Going In Circles From Ovals To Rectangles

When I heard that Chris Froome won this year's Tour de France with an elliptical chainring, I thought of the immortal words of Yogi Berra, "It's deja vu all over again!"

There was something of a minor fad for them when I first became a dedicated cyclist, in the mid-1970s.  At that point, I think there were so few experienced cyclists (at least here in the US) that people were willing to try just about anything.  Sometimes that worked for the better, as with the case of SunTour derailleurs.  (I don't know anyone who went back to Simplex or Huret derailleurs after trying SunTour.)  In other cases, the new product didn't work well or, as in the case of elliptical chainrings, most riders didn't notice any difference.



Durham "Camel" chainring, circa 1975. Photo by Chuck Kichline.

Interestingly, oval-shaped rings enjoyed something of a renaissance a decade later, when Shimano resurrected the idea in its Biopace chainrings. It shape wasn't as exaggerated as that of the "Camel" ring in the above photo, but it looked noticeably different from round rings. It seemed that most people who rode them were in the then-emerging field of mountain or off-road riding.  Shimano offered Biopace road rings, but they weren't nearly as popular as the mountain versions.  The reason for that is, I believe, that mountain riding, being a relatively new sport, had younger riders who weren't as fixed in their habits as the older road cyclists and cyclotourists--who seemed to be a dying breed, at least here in the US, by the late 1980s.   Also, as someone explained to me at one of the trade shows, mountain riders tended to rely more on raw power than road cyclists, who prized a smooth, symmetrical stroke more. 

Shimano Biopace --loved and hated by more cyclists (who may or may not have used them)  than, possibly, any other chainring-- on 1985 Ritchey Annapurna.  From Mombat.org

Whether that person's theory holds any water, I'll never know.  I have never used any chainring that wasn't round--except for a couple of times when I fell or crashed and turned my chainring into a taco or a crepe, depending on whether I was on my Dakota or my Motobecane.  Let me tell you, neither of those shapes does much for your pedaling efficiency!

Given this history, I was skeptical when I heard that Froome rode an oval chainring.  I didn't doubt that he rode it:  Riders on professional teams usually ride whatever their sponsors give them, and I suspected that whoever made the ring kicked some money into Team SKY.  That suspicion turned out to be correct, though the identity of the sponsor--and his product--were not quite what I expected.

Turns out, Jean-Louis Talo invented the Osymetric rings Froome and some of his teammates were riding.  The mechanical engineer, who hails from Menton (right next to the Italian border), developed his design in 1993 and has been trying to convince riders and teams to use it ever since.  Bradley Wiggins won the 2012 Tour with an Osymetric ring, and Froome won the following year's Tour with an "O".  After that, orders flooded into Talo's Nice-based Biosquat S.R.L., especially from the UK (no surprise, as Wiggins and Froome are British) and China. 

Chris Froome's bike. 

Now, some of those orders surely came from folks who had more money than cycling skill and want to ride whatever Tour winners ride. But others no doubt came from racers who are looking for an edge.  According to some riders, Talo isn't blowing smoke when he says that his rings are actually very different from other non-round chainrings like the Rotor rings--as well as Shimano's BioPace and earlier elliptical chainrings.

Whether or not Talo's creation actually imparts an advantage, it does seem different in at least one way.  Although much of the press has called it "oval" or "elliptical", it actually looks--to me, anyway--more like a rectangle with rounded corners.  Perhaps that is helpful to certain kinds of cyclists--like Froome, who pedals at a faster pace uphill than most people can maintain on flats or downhills.

Osymetric chainring on Dura-Ace crank.  No, it's not Froome's bike--or Sir Wiggo's.

Whatever its advantages, I can't help but to think of one disadvantage Osymetrics share with other non-round rings:  compromised front shifting.  Although I never rode BioPace or other elliptical rings myself, I set up and adjusted bikes with them.  With round chainrings, you set up the front derailleur so that the outer cage is a couple of millimeters above the teeth on the largest chainring.  But doing so on the ellipsis or "corner" of a chainring means that the gap between the cage and other parts of the ring is wider, which can cause mis-shifts as well as other problems.

Then again, most riders don't shift as frequently on the front as on the rear, and usually make front shifts while pedaling at lower RPMs than when making rear shifts. Plus, mechanics for SKY and other teams have probably worked out compromises of one kind or another.

If there is to be a vogue for Osymetric or other non-round rings, it will be interesting to see how long it lasts.  While it seems that Froome and other SKY team cyclists will continue riding them, Sir Bradley Wiggins has gone back to riding round chainrings.

Now, which do you prefer:  Equipment that used by someone who won the Tour de France--or someone who was knighted?  Whose guitar would you rather have: Jimi Hendrix's or Sir Eric Clapton's?