MrCjolsen

I have two bike available to me to turn into a wet-weather commuter bike. Both have old shimano biopace cranks. Should I go to the expense of replacing them?

Is it Biopace is "bad" or just didn't show any apreciable gains in performance?

'nother

Bad? Hard to say absolutely. I think they got a bad rap because they caused problems for some people that used them. But a lot of people that used (and still use) them have not reported problems. So I don't think they're universally bad.

I would say hold on to them, give them a whirl. If you find them truly awful, then by all means replace them.

I have a similar beater bike with BioPace . . . use it maybe once/month. I do notice a difference in pedal stroke, but I wouldn't characterize it as better or worse -- just different.

BTW, here's what Sheldon Brown has to say about them and other elliptical chainrings.

cjbruin

I rode a bike with a BioPace crank from Rome to London during the summer of 1989. I rode almost every day including back to back days of 80-100 mi. Never had a problem.

GreyGoat

nothing wrong with them.. i would use them for a winter ride.. my only gripe about them at the time was that it was hard to find a bike without them . I felt no appreciable difference, and in fact ended up goin round anyway back in 86. I got them on a 86 Centurian Ironman Master that came with ultegra 600.. still have them up in the attic somewhere... I wouldn't buy replacements until you try it and find you need to..

Blackberry

I've got a biopace crank on an old moutain bike. It's back-up/rainbike but I have no intention of replacing the crank. Here's more information from Sheldon Brown:

https://www.sheldonbrown.com/biopace.html

Retro Grouch 

I think that it depends on your riding style. If you are a high cadence spinner, I doubt you'll like them. If you tend to be a bit of a masher, you'll probably love them.

alanbikehouston

I have four or five biopace road bikes and three or four with "round" chain rings. While I'm riding, I can not tell any difference. I have read articles from the '80's detailing the reseach that Shimano had as to the advantages of biopace, and their "evidence" is quite convincing. However, those "benefits" did not translate into anything noticeable in developing my progress as "world's slowest cyclist".

Around the neighborhood, I tend to run at around 70 RPM's to 80 RPM's - the "zone" that showed the most benefit in the Shimano research. On a ten mile ride down the bike trail, I run between 90 RPM's and 100 RPM's - the zone where "round" is supposed to have "an edge". Detect any difference in "feel" or performance between a 1987 Shimano drivetrain and a 1999 Shimano drivetrain? Nope.

Olebiker

I doubt you will be able to tell a difference between Biopace and round chainrings. I couldn't.

Bob Gabele

Although I no longer use Shimano stuff, I had used biopace cranks on my old Trek 1500 for years. Lots of hammerin' lots of miles...no problems.

I remember when someone started knocking them back then. I could find NO reason to swap and I would recommend that you don't either. That old Shimano stuff is really bullet proof.

Bipsycho

I am six years late to this party, but as a rider with about 120,000 miles of Biopace experience, I feel compelled to chime in. I started using Biopace chainrings in 1984. Having endured years of debilitating knee pain, I read Shimano's purported user testimonials from riders who found Biopace to be a miracle cure. My knees recovered to the point where I now ride over 5000 miles per year without pain. Was Biopace the reason, or even part of the reason? I will never know. In recent years, I have ridden increasing numbers of miles on circular chainrings, and a few weeks ago I replaced all my Biopace rings with round. The main reason I did this is to stop the scorn from riders who are sure that Biopace is inferior, or nerdy, or whatever. Those who claim that Biopace rings are incompatible with high-cadence spinning are mistaken. I started spinning mine before that urban legend spread, and I never had any problem maintaining a smooth pedal stroke.

oilman_15106

The concept is still alive and well. Stronglight has introduced a chainring they call Bioconcept. Claimed 4% increase in power and hill climbing speed. Seem not to be available in the US. https://translate.google.com/translat...%26prmd%3Divns

DVC45

I always see that claim whenever Biopace is discussed, but I can never see any reason as to why or how it is suppose to cause problems.

One of my bikes has it, and I'm fine with it. It does feel easier to climb with it.

DVC45

You're weak.

Walter

Thread resurrection!

This seems to be productive though. remember them when they were big back in the 80s. I rode Shimano (600EX) back then but not BP. Seemed to be mostly love or hate with a little meh mixed in, as I recall.

I woudn't change them until I try them.

Doug5150

BioPace is one of the mildest non-round chainrings you can buy,,, or could buy, I guess. You can still find NOS or often like-new, but they're out of production.

At one point in the past I found as big of images of as many non-round rings as I could, and made a diagram comparing the shapes. The diameters and angles of long axis are not accurate, since this was just to compare the shapes.



I think only the last two are still produced.
BioPace had at least two different generations, and the later one was more non-round than the first.
The Sugino Cycloid was so close of a copy of the BioPace that if you took side view images of each and overlaid them at 50% transparency, you often couldn't really see the difference.

There was one very-minor brand someone mentioned, that I could not find (and now I cannot recall the name, even).

There was also a UK company that made custom chainrings (with multiple mounting holes even) and many of the examples shown on their website that they made were non-round, but they didn't have a standard design to compare. They only did custom rings, so they are not represented. You'd send them a CAD file and they would cut it and put pins and ramps in it, if it called for them.

Rotor Q-rings are different than the others in that Q-rings are symmetrical about the long axis, and have multiple mounting holes. You can set them up either to increase power, or shift pedaling stress.

I use Rotor Q-Rings as I tended to suffer knee pain at the top of pedal strokes, at around 60 miles. The Q-rings have lots of holes so you can set them up however you want; I have them set 90-degrees from normal. This takes stress off the top of the pedal stroke and shifts it into the lower-end where the leg is more-straight, and prevents the knee pain until ~90-100 miles. I've never measured if it changes my power/speed, but I ride at a casual pace so that was never a concern anyway.

scirocco

What is the front shift quality like with Biopace? Seems to me that for anyone using regular Shimano cranksets with their flawless shifting, you'd have to be disappointed with Biopace. Or is the shifting not too bad?

nhluhr

I had Suntour PowerRings on my first nice mountain bike. Couldn't tell a difference when I swapped it for some CNC piece of crap that was all the rage in the 90s.

Bipsycho

I never found Biopace to pose any problem at all for front shifting. Of course, you must set the height of the front derailleur so that the bottom of the cage clears the long axis of the chainrings. Now that I have switched to circular rings, I think it is easier to avoid chain rub on the front derailleur. With Biopace rings, the chain is moving slightly up and down in the cage with each revolution, meaning that it passes through narrower and wider parts of the cage.

justkeepedaling

Biopace is fine for shifting. My friend loaned me his beater mtb for a few months while he helped me fix up my bike. I immediately noticed how weird the biopace felt (I'm a masher). I don't think I was any faster or slower, but it did engage muscles at different timing compared to a round chainring bike. Actually grew a lot of muscle and was faster than previous on my bike that he fixed up later.

tcarl

Regarding the biopace triple (28-38-48) I liked it better then round for heavy use, i.e. mountain bike and loaded touring. For normal use it was sort of weird, but you get used to it. I think it's better for lower cadences than high. I also recently started using a biopace road double (42-52) and really like it. I can spin the 42 with no problems and it doesn't feel bad or strange. Regarding the large chainrings (I have three, a 48, 50 and 52 on different bikes), I'm beginning to decide I like the biopace as well or maybe even better than round chainrings. I can't feel that they're not round, but I think they're easier on my legs.

ultraman6970

My personal experience with biopace back in the day. All or the majority of racers disliked (me included) the biopace because it did not allow you to do fast changes of cadence, for TT was fantastic because u were like 85 rpms with 52x14 and it really helped but for regular racing where u go from 85 to 135 and then u have to keep steady those 135 rpms it did not work, it was hard to accelerate and then keep high cadence for long times it simply did not work, somehow was slowing you down until you get back to 70 rpms maybe. I used it week and a half and put regular chainrings. People likes them a lot, in a climb they should work fine but again if you are racing and u need to catch somebody in a climb probably you could be in big troubles using biopace chainrings, if you cant climb probably will help. If you have slow cadence probably you wont feel the difference and even help you. For high cadence people did not work at least in my country and apparently happened everywhere in the racing community.

U can feel that the death point is almost not there, rounded pedaling works, nice concept but good for the week end warrior or people that cant do pacing, in racing the pacing is adaptable to the situation, sometimes is high and sometimes is even higher, this things cant do that.

rekmeyata

I have round and biopace on my bikes and I can spin with either. I use to race in So Calif and liked the biopace for mountains, but for an unbias report on this read this: https://www.sheldonbrown.com/biopace.html

By the way I had no problems shifting with biopace either.

MrCjolsen

So here's an update, since I'm the one who started the thread. One of the two bikes became my first fixed gear conversion. The other was part of a trade for a used, barely rideable Surly Crosscheck the following summer. Over the next four years, I replaced every part on that bike until I crashed it. Then I replaced the frame. So it's sort of the same bike. I even think it did have Biopace rings on it briefly.

Maybe I'll try them again.

Doug5150

The Suntours may have been the ones I couldn't recall... Only the two inner rings are oval though, with the smallest the mostest. I guess that followed the common opinion at the time that non-rounds were only good for low-RPM cranking.
https://velobase.com/ViewComponent.as...00984&Enum=115

Highpath was the place that made the custom rings, but he stopped-
https://www.highpath.net/highpath/cycles/ovals01.html
He notes on the History page that BioPace rings had their long-axis orientation contrary to most other examples.

I had a road bike with BioPace way back when, I had read of people alleging they caused knee problems but I tried them and don't remember it making much difference either way.

Bipsycho

As the one who restarted the thread, I am pleased to learn that the originator is still alive and participating six years later, even if the bikes have moved on.