Thursday, September 3, 2015

Oval Chainrings Again

Oval or elliptical chainrings seem to be back with a vengeance, don't they?

I remember seeing ads in old issues of Bicycling magazine from the '70s for the Durham elliptical chainrings, though they were hardly the first of their type (such things were described at least as early as 1896). And they wouldn't be the last.

From a 1974 issue of Bicycling. I imagine that using a front derailleur would be impossible with such an ellipse, which might be why I've never seen these in anything but a single chainring version. Durham would also go on to market Bullseye sealed bearing derailleur pulleys and hubs.

In the smaller sizes, BioPace rings
got pretty weird-looking.
Remember Shimano BioPace? Heck, even people who didn't ride in the '80s remember BioPace. The shape was more complex than the simple ellipse of earlier attempts at un-round chainrings, but the promises were similar. Shimano pushed those things hard -- especially for mountain bikes and touring, and later even for racing bikes (with a less-radical -- that is, more round -- silhouette). And they had a lot of proponents. Lon Haldeman used them. Even Sheldon Brown seemed convinced they were worthwhile.

Other companies, like SR and Sugino, made their own versions of them. But in the end, despite all their market-dominating power, even Shimano could not make BioPace last beyond the decade. Now they're viewed like other 80s fads - like Rubik's Cubes, and Flock of Seagulls haircuts: the punchline to some age-based joke.
The less said about this the better.
In the last couple of years, though, it seems that oval, or elliptical, or whatever marketing name people come up with for un-round chainrings (BioPace was technically called a "point symmetric egg curve") -- whatever people are calling them, they're baaack.

speaking of the '80s . . .

Different proprietary shapes -- but all basically making the same claims. Eliminate the "dead spots" in the pedal stroke. Increase power. Push a bigger gear. Reduce leg fatigue. Go faster.

Look at some of the current brands:

Osymetric calls their design a "twin cam" and has what is probably the most radical silhouette of the current crop of un-round chainrings. Ridden to TdF wins by Sir Bradley Wiggins and Chris Froome. Wiggins eventually went back to round rings. Make of that what you will.

Rotor Q-rings, from the same company that just introduced us to hydraulic shifting.

Absolute Black rings remind me the most of the BioPace in their particular un-round contours - though the company insists they are totally different. (photo from JensonUSA)

Absolute Black recently put out a video to explain why their un-round rings are so effective, and how they are not the same as BioPace.

The video is approximately 18 minutes of this guy sitting at his desk . . .

. . . explaining to us why Absolute Black oval chainrings are NOT the same as BioPace.

He asks a lot of questions. "Why are we so excited by oval chainrings?" "Why ovals?" "Why ovals now?" "Why are we so confident in the ovals?" "Why do we promote ovals so badly?" (as opposed to promoting them goodly?).

You could attempt to sit through the entire 18-minute video, but if you'd like the quick and dirty summary, it goes something like this:

- These are not BioPace chainrings.
- BioPace rings weren't "correct."
- Our oval rings are "correct."
- With oval chainrings, you'll pedal "rounder" than on round chainrings.
- After 5 minutes of riding ovals, you'll feel the difference.
- If you don't feel the difference, keep riding them anyhow, and you'll notice the difference when you switch back to round chainrings.
- BioPace rings didn't work. Ours do.

And if you still are unclear, just remember, these are different from BioPace chainrings. Just look for yourself:
"As you can see, this is the difference."
There. Got it?

Now, if you're hoping for some computer-modelled comparisons to demonstrate their effectiveness, or some measurable data, or anything even remotely provable, well, you might be disappointed. Just keep in mind that there don't seem to be any independent studies that can say conclusively that un-round chainrings make any real difference. By most measurable data, they come out pretty much the same. Keep in mind that a 42 x 16 gear combination gives a person about a 70-inch gear (it will vary a little with tire size, etc.) whether the chainring is round or oval. In other words, one crank revolution will propel the bike forward the same distance. From most of what I've read (like THIS, or THIS, or THIS) even power meter data on the subject can be inconclusive.

On the other hand, it's worth pointing out that the "placebo effect" is a scientifically accepted phenomenon. I'm inclined to think that any difference felt between round and un-round chainrings is more psychological than anything else. If one could somehow come up with a way to do a double-blind test, to configure a modern road bike with a completely hidden crank -- like with some kind of fully-enclosed chain case -- and study people's perceptions, I fully imagine that most riders would be hard-pressed to tell the difference. If the test subjects believe that the rings make a difference, and if they believe they're riding a bike with the rings, then many of them will believe they can feel the difference even if it turns out that they're actually riding on normal round chainrings. It's just a hunch, but if anyone actually conducts such a study (or if one has already been done), I'd love to see the results.


  1. I had biopace on my Diamond Back Apex MTB, but never really like the sensation. I tried to like buy into the concept and like them, but they just seemed wrong to me. I ultimately gave that bike to a friend who still seems quite content with it.

  2. I still have the original Biopace chainrings on my Bridgestone MB-5, and to be honest I never have noticed any difference between them and round rings.

  3. The pictures of an oval chain ring set-up only show the right-hand side of the bike with the chain ring/right crank arm relationship. To me that looks like there maybe an advantage. But makes me wonder if you get much less input from your left leg at the same time thus any benefit from using the oval chain ring negated.

    1. The oval shape makes it even pedaling with the left leg. If there was only one "lump" in the ring yes that would only work for one leg. Not saying it is the best system or worst, only that yes, it does have equal shape to work on both drive and none drive sides. Hope this helps.

  4. I still have the original Sakae Oval-Tech rings on my Trek 400 and probably still will after they go back out of style again. The only reason that I see for changing them is to change to something more compact; my rickety old knees aren't loving the 52 tooth top ring as much these days.

  5. The only difference I can see between round and non-round rings is in shifting. It's harder on the non-round rings. Not surprisingly, it's also more difficult to set up a front derailleur, and keep it adjusted properly, when using non-round rings.

    1. I didn't mention front shifting (except for that Durham elliptical, which would probably be impossible to use with a front derailleur) but that is certainly an issue, and few people seem to talk about it. The Osymetrics would probably be the most difficult to set up among the current crop - and in fact, one of the articles I read mentions that Team Sky mechanics had to come up with a device to keep Wiggins, Froome, et. al. from dropping their chains with those chainrings.

  6. Can't comment how they do the job or don't as oval shape of my ye olde Shimano Biopace is mild in comparsion to Rotor or Osymetric monstrosity, so most of the time I don't notice if there's some difference. Sometimes I do, sometimes not. What oval chainring definitely doesn't do is help to start easier if I was stupid enough to set off from the line at fat intersection on 52/14 gear. "Beep-beep" is what I hear behind the back when it happens, lol.

  7. So here's my very specific praise for the new oval rings - make of it what you will.

    I've got a singlespeed mountain bike that I commute on, and then most days I hit some singletrack on the way home.

    Singlespeed is always about compromises, but finding a gear for dirt that isn't maddeningly spiny on pavement is tough. And because of that, I've always geared this bike a little bit too high for singletrack - it just means I have to walk a little more than I'd like.

    So I decided to try an absolutblack ring, and this summer I've been clearing stuff that I haven't for the last five years. With ss one or two teeth makes a big difference, and this ring makes tough climbs a little bit easier, while keeping the pavement cadence the same.

    It's a really marginal benefit, but for singlespeed I'll take it. I wouldn't bother with either of my geared bikes or my fixie though.

  8. Just my two-cents worth: I had a Bio-Pace double, 52/42, on one of my Mercians and I really couldn't feel any difference from a round chainring. I once had a Bio-Pace triple and I could feel the difference when I used the granny (28) ring. In fact it felt weird.

  9. Oops, old thread.
    Anyway I ride an original Bio 50/38/28 wit 14-24 six cluster on a 84 Schwinn Super Sport. Ordered it with longer cranks vs 170's, thinking 172.5 mm or 175mm arms. Haven't checked been too long ago.
    Went from a stupid stepped cluster (12 spd Super Sport)to a even stepped cluster making for a nice riding 18 spd Super Sport.If it's just a mental thing (Bio-Pace) I had a slightly improved hill riding ability against my friends of eight plus years riding together in groups.
    As mentioned above the wildly out of round rings sure look crazy like to prove a point? Bring back the mini skirts if you want to prove a point.
    I'm old don't know better at 64?
    Daughter age 23 is 4th in the U.S.A., 10th in the world as a Triathlete ending season 2017 in Chattanooga Tenn. Competed in Queensland Oz. 2016. You go girl!
    Stubborn Germans we are.

  10. Very retro thread, but the wisdom of retrogrouch shines through ... a worthwhile read.