Osymetric – Gimmick or Legit?

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At this year’s Tour de France I met an interesting gentleman named Jean-Louis Talo. He was carrying a set of these wacky looking chainrings that I had seen around so I struck up a conversation. I had seen them being used on most of the Team SKY bikes as well as knowing that a few other pros were using them which started to pique my curiosity. As it turns out Jean-Louis is the inventor of Osymetric and he was happy to explain them to me.

The Dead Spot

Jean-Louis Talo is a biomechanical engineer who created the Osymetric chainrings 21 years ago. He understood the theory of “the dead spot” and wanted to improve the efficiency and dynamics of the pedaling cycle. What is this mythical dead spot? The theory states that it is the weakest part of your peal stroke where the crankarms are in the 12 and 6 o’clock positions . Imagine a piston at the very top and bottom of its cycle. There is significantly less power being generated at this transitional point. The shape of the Osymetric rings attempts to concentrate your pedaling power where your force is at a maximum, while effectively reducing the load where your power input is at a minimum. This decreased chainring radius helps you go faster through the dead spot. For example, for a 56T (Osymetric) at the top position (the dead spot) it is not a 56t, it is equivalent to a 52t (easier to think of it being the same diameter as 52t at this position). So, where you are at your weakest, the chainrings are at their smallest to help you go through that quicker. Where you are strong is where the maximum diameter of the chainring is. At the end you have a constant speed of rotation.

Jean-Louis Talo - inventor of Osymetric

Why Are Chainrings Circular Anyway?

Why have chainrings been circular for all these years? According to Jean-Louis, until 1980 the industry was unable to manufacture another shape. Simple as that. It was not a biomechanical decision. As manufacturing techniques progressed and laser cutting became economical, precision shapes were possible to be produced. Jean-Louis’ recognised that the rider has to adapt himself to the circular chainring and he began to experiment with different shapes. Osymetric attempts to adapt its shape to the person.

What about Biopace?

This is the first question that everyone will ask Jean-Louis. As he explains, Biopace was the exact opposite as Osymetric. It was totally wrong from a biomechanical perspective. First of all because it was oval. According to Jean-Louis, a shape needs to be created that is fitted to the pedal stroke – and that shape is not oval. Secondly, Biopace set the crank in line with the large edges of the chainring. With Bio-Pace you actually lost power.

Claimed Benefits

Osymetric claims to produce less lactic acid at your threshold power. On circular chainrings you produce more lactic acid because your vastus externus is employed for too long and being pushed too hard throughout the pedal stroke. Therefore the smaller muscles are used more than your larger muscles could be. With the adapted pedal stroke that Osymetric provides, all the muscles work proportionally to their strength. More muscle fibers are recruited by using the Osymetric shape throughout the pedal stroke which means that each has to work less. This is the theory.

Osymetric claims that you will increase your power 10% with their chainrings. Note that the power is not the speed however. The net result is claimed to be 1% faster and is slightly more efficient when you are climbing than when on the flat. The difference is 0.9 km/hr when climbing, and 0.7km/hr when on the flat.

According to Jean-Louis, he did some testing with Bradley Wiggins during this year. With circular chainrings he tested 450watts at a 20mins average. With Osymetric chainrings Wiggins generated 490watts average (20mins ave). I have not independently verified this, but it’s a point that Jean-Louis is eager to talk about.

My experience

Jean-Louis sent me a set of Osymetric chainrings a couple weeks ago. They came in some ghetto packaging with Ikea-like instructions. Even though these chainrings were just used by the winner and dominating team (SKY) of the Tour de France, I had to remind myself that this is no mass operation. It’s basically a one-man show. The first week I spent countless hours trying to fit them to my Dura-Ace cranks and running back and forth to my bike shop. Installation is not easy and there is no good manual out there that was able to help (Osymetric has this video, but they make it appear easy).

After speaking to the local distributor I was able to follow his advice and get the chainrings fitted. I was still unable to shift into the little chainring properly, so I adjusted the front derailleur so that it stayed on the big ring.

There’s no question that riding these chainrings for the first time feels weird. It’s the exact sensation you’d expect from the shape. However, after 30 minutes of peddling they began to feel perfectly normal. In fact, far better than normal. I couldn’t believe how good I felt while turning over the pedals. I was doing an SE interval up the 1 in 20 (outside of Melbourne) and managed to pull off a time of just over 15mins without even “going for it”. This is far from being scientific, but it wasn’t normal.

The next day I raced our Club Championships with the Osymetric chainrings. It was my first road race in months so all I wanted to do was finish. I felt like I could win it (same old story…I missed the break)

I could be just imagining it but riding these chainrings has felt undeniably awesome. You know those days where you’re pushing a bigger gear than normal and every time you go through a pedal stroke you think, “I can’t believe I’m pushing this”? I have this feeling only a couple times a year when I’ve trained my guts out and been on top form. I have nothing to gain by saying this: I feel like a completely new rider using these chainrings.

What the pros say

It seemed strange to me that if the reported benefits are so great why aren’t all the pros on them. Nobody is sponsored by Osymetric and nobody officially endorses them. In today’s world of multi-million dollar sponsorships, Osymetric stands alone on top of the podium with many victories – including the Tour de France.

I skyped with Richie Porte last night to ask him about what he thinks. Although Richie is able to hold back his enthusiasm towards Osymetric better than I can, he says that he’s definitely a fan. For comparison purposes, he rode Puig Major (a popular climb in Mallorca) on Osymetric rings at an average of 422 watts with a time of 23:59. It was 25watts more than he did this climb previously with normal chainrings. Again, not scientific, but something to consider.

The first professional user of Osymetric was Bobby Julich. Bobby got onto Osymetric by a series of chance events later in his career and won silver in the 2004 Olympic TT (he originally won bronze but Tyler Hamilton was stripped of his gold medal) and many other races in 2005 including Paris-Nice. Of course you don’t just get these chainrings and start winning races, but it’s a great outcome. Bradley Wiggins later got onto Osymetric in 2009 and subsequently finished 4th in the Tour de France. Shortly after Jean-Louis had a good contact within SKY. Now look at the growing list of riders:

Brad Wiggins
David Millar
Richie Porte
Jani Brajkovic
Chris Froome
Chris Sutton
Geraint Thomas
Greg Henderson
Lars Petter Nordhaug (just won Grand Prix Cycliste de Montréal)

I gave Bobby Julich a call last night to get his thoughts and he was generous with his time. He spoke to me for an hour telling me about his past experiences with the Osymetric chainrings. When I asked him what convinced him that these work, he replied, “I was never interested in quantifying with numbers if they did or didn’t work. I heard all the numbers that sounded convincing but at first I just wanted to try them. When I put them on and it was like ice skating – it felt awkward. After half an hour though I thought that they felt so good and natural. Right then I was sold. It had nothing to do with the numbers.”

I also got in touch with Greg Henderson how has used Osymetric for a couple years now. He tells me that he definitely feels like he gets more power out of them, but they’re not as effective for explosive power in the sprints. That said, Hendo has won some pretty big sprints on these chainrings. This is consistent with what I’ve heard from others. The high-end kick seems to be missing.

What the research says

I had wanted to do some of my own testing to try to quantify the savings but after some thought this would take some Vo2 Max equipment, very accurate power meter calibration, lactate samples, and other resources. It’s not as simple as sitting on a stationary trainer and measuring speed at a certain wattage.

It’s difficult to find conclusive research but there are some studies which use mathematical modeling on a variety of elliptical chainrings worth looking at: http://www.noncircularchainring.be/

This study makes some reassuring statements about Osymetric, but it does also state that the orientation of the chainring on the cranks is slightly off (p.25). It also talks about how the rider’s position and geometry of the frame affects the orientation of various chainrings. However, Jean-Louis strongly denies this by saying, “This study was only a mathematical solution. They are not testing this in a physical lab – it is a mathematical model. I love mathematics but this also has to be tested in the physical world. Imagine, where is the dead spot is. It can only be in one place – When your legs are straight up and straight down – just like a piston in an engine. If you move forward or backwards on the saddle, or the geometry of the frame changes, it makes absolutely no difference to the variation of the Osymetric curve.”

Osymetric also have some studies on their website which obviously report significant benefits: http://www.osymetric.com/images/stories/etude.pdf

I’ve heard some sports scientists say that the shape of the chainrings fools the power meter readings into make the measurements appear higher than they really are.Update: I asked an SRM engineer about the possibility of this and he tells me that it would be impossible for the osymetric chainrings to affect the readings of an SRM powermeter. Speaking with other sports scientists, they say that it’s nearly extremely difficult to construct a test that measures the difference between oval chainrings and round chainrings. There are too many variables.

Rotor Q-Rings

I have no experience with the Q-rings and haven’t spoken with anyone from the company about them, but do know a few people who highly rate them. Garmin-Sharp have a sponsorship arrangement with them, however if you look closely you’ll notice that many of the Garmin riders will use the Rotor cranks with circular chainrings, not the oval ones.

The interesting thing about the Rotor crankset is it allows you to position the Q-rings however you want. I asked Jean-Louis about this and he told me that Osymetric is very different from Q-Rings. Jean-Louis believes that in order to eliminate the dead spot you need to create a shape that is biomechanically fitting. He claims that the oval shape does not fit to the legs.

As Jean Louis explains, “Imagine that one of your legs is in the dead spot position. Your strength is divided by 2. You have no strength in this dead spot area. For this reason you have to drastically decrease the radius as part of your chainring to help you go through that dead spot easily and quickly. When your crank is in the strongest position your strength of your legs has been multiplied by 2. For this reason you need a great variation in the radius. If the variation is small you have absolutely no effect”.

“The curve between the high dead spot and the low dead spot is not oval. It’s a creation in function of fitting to the static strength and dynamic strength. For this reason the shape of Osymetric is so particular. Between these two dead spots the radius varies proportionally to your strength. Its fit for each muscle of your legs. In studies, much more fibers in the muscles are working, but each fiber works less. This increases the rider’s lactic threshold is increased. This is important because competition is always decided at lactic threshold. “

You can read more about Rotor’s Q-Rings here: http://www.rotorbikeusa.com/science.html

I don’t have a contact within Rotor so if anybody from the company is reading this feel free to get in touch to better explain the science and benefits.


The Osymetric chainrings are very basic when you look at them. They don’t have the chain catching mechanisms on the inside that enables quick, smooth and reliable shifting like Shimano, Campy or SRAM. They’re basically a thin piece of alloy which have been laser cut in its unique shape.

A look at the inside of the Osymetric chainrings on a Team SKY bike at the Tour de France

As I said before the Osymetric chainrings are very fiddly to install. There are a lot of derailleur and crank arm variations out there and the instructions included with the chainrings are very poor. However, after you understand how to configure the rings to your own bike it becomes much easier. The initial process was painstaking however.

Front shifting is far from being perfect on even the best of set-ups, but dropping the chain is a bit of worry with Osymetric. Careful consideration to which size differences between small and large chainring needs to be addressed. Bobby Julich explained, “The 52T or 42T/54T is a really good combination for flatter races and the 44T/56T is the bomb for time trialing. It’s the magic ring. But you have to be careful when using say a 42T/56T because the difference is so extreme and shifting might not be good”. Also, a brief pause in power while shifting needs to happen. Riders tell me that you’ll sometimes get flicked if you don’t think about your front changes. Time trial bikes seem to be more of a problem than road bikes when shifting. Bradley Wiggins has dropped the chain a fair few times in time trials (e.g. 2012 Tour of Romandie). However, he did use Osymetric throughout every stage of the tour which speaks volumes.

Pros who have experience with Osymetric have found the optimal place to shift. One pro told me, “You don’t want to shift when you’re in the dead spot. That’s when the derailleur has nothing to push against. It’s best to shift when you’re on the power stroke so the derailleur has something to push the chain against. I always had to shift in the beginning of the power phase of the stroke with my right foot (because I’m right footed) and slightly let-off the power. As long as you shift at that right time, it’ll work perfectly”.


Jean-Louis says that it’s effective to go back to training on regular circular chainrings a week before competition and then put the Osymetric back on the day before competition. He calls this the “turbo boost”. I’ve asked around about this and this is what Bradley Wiggins does. However, most of the pros don’t do this because of practical reasons and not wanting to fiddle with the front shifting (most pros only have one training bike, but Wiggo would be well looked after).


People spend thousands of dollars on diminishing gains trying to improve aerodynamics and shed a few grams from their wheels and frames. Meanwhile there appears to be low hanging fruit right in front of us with optimising the dead spot in the pedal stroke. Many will pass this off as some cheap marketing gimmick, but after feeling them for myself I’m completely sold. I imagine if Osymetric had a marketing budget to shape people’s perceptions as much as they’ve shaped their chainrings, we’d all be sold. For the time being, they’ll just have to keep winning the Tour de France.