Osymetric chainrings: do they work?
Bradley Wiggins leading the 2012 Tour de France
You can't help but have noticed those ‘weird' chainrings on some pro riders' bikes in the past couple of years.
They've been most prominent on the Team Sky Pinarellos of Bradley Wiggins and Chris Froome, though other teams' riders have also fitted them. You'll struggle to see a sticker or a brand name on them, though, because the riders in question are not sponsored to use these oddly-shaped items.
In fact, although Team Sky is sponsored by Shimano to use its groupsets, Wiggins chose to use French-designed and made Osymetric chainrings on both his road and time trial bike during his stellar 2012 season.
How did the two Sky superstars end up with these chainrings on their bikes? Was it the outcome of Team Sky's famous ‘marginal gains' research? Or was it another quirk from the sideburned one?
Actually, former Sky coach Bobby Julich was the first pro rider who used the strange double cam, squashed-profile rings, though when he arrived at Sky as a coach in 2011, riders were already using them.
"Yeah, I was the first guy to use them, back in 2003, and then I used them for the rest of my career," recalls Julich, now a freelance coach based in Nice. Julich was riding for CSC at the time and looking for every natural advantage he could find.
"By chance I met a trainer one day in Nice and we got talking and he said, ‘Oh, there's a guy, a friend of mine in Menton and he has the product of the century! It's an oval chainring!' and I was like, ‘Oh my God - Biopace,' so I kind of blew it off for a month, but one day I called Jean-Louis [Talo] and I immediately started using them.
Early reliability issues have been solved
Doing the rounds
"With Bjarne [Riis] at CSC, it was very difficult to get him to agree to me using them, but he allowed me to use the small ring because it was hidden behind the big ring. But I went to the Athens Games and I said, ‘Listen, I'm putting both rings on my bike, I'm not here with CSC, I'm here with the national team and I can use whatever I want.' And I never took them off my bike after that."
Function, not frills
Julich's medal-winning use of the Osymetric rings raised their profile, but the lack of marketing budget means that Osymetric cannot afford to pay teams to use its product. "Jean-Louis gave out a lot of rings, some guys liked them and some didn't, but the bottom line was it was very difficult for a lot of teams to allow you to use them.
"When I came to Team Sky, I was pretty amazed that so many guys were using the rings, but obviously when you are sponsoring a team for 500 groupsets per year, it's very difficult to get your star riders to use the competition or something you don't make."
However, in spite of the reluctance of team management and the inherent conservatism of riders and coaches, the elliptical chainring refuses to go away. "The guys that use them have them on all their bikes, road bikes as well. Obviously Sky had a lot of guys who had them on both road and TT bikes, not just TT. The time trial is very important and I think the rings are super for that sort of effort, but they are better for the longer races.
"I'd say that the harder the race, the better the effect the rings actually have, spreading out the workload over more muscle fibres, getting you over the dead spot quicker so you are in the power stroke more. I actually think it's even more important to use them when you are climbing than when you are riding a time trial," says Julich, who has them on his road bike to this day.
Potential gains remain unproven
Regarding the weirdness of their shape, Julich insists that the re-education period, where you have to learn how to pedal them, doesn't take long. "It's not like riding those old Biopace rings when it felt like you were bouncing down the road, though there is definitely an adjustment phase because you are pushing a different shape around every time you pedal.
"I would say that after 20-30 minutes of your first ride, you don't feel it at all. Maybe it'll take two or three more rides to adapt to them 100 per cent. I remember, when I first used them in Europe, guys were coming up to me and saying, ‘Wow, I expected to see you bouncing down the road trying to pedal them, but it just looked normal!' And I said, ‘Well, of course it was.'"
Osymetric is a small company with limited resources, so there is no mechanically compatible chainset or front derailleur. At the 2012 Tour of Romandy, Wiggins's chain unshipped when he shifted from big to small ring in the final, race-deciding time trial. Even so, it didn't put him off using them, and Sky's mechanics were put on the case. It was a potentially serious problem, as Sean Yates, the directeur sportif in the Team Sky car and Wiggins's confidante throughout 2012, recalls.
"At the Tour, the Sky mechanics were told that dropping the chain was not an option, just not an option," Yates says. "So they designed a chainguard to make sure that wasn't going to happen. The thing is that you can drop a chain from round rings too, and it's not really commented on, but with Osymetric it's a big deal."
The benefit for time trial is arguably quite small
The other thing that's slightly problematic is the fact that there are no chamfers or pins to help shift the chain between small and big ring on the Osymetric rings. This puts a much greater strain on the front mech to mechanically push the chain up and over - without any assistance from the inner face of the big ring.
"If the rings were manufactured with those additional elements, the price would go up again, and that's not really an option for Jean-Louis," notes Jon Sharples of TrainSharp, the UK importer of Osymetric rings and Yates's partner in their coaching company.
In a quest for low weight, the Shimano Dura-Ace front mech cage has been shaved away to wafer-thin dimensions and has too much flex to force the chain up without the aid of ramps on the chainring, so mechanics have taken to fitting the more robust Ultegra front mech when Osymetric rings are fitted.
Bespoke chaingaurd prevents unshipping
The last word here should surely go to Julich, the rider who introduced these rings to the sport and who won Paris-Nice, Critérium International and the Tour of Benelux in 2005 on them. "I never put any pressure on any of these guys to use them when I was at Sky. They really felt beneficial to me, and if the guys asked what they were like, I'd say try them and if you like them use them," he explains.
"If you believe that crossing yourself before a race is going to allow you to have a stronger race, then do it, or if you think that eating a protein bar right after the race is going to help you, then do that. A lot of people expect a different answer from me... but I'm just telling you how I see it."
So, do they work? From a purely physiological point of view, the answer is a resounding maybe. But from a psychological point of view, the answer would appear to be a far more convincing yes. And, just throwing this out there, two of the riders who have enjoyed most success on the Osymetric rings - Wiggins and Froome - are tall riders with long legs. Might it be that that those with long levers feel the most benefit?
Team Sky Performance director Tim Kerrison's view
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 is instrumental in training Bradley Wiggins and Chris Froome, both of whom used Osymetric rings on their 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 was his opinion on the rings?
"I'd say that, performance-wise, there is very little in it either way. A few riders have a preference for the Osymetric rings, but many of our riders have tried them, and only a few continue to use them. That said, both Wiggins and Froome used them in last year's Tour, so they are unlikely to be significantly detrimental to performance," says Kerrison.
Credible tests and research have been inconclusive, according to Kerrison and others. "Crank-based power measurement systems (such as SRM) 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, or the resultant speed/performance."
Regardless of the power data, Kerrison and the others know that if a rider believes those cranks help him race better or stronger, it would be unwise to dissuade him. The psychological effect in performance is not negligible in this regard. So, though he is sceptical, Kerrison isn't calling the rings voodoo.
"For riders who prefer to race on the Osymetric rings, I always advocate doing significant training blocks on normal rings. For example, Bradley did all his training from November 2011 until May 2012 on normal chainrings. And he is back training on normal rings now [March 2013]."
Closely linked as Team Sky and British Cycling have been, the BC boffins obviously took a look at the chainrings - along with everything down to the aero effect of different stitching designs on skinsuits - prior to the London Olympics. Wiggins won gold at the time trial, with Froome in bronze, both using Osymetric chainrings, and both used Osymetric rings on their road bikes in the road race too.
Wiggo en route to Olympic gold
Paul Barratt, who works for the English Institute of Sport on the biomechanics elements for BC, did some investigation about the supposed benefits and, like others, reckons that the evidence is inconclusive. "In my opinion, the studies looking into tangible measures of performance are mixed at best," he says.
"The claims made for them, that they delay the onset of muscle fatigue in the quadriceps... Well, 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 so often made about them."
Barratt, as open-minded as any good scientist, adds, "I wouldn't dismiss the idea, it's just I'd rather base a decision on data rather than a concept [‘reducing the deadspot']. It's great that there is evidence to show changes in coordination [neurological adaptation] but the key question remains: do these changes translate into a performance improvement or reduction in injury?"
This article was first published in the April 04 issue of Cycling Weekly. Read Cycling Weekly magazine on the day of release where ever you are in the world International digital edition, UK digital edition. And if you like us, rate us!