Ovoid Chainrings
 

Someone gave me a 1987 aluminum Lotus not long ago. It has Bio-Pace type rings called, I believe, Ovoid.....I'm not surprised I'm not noticing them much.....And the last few more and more pros use the oblong rings....What is the consensus here?

They [B]seem[B] to offer some benefits for lower cadence riders and when climbing. However high cadence riders tend not to be fans,

There may also be some drawbacks relating to FD performance.

In any case, they're like double breasted suits, and come back around every 10-20 years.

I think the consensus back in the late 80's, when they came out, was that you noticed the oval shape much more on the big ring than the small ring. Sprinters hated 'em, but some time trial specialists liked them. I don't recall seeing anyone riding them who were not paid to use them, so make of that whatever you want.

They were essentially rejected after a few years, but some people (myself included) kinda liked them on the small ring for climbing. My climbing stroke is not the smoothest (especially on steep gradients) so they didn't slow me down at all when I used them.

IIRC, it was concluded that they didn't make very much difference, good or bad, and that they were largely "a solution in search of a problem".

I have a bike with Bio-Pace and one with Sakae Oval-Tech. I don't notice any difference, good or bad, when riding the big or middle ring. It's too flat around here to be able to judge the 28 tooth small ring. I normally pedal around 80-90 rpm.

Sky claims they boost Froome's efficiency by roughly 10%. I don't believe much that they say. :twitchy:

We're having a ovioid crisis, aren't we? I say ditch 'em.

There was a master's thesis done in California on Rotor's oval chain rings. The aim of the study was to disprove any advantage. The research showed zero disadvantage, and advantages ranging from 0 to 5%, i.e. "no downside." I think Rotor actually saw the study and hired the grad student.

I think I saw it in a bike magazine, and that's what I remember. I have a friend who is a very powerful masher, and he runs the Rotors on his bike and swears by them.

That's interesting. I wonder if any studies have included both Rotor/Osymetric and BioPace-style chainrings. One would think that if any advantage were found with one orientation, they would find a non-trivial drawback to the other.

Also, you should know that in the BioPace line there are at least two different degrees of ovalization, rather mild* and somewhat less mild*. I've had both and I don't really notice the mild ones but can't stand the less mild ones. I've never ridden the Oval Tech line.

*excuse my technical jargon. :P

Try spinning this puppy. At a cadence of 20 rpm and more, the bike actually started to hop...

http://www.bikeforums.net/attachment...6&d=1283956632

I spent a bit of time, one day in the mid-1980s, test-riding a Ritchey Ultra. It had BioPace chainrings on it. I thought they aided slower-cadence power up hills, but hated how it induced its own uglier motion in the pedaling when the cadence was high and I was on flatter terrain. My own preference: "standard" round chainrings.

They've been coming and going on a 10-20 year cycle since the first chain was installed on a bicycle. If they were really an improvement, they'd stay rather than fading away until the next time they are "invented".
If you are a stomper, you might like them. If you know how to spin, you probably won't. If you do find that you like them, your next purchase should be a set of used rollers. Use them to learn to spin smoothly. Your knees will thank you in the long run.

You need to post a video of this.

I'm new to the Bio-pace thing but they apparently belong on my Ironman. After a few hundred miles, I don't know if there is a real or imagined difference. I don't think that I would order replacement Biopace rings.

I like 'em. Whatever the original design parameters were my knees hurt less after 50 miles or so when riding Biopace. And I'm always looking for 130/53 and the scarce 130/40.......

Top

You obviously haven't seen every bike ever donated to a bike co-op. So much BioPace. Bike co-ops are like egg farms.

Funny how the Bio-Pace name is usually referred as when talking oval rings. Sort of like Xerox is to photocopiers.

Only ones I've experienced are Shimano's and then until this year, the '87 edition of Suntour's Ovaltech. Immediately noticeable but soon becomes fluid and routine feeling. I'm also enjoying fixed gear bikes and possibly there's a correlation in that bio physio sensation though having them or not makes no difference to me.

If that were true, imagine how bad he would be without it!

I have a biopace middle ring on a front triple on my '84 Peugeot road bike. I can't really say any thing pro or con. It's just there and is the most-used front ring. I put the triple ring on about 30 years ago.
Jon

I had a 90s (?) Bianchi Forza with Biopace rings several years ago. I was cleaning it, and noticed that the rings weren't round. I saw the Biopace sticker and Googled it, learning the story. I rode it for a year or so, until a car hit me and killed the frame. I transferred everything to a Nashbar frame, but finally sold it. I was a low cadence gear masher back in the day, try to spin lower gears, high cadence now. Now I might feel a difference, but not back then.

I find it interesting that some people SWEAR ovoid chainrings kill your knees, but there's lots of people (Top included) that find the ovoid rings are kinder to their knees.

I have 2 small BioPace rings and a round large on my 87 Schwinn High Sierra. I don't really notice the difference on the 38- but it's a marked difference on the 28. I had the SR OvalTech rings on an 88 Trek 400 for a while. I recall that I actually liked them.

I recall some post here a long time ago- a bike newb completely upset that his chainrings weren't round- he discovered it while riding and thought he broke something. It is weird to look down and see it- especially if you don't know what you're doing.

I like the "avoids" rings myself, have run shimano 105 (88 trek 560) and 600 tri color (89 fuso fr1) and always feel good on climbs or hammering but really little to no difference vs rounders. When they are part of stock builds I have always left them as is. Never given me any knee problems.

I tried to visit a local one recently, but unfortunately, it happened to be a Wednesday night and I forgot to wear a dress. :(