Moisture

Because alot of those people are simply not pedalling properly (despite the fact they think they are.)

The cranks have tons of developmental effort put into them backed up by research. I pray somebody doesn't claim that they know better by incorrectly mounting the chainrings on purpose and testing it out for 15 seconds on their initial ride.

Its clearly proven that (for most of us) its a superior solution mechanically, not based on how it was marketed.

icemilkcoffee 

Biopace:


Absolute Black:


You can see that Absolute Black has the oval rotated almost 90 degree differently than the original Biopace.

Kapusta

Biopace IS the old idea. There is a new crop of oval rings out now that work differently. A fact which many on this thread seem unaware of.

As far as the difference... as has been repeated multiple times... the clocking.

Kapusta

This reminds me of the thread where a husband insisted that his wife’s saddle was fine, but she was sitting on it wrong.

”There is nothing wrong with this casserole, you are just tasting it wrong”

Trakhak

Technically, elliptical chainrings were available before the 1940s and possibly earlier; all of the earlier designs were clocked like the modern elliptical rings (optimized for high-cadence riders) and unlike the Biopace rings (optimized for low-cadence riders), as explained at length in the Sheldon Brown/John Allen dissertation posted by up-thread.

Here's an image of a 1970's chainring from the Sheldon Brown site:

Kapusta

Well that is definitely interesting.

However, what I was addressing is the new rings compared to the Biopace, which is what 99% of people who ever tried a non-round ring before ~2013 would be thinking of or have any actual experience with. For practical discussion, Biopace is the older type that nearly anyone has any experience with, and it is what peoples' opinions seem to be based on.

FWIW, that clocking is different from the modern ovals I am familiar with, such as Wolftooth and Absolute Black. Those rings are clocked somewhere between those pictured above and biopace, though a lot closer to the former.

Trakhak

Kapusta, here's a better photo of another version of the Scott Durham elliptical chainring, making it clearer that Durham's design is more extreme than but, as you say, related to the Absolute Black and other contemporary rings:

63rickert

Best thing about original Biopace was the rings wore out real quick, maybe one third the life of a regular ring. For the OP this may be a problem, as he will be seeking service parts not made in thirty years. Plus Shimano was and is always awful at supplying service parts, there never were inventories except as OEM.

Can’t follow the discussion about efficient pedal speed. All of us pedal at different speeds at different times. Mountain biking would sort of define doing lots of different things with the bike. All of the old studies about 60rpm were done with casual riders or non-riders.

Trakhak

Elliptical rings were around much earlier than I thought. Here's a picture of an 1893 Columbia bike (note, too, the suspension seatpost):

phughes

Productive?

Paul Barnard

Sometimes my tongue gets caught up in my cheek, and I can't seem to get it out.

tomato coupe

That explains the OP's attraction to them.

Kapusta

Actually, that is not the same as current ovals. The clocking is very different. take a look at this next to an Absolute Black. It is a good 45(ish) degrees off.

You mentioned high cadence. I don't think that is the primary appeal of the new rings. These are seeing most success in mountain biking, where cadence varies a lot, and the place where they seem to shine the most is on lower cadence grinds and technical sections.

phughes

I seem to have the same problem. My grip is probably too loose.

canklecat

Yup. Some folks nitpick terminology either to refute or defend their pet position on chainrings. That's why I call them all eccentric. That's an adequate one word summary, including for ovals, egg-shaped objects and the peculiarly rounded near-parallelogram shape of some smaller Biopace rings.

I suspect more people who dislike them didn't spend enough time on overall bike fit to make 'em work -- for example, trying various crank lengths as I did. But I'm not sure it's worth the hassle for most folks either. Any gains are pretty small. I only spent a lot of time on Biopace out of curiosity. And it wasn't my only road bike so I had time to fiddle around with three different crank lengths, adjusting saddle height and overall position, handlebar/stem height and reach, etc.

If I had tried Biopace with only my 175 cranks and didn't make any other changes, I probably would have dismissed them after the first sign of a knee twinge.

But after finding a setup I liked my data shows I was consistently a bit stronger on climbs and a bit faster on my usual roller coaster workout routes. And my stats have shown a slight but consistent decline this year since switching back to regular round rings.

However that decline could also be attributed to aging and bouts with a minor but persistent upper respiratory inflammation all year. Too many variables to say whether switching away from eccentric chainrings was a significant factor.

So I'm going to put the Biopace rings back on one bike and try again.

Kapusta

Where do you even get Biopace rings these days?

Reynolds 

Not oval, not eccentric:

indyfabz

I like checking in on this thread.

tomato coupe

Search for EccenTric Intelligence?

rosefarts

My windchime.

tomato coupe

A lot of studies show they make better wind chimes than round rings ... but only at low wind speed.

canklecat

The 52/42 sets were common as dirt on late 1980s road bikes with Shimano groups -- usually 105 and 600 -- from several makers. Many folks took 'em off and stuck 'em in a closet, sold, gave away or threw them away. The 52/42 road group seemed to be more common than the triples equipped on some mountain bikes.

I got a set from a friend after mentioning I was curious to try Biopace. He put a set on a frame I bought from him in early 2019.

I rode that bike for almost a year, switching between that bike and my '89 Centurion Ironman with conventional round chainrings (although I had switched that Ironman from 52/42 to 50/38 and 52/39, depending on my mood and expected elevation and wind conditions.)

So I was able to compare the perceived effort over dozens of rides on the same routes, between the bike with 52/42 Biopace and the other with round rings, both with 7-speed 13-28 freewheels or cassettes. That's why I was surprised to find the 42T small Biopace had a perceived effort on climbs comparable to my 38 and 39T round chainrings.

But I was still skeptical about the effect of bike weight and other factors, so I swapped the Biopace rings over to the Ironman and rode that for a couple of months. Same perceived effort -- the 42T Biopace felt more like a 38 or 39 round ring.

Kapusta

So I guess the answer to my question is that you find them in friends' closets and parts bins.

canklecat

Yup. You can probably get a set by offering to pay for shipping. Well, that, and maybe $10-$20. The pandemic shortages have jacked up the prices of even modestly priced Vuelta brand chainrings (equal in quality to 1980s Shimano and Suntour chainrings) to around $30-$50 each.

In 2017-'18 I bought Vuelta chainrings for only $5-$10 each via Amazon warehouse sales because the packages were "damaged." They were just plastic bags with cardboard folded over and stapled for hanging from peg hooks. There was nothing to "damage." Nowadays it's hard to find bargains in some bike components.

Reynolds 

After that, they should've introduced Biopace UHP (Ultra High Performance) with totally round chainrings.