Go Back  Bike Forums > Bike Forums > Classic & Vintage
Reload this Page >

Equipment/Product Review (1984) Shimano Biopace / Non-Circular Chainrings

Classic & Vintage This forum is to discuss the many aspects of classic and vintage bicycles, including musclebikes, lightweights, middleweights, hi-wheelers, bone-shakers, safety bikes and much more.

Equipment/Product Review (1984) Shimano Biopace / Non-Circular Chainrings

Old 07-31-20, 06:58 AM
Senior Member
Thread Starter
SpeedofLite's Avatar
Join Date: Aug 2010
Location: Henderson, NV, USA
Posts: 935

Bikes: Litespeed (9); Slingshot (6); Specialized (2); Kestrel (2); Softride (2); Cervelo (1); FELT (1); Cannondale (1); Fuji (1); Centurion (1); Schwinn (1)

Mentioned: 15 Post(s)
Tagged: 0 Thread(s)
Quoted: 234 Post(s)
Liked 385 Times in 197 Posts
Equipment/Product Review (1984) Shimano Biopace / Non-Circular Chainrings

This post contains two short articles.
The first is focused on Shimano Biopace.
The second is a brief review of other non-circular designs and the author's experience with Thetic, Bridgestone, and Durham,

WTB: Slingshot road model (1990s era; 18" L or 20" XL frame size)
WTB: Slingshot promotional documents (catalog, pamphlets, etc).
WTB: Bicycling! issue Oct 1969
WTB: Bike World Issues Feb - Nov 1972; Jun 1974; Mar-Apr 1978.
WTB: ZIPP 500 front wheel (650c clincher)

SpeedofLite is online now  
Likes For SpeedofLite:
Old 07-31-20, 07:05 AM
Senior Member
bikemig's Avatar
Join Date: Apr 2012
Location: Middle Earth (aka IA)
Posts: 17,334

Bikes: A bunch of old bikes and a few new ones

Mentioned: 140 Post(s)
Tagged: 0 Thread(s)
Quoted: 4626 Post(s)
Liked 1,011 Times in 691 Posts
Chris Froome uses oval chainrings so it's not like this idea has completely gone out of style.
bikemig is offline  
Likes For bikemig:
Old 07-31-20, 10:45 AM
Senior Member
stardognine's Avatar
Join Date: Jan 2016
Location: Arid Arizona, for now.
Posts: 2,768

Bikes: 1995 Cannondale Killer V

Mentioned: 15 Post(s)
Tagged: 0 Thread(s)
Quoted: 721 Post(s)
Likes: 0
Liked 280 Times in 211 Posts
I havenít read that whole article yet, but definitely will. Thanks for posting it. 👍😎
stardognine is offline  
Likes For stardognine:
Old 07-31-20, 11:26 AM
Velo Mule
Senior Member
Velo Mule's Avatar
Join Date: Dec 2016
Location: Long Island, NY
Posts: 876

Bikes: Trek 800 x 2, Schwinn Heavy Duti, Electra Cantilever, Schwinn Traveler, Schwinn Le Tour Luxe, Schwinn World

Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 266 Post(s)
Liked 188 Times in 142 Posts
This is an enjoyable read since we are looking at this decades later. It sure seems that Shimano put great effort into the design. I haven't tried Biopace, however, I had a bike only briefly that had a SunTour version of BioPace. I didn't get enough time on it to get a feel if it would be better for me. I also have chondromalisia, so I would, at some point like to try it out.

"Chris Froome uses oval chainrings so it's not like this idea has completely gone out of style." Is this perhaps why people have commented that he pedals like a washing machine? bikemig

I think athletes work to accommodate the equipment they use. Maybe BioPace is the domain of amateurs and tourists.
Velo Mule is offline  
Old 07-31-20, 12:23 PM
Death fork? Naaaah!!
top506's Avatar
Join Date: Nov 2005
Location: The other Maine, north of RT 2
Posts: 4,809

Bikes: Seriously downsizing.

Mentioned: 37 Post(s)
Tagged: 0 Thread(s)
Quoted: 394 Post(s)
Likes: 0
Liked 106 Times in 65 Posts
My experience concurs that they are easier on the knees.

You know it's going to be a good day when the stem and seatpost come right out.

(looking for a picture and not seeing it? Thank the Photobucket fiasco.PM me and I'll link it up.)
top506 is offline  
Likes For top506:
Old 07-31-20, 12:33 PM
The Drive Side is Within
Standalone's Avatar
Join Date: Dec 2007
Location: New Haven, CT, USA
Posts: 3,394

Bikes: Road, Cargo, Tandem, Etc.

Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 118 Post(s)
Liked 32 Times in 23 Posts
I think Iíve read this one before. For some reason I have always loved vintage magazine writing and advertising.

I like biopace on a road touring triple for the large and middle chainring, but being a 6í4Ē Clyde, the granny is going to be for mashing to some extent, and Biopace just saps my torque.

I recently switched out the inner for a circular chainring on my Trek 620 when replacing the BB ahead of a tour. My son rode it 160 miles and seemed to do great!
Standalone is offline  
Old 07-31-20, 12:36 PM
Senior Member
Join Date: Oct 2008
Location: Seattle
Posts: 1,189

Bikes: 1981 De Rosa Professional, 1988 Schwinn Project KOM-10, 1984 Univega Competizione

Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 348 Post(s)
Liked 436 Times in 257 Posts
I don't know if this is my bad pedaling form, but i have them on my old MTB and can't tell
sheddle is offline  
Old 07-31-20, 01:11 PM
Senior Member
scarlson's Avatar
Join Date: Jun 2010
Location: Medford MA
Posts: 931

Bikes: Ron Cooper touring, 1959 Jack Taylor 650b ladyback touring tandem, Vitus 979, Joe Bell painted Claud Butler Dalesman, Colin Laing curved tube tandem, heavily-Dilberted 1982 Trek 6xx

Mentioned: 28 Post(s)
Tagged: 0 Thread(s)
Quoted: 404 Post(s)
Liked 454 Times in 271 Posts
SpeedofLite Thanks for posting this article! I'm a Biopace devotee.

Originally Posted by sheddle View Post
I don't know if this is my bad pedaling form, but i have them on my old MTB and can't tell
You could have one of the "milder" flavors of Biopace, possibly Biopace II and Biopace HP. HP was "high performance" oriented toward people who liked to spin, and II was just a general mellowing-out as far as I have read.
I find that the most immediately noticeable difference for me occurs when switching back from Biopace to round rings. I end up coasting a click or two of the freehub at the top of each stroke!

Originally Posted by top506 View Post
My experience concurs that they are easier on the knees.
Me too! I have joint hypermobility - everything dislocates - so my knees dislocate a little at the top of the stroke (painless in the moment, but quickly leading to overuse) if I use too high a cadence or if my cranks are too long. I needed to switch to 165 cranks to stop this happening with round rings. Retrofitting Biopace rings allowed me to keep using my 172.5 TA Zephyr and TopLine Speed Stick cranks which have sentimental value to me on their respective bikes. I really went all-in for nice cranks thinking I was a 172.5 man, but turning 31 was a doozy for my knees. Biopace saved my bike parts investment.

Originally Posted by bikemig View Post
Chris Froome uses oval chainrings so it's not like this idea has completely gone out of style.
His chainrings are clocked such that the high gear is in the middle of the stroke, the opposite of Biopace. But he's an animal. I can't imagine my knees lasting five miles on a bike like that. This stuff is all so personal and quite possibly a lot of it is subjective! But I think there's real tangible benefit in them continuing to exist for people with joint problems.

Last edited by scarlson; 07-31-20 at 01:21 PM.
scarlson is online now  
Old 07-31-20, 06:19 PM
Me duelen las nalgas
canklecat's Avatar
Join Date: Aug 2015
Location: Texas
Posts: 11,695

Bikes: Centurion Ironman, Trek 5900, Univega Via Carisma, Globe Carmel

Mentioned: 184 Post(s)
Tagged: 0 Thread(s)
Quoted: 3714 Post(s)
Liked 1,320 Times in 869 Posts
I used a set of Biopace 52/42 chainrings on a 1993 Trek 5900 road bike most of 2019 and part of this year before disassembling that bike for an overhaul (still waiting for some parts). I liked 'em, although it required some adaptation.

I found Biopace worked best for me with shorter cranks (170mm, which was short for me) and slower cadence. Before 2019 I was a spinner, usually 90 rpm like clockwork, sometimes 100 rpm on climbs, 130+ rpm on fast downhills without coasting. But Biopace felt better to me with a slower cadence. I gradually adjusted by pushing harder gears around 75 rpm. Seemed to improve my stamina as well, so I rarely spin anymore even with my other bikes using conventional round chainrings.

The one quirk I experienced was trying those Biopace 52/42 rings with a 172.5mm crankset. Within a couple of weeks I had some knee twinges. Switching back to the 170 cranks resolved that problem. I usually prefer 172.5 and 175 cranks on my bikes with round chainrings.

I suspect that when some cyclists experience knee pain with Biopace, they may have encountered a similar quirk and didn't experiment with different crank lengths to see if it helped.

Some folks also report better results by reorienting the Biopace rings on the crank spider. The options are pretty limited. I tried that and it worked okay on the big ring but felt odd on the smaller ring. Probably because the big Biopace ring eccentric shape isn't as oblong as the smaller rings. Eventually I switched back to factory orientation and that felt fine to me.

Changing the orientation of the big Biopace ring can also lead to some chain drops on shifting because the chain catch doodad is on the chainring rather than on the crank. But I was able to minimize chain drops by carefully tweaking the front derailleur so it wasn't a big problem.

Newer style eccentric chainrings offer more variations in orientation, so those might work better for some folks.
canklecat is online now  

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information -

Copyright © 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.