top506

My 2x7 and 3x7 setups work great, except for the aforementioned big ring upshifts. Not enough to make me change chainrings, for the advantages outweigh this little blip, but I can see where it would sour a serious racer.
And Light Action rocks!

Top

tyler_fred

I know this isn't the ISO thread but if anyone here is interested, I have a pair of Biopace aluminum 130mm 52/42 chain rings to trade for a round 6-7spd 52T 130mm chainring, Shimano, SR, Sugino...

ThermionicScott 

I bet you're right. At least with round rings, the teeth are always in the same place wrt the FD cage. With BioPace, they're constantly rising and falling, and while they rise and fall together, you can't hit an optimized part of the FD cage every time unless you synchronize your shifting with your pedal stroke.

With friction shifting and finesse, it's much less of a problem -- you're used to "easing" the chain from one ring to another, and letting the resistance from the shift lever tell you when you're about done.

PolarBear007

I have/had BioPace (48/38/28) on my '90 Schwinn High Plains. However, i did swap out the 28t BioPace Granny gear for a 24t (which is round).

I don't notice the oval shape other than the fact that my R knee is never sore (and it has seen some serious use and surgery... ACL/Meniscus + MCL micro tears...).

The 830 Trek i have also has BioPace, but i don't ride that bike (my wife and daughter use it from time to time).

I've considered visiting some local pawn shops and snapping up however many i can just for the parts....and possible frame base for my son.

eschlwc

i dislike the look. like the crankset is bent, squashed.




'80 gran rally ... with an odd looking saddle that reminds me of a great dane

SteelCharlie

I've had them on all my MTB's and liked them fine. I also have them on a Caylor equipped w/ 80's New Dura Ace SIS. Work fine and they do seem easier on the knees but the Colnago round Campy's don't hurt much either. I used to buy the rings at the swap meets and have enough to last out my life hahaha (I hope)

retrofit

Yup. BioPace II 46-36-28.

Lazyass

Man, did they make these things in a 39T or what? I've been watching ebay all summer and haven't seen a single one. I don't have mountains so my 42/28 is plenty enough, but a 39 gives me my perfect cruising speed gear ratio.

ThermionicScott 

I think you could get a 40T/130 and a 38T/110. I've never heard of a 39T, but that doesn't rule out their existence.

top506

I'll rule it out. In 130 BCD 40t is as small as they got. Even then, it was steel ring in the OEM EX300 group.

Top

USAZorro

I tried them once. They made my legs feel drunk.

fleslider 

I Still have them on my 1987 Centurion Ironman's (Master & Expert) and on my 1986 Trek 560 along with My 1989 Diamondback APEX, The rest of the bikes have round chainrings, and i dont think it makes me faster but after putting 300+ miles on the Ironman Master, The BioPace seems to be easier on the knee's

I use to hate them then i discovered that i never gave them a chance since the early 90's .

top506

+1.
After 50 miles or so my knees will begin to twinge when riding round rings. Not an issue with Biopace.

Top

vtchuck

FWIW, Froome used oval chainrings made by Osymetric USA in the TDF. Seem to be working well for him.

retrofit

Apparently, Biopace and Osymetric rings are different in what they provide to the rider according to this VeloNews article:

verktyg 

I have Biopace rings on a number of bikes. What I found is that they add a little extra when climbing. For example I run 48T 49T or 50T x 38T chainrings with a 28T FW on a lot of my bikes.

A 42T Biopace chainring has the same feel when climbing as a 38T round chainring!

A few years ago I put this Flickr album together when I was researching Biopace cranks. It some of the many variations plus other brands:

https://www.flickr.com/photos/282672...7625130627294/

If Campagnolo had introduced Biopace chainrings they would have been the best and only way to go...

verktyg

Chas.

Deore XT 48-38-28T on a Colnago road bike...

FujiSam

I just swapped my stock Fuji crankset for a bronze double biopace crankset on my '79 Fuji Royale gravel conversion, initially because I changed the rest of my drivetrain to Shimano 600 and because it was gorgeous! After riding the last couple months, I love it! I definitely feel like I get more out of digging in through climbing strokes (off road especially).

FujiSam

Bronze biopace on the bronze Fuji Royale

Miele Man

I like Shimano BioPace chainrings for certain applications. Contrary to popular belief you CAN SPIN using BioPace chainrings.

Cheers

Cycle Tourist

Totally subjective but I liked them on the granny only. I thought they were easier to climb with a good cadence but round ones easier to spin with the help of momentum from more forward speed.

canklecat

I've been using the standard 52/42 alloy Biopace on a carbon fiber Trek 5900 for a few months. Not a huge difference from circular chainrings, but I'm not really comparing apples to apples. The bike with Biopace has 170mm cranks, and a 13-28 freewheel. The other, my '89 Ironman, has 172.5 cranks, and 50/39 circular chainrings, with 13-26 freewheel.

The Trek is about 5 lbs lighter, maybe even more, so the differences I feel and sometimes clock on climbs may be due to the lighter weight, rather than the Biopace.

OTOH, the Ironman is tuned nearly perfectly. I tinkered with it constantly for two years, right down to adjusting the rear derailleur pivot spring tension and replacing the original sintered bushing bearing pulleys with smooth as butter sealed bearing pulleys. The Ironman feels tuned to my body and is a pleasure to ride. The Trek and I are still getting acquainted, with lots of little tweaks here and there.

So overall my speeds/times are the same on both bikes on the same 20-50 mile routes. If there's a lot of climbing into headwinds, the lighter Trek tends to be a little faster -- the bar is a little lower, I'm more stretched out and aero too. Otherwise it's a tossup. I tend to average 16 mph on both bikes on the same 20-50 mile routes.
@Cycle Tourist mentioned something I've been considering -- replacing the Biopace 52T big ring with a standard circular 52T ring, and keeping the 42T Biopace for climbs. It's a subjective thing, but I seem to feel slightly more drivetrain drag in the 52T Biopace.

Ideally I'd like a 38T or 39T Biopace, but that probably isn't feasible due to the non-circular design.

I'm also toying with the idea of putting the 52/42 Biopace on my hybrid, with has 175 cranks and platform pedals. I get the impression the Biopace feel more efficient when mashing rather than spinning. That's based on personal feel. I wasn't even aware of the old stories about Biopace supposedly being optimized for cadences below 90 rpm. Usually I tend to spin around 90 rpm on my road bikes, but use a slower cadence on my hybrid with the longer cranks and platform pedals. But when I first got the Trek 5900 I rode it for a month with platforms and a somewhat slower cadence, around 70-80 rpm -- which may explain why it felt fine a few months ago, but feels different now that I'm using clipless on the Trek. But the hybrid has a 110 bcd crankset, so I'll need to replace the entire crankset to try that theory.

There's another theory I may try first, while keeping the Biopace on the Trek. Some folks say the Biopace rings work better when shifted to "time" the non-circular shoulders/flat spots differently. That may be due to personal differences in where each cyclist delivers most of the pedaling thrust. It's an easy experiment so I may try that this week.

Incidentally, no problems with chain drops or front derailleur shifts. The Trek 5900 has a direct mount front derailleur, with limited adjustments for height and angle. But no problems shifting with either the original downtube friction shifters or replacement brifters with index front shifting. The MicroShift brifters have trimmer clickstops to dial out chain rub. Pretty nifty. No problems with the Biopace design.

jdawginsc 

Shimano 105s here. Had them on my Crest Cannondale for years and hated them. Swapped them off for 600 crank last year. Now they are sitting waiting for a gravel bike project.

dim

recently bought a 1980's Miyata 1000 Grand Tourer and it has the BioPace Tripple

I was going to change the Biopace and someonet me to try it first .... that was 2000 Km ago and I'm still using them

I only have 5 speed and not too many hilhe, so I tend to stay on the big ring .... I have tried the middle ring and you can feel the 'ovalness' if that makes sense (not so much on the large ring .... I have not used the smallest ring yet)

on the big ring, cadence of 90+ RPM is no problem

Doug Fattic 

I was just organizing my stash of vintage stuff I’ve accumulated over the years and realized I have a lot of Biopace chainrings. What I recall is that over time Shimano modified them to be less oval (like Biopace II and Biopace HP) until they gave up and went back to round again. Like others have said racers bad reviews doomed them. My impression was that the concept and engineering worked for recreational riders but sagging sales caused by the reputation they had with fast guys did them in. Unfortunately they weren’t sold as a possible alternative instead of having them across the entire lineup. Shimano was ruthless about getting rid of stuff that didn’t sell no matter if it was better or not (like DD pedals and cranks).

I understand why Biopace was not popular with the fast crowd and why fit recreational riders could benefit from them. Years ago when I rode with the big boys on training rides, I had to have everything perfect (gearing, position, etc.) in order not to get dropped. I didn’t have enough strength to overcome any deficiencies. My cadence had to be higher than when I rode by myself and Biopace rings disturbed my pedaling smoothness. However when I rode with a naturally lower cadence (in the 80’s rpm) by myself I felt like they gave me an advantage.

One of my fellow framebuilders speculated that non-round chainrings might have an advantage because the lower gearing part of the rotation gave the muscles a very slight rest that might have an accumulative effect.

Last ride 76 

Of course. on a couple of bikes. no problem,