio — but he obviously pays close attention to his riders’ power outputs and equipment. What is his opinion of the rings?

“I’d say that, performance-wise, there is very little in it either way,” said Kerrison. “A few riders have a preference for the Osymetric rings, but many of our riders have tried them. Only a few continue to use them.

“That said, both Wiggins and Froome used them in the 2012 Tour, so they are unlikely to be significantly detrimental to performance.”

The credible tests and research that has been done is inconclusive, according to Kerrison: “Crank-based power measurement systems [e.g. SRM, Quarq] appear to over-report power when using Osymetric rings, which is probably due to the variable angular velocity of the crank throughout the pedal revolution.

“In other words, power reads higher, but this does not correspond with an increase in the power actually being generated by the rider.”

>>> Build your cycling strength with big gear efforts 

Professional cyclists tend to have very efficient pedal strokes, with minimal dead-spots. Perhaps these rings may be more beneficial to the amateur or beginner, helping to iron out a more pronounced dead-spot.

Potential benefits aside, the risk of dropping a chain appears considerably higher, as Sean Yates, the directeur sportif in the 2012 Team Sky car recalls.

“At the Tour, the Sky mechanics were told that dropping the chain was not an option. So they designed a chain guard to make sure that wasn’t going to happen.

“You can drop a chain from round rings too and it’s not really commented on, but with Osymetric it’s a big deal.”

Do they work?

Yes: Dr Mark Pharaoh, Founder of Peekrings, supplier of chainrings for Sarah Storey’s Hour Record attempt bike

Oval chainrings can improve the feel and smoothness of your pedalling action, reduce dead-spots and improve the activation of your glutes and hamstrings.

Set up correctly, you shouldn’t be able to feel the oval. At Peekrings, we use the force curve from a Wattbike test (or some power cranks) to tailor the position of the oval relative to the cranks, so that every oval ring we make is specific to the rider.

No: Paul Barratt, English Institute of Sport on the biomechanical elements for British Cycling

The studies looking into tangible measures of performance are mixed, to say the best.

The claims made for non-round rings is that they delay the onset of muscle fatigue in the quadriceps. The evidence isn’t there to say that it preferentially alters the loading on different muscle groups.

It’s not to say the notion of a non-circular chainring should be dismissed, it’s just there isn’t the evidence out there to support the claims made for them.

Our take

The jury is out regarding the mechanical basis for non-round rings. However, from a psychological point of view, the case in their favour is more compelling. A placebo has the potential to offer a significant performance gain.

That said, the disadvantages of lower-quality shifting and the potential chain drop are significant, especially in a race situation.

  • Samuel Clemens

    Load of bollocks. Mind you, man is infinite in his capacity for self deception.

  • noel crowley

    For over a century engineers have been trying to eliminate the TDC dead spot 60deg. sector where all riders legs are effectively idling but the cleverest pro rider made maximal use of this sector. By making more effective use of the glutes, it’s possible to the same maximal torque at

  • emcel

    As I said, it should be tested using machines and never humans if you want to see if it really improved the power output. It’s very easy actually, connect the crank hand to some kind of motor and have it turned at possible human RPM’s then compare it to the rounded ones result…

    It should be the the power output generated at a set time frame…

  • rikster

    It is hard to imagine that a system as nonlinear as human legs are in translating power into a linear system (round chain ring) do not suffer from inefficiency. Professional legs and training may have narrowed the (in)efficiency curve, but i bet that kids who start training on them will develop differently and get a competitive advantage in the efficiency they obviously provide. I love mine though my legs have developed mostly for running.

  • anthony

    Osymetric chainrings DO WORK! For me at least! I suffered from chronic tendonitis in my knee, and was intrigued by the success of the Osymetric rings. Having fitted a triple set to my previous bike they were an immediate sensation. I no longer suffer from any discomfort, except when I switch back to using conventional round rings. They have been a revelation, in my case. I have since fitted a compact set to my latest bike, and this is where I have come across the major drawback. They are virtually impossible to set up on an 11-speed cassette. Equally, they didn’t have a compatible fit for SRAM cranks at the time. So, I have to fit Rotor cranks, and an Ultegra from mech. I now have them running fine, but they are super sensitive. No doubt this is why Wiggo has discarded them. Remember him throwing his bike at the nationals, due to gear problems? I think that remains the big challenge looking ahead. How to fit these rings with anything more than a 9 speed cassette!

  • Kev

    My memory isn’t good enough to remember that. Thank you for clearing it up.

  • Michael9218

    Ironically, Biopace was based on the opposite theory to current non-round rings in that the Biopace design was meant to slow your movement through the dead zone and speed it up in the power zone. The result was more stress on your knees in the dead zone as the ring was actually larger in radius when you were in the dead zone (12-2 o’clock in the pedal stroke). Current non-round rings are based on an opposite theory to reduce the effective gear ratio in this dead zone and increase the effective gear ratio as your leg straightens (where you have more power available). I’ve been using various designs of non-round rings for several years and can say for me that they do work. More power and less fatigue.

  • Kev

    Shimano come to the conclusion years ago that their Biopace rings didn’t make a difference. They said they did when they made them, stopped making them when they decided they didn’t. or at least that’s what I thought.

  • Gordon

    This style of ring has been out since the late 70’s. Shimano made them. I can’t speak for the science behind the theory , just that it’s not totally a new idea.