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Old 08-29-12, 08:43 AM   #1
jonainmi
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Shimano Biopace and other "non-round Chainrings"

I ran across this on the interwebs while looking into the Q-rings. This is, as far as I can tell, the only scientific study on the subject of non-round chainrings.

I searched the forum for "Biopace", but it returned a bunch of threads that only refereed to it in passing, and I could not find one that was just for elliptical chainrings. If there is one, let me know, and I will move the link there.

What are your experiences with biopace and other elliptical chainrings? Do you love them? Hate them? Want to try them? Any shifting problems?



http://www.noncircularchainring.be/p...elease%202.pdf
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Old 08-29-12, 09:10 AM   #2
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None of the above but I did notice that most riders in the time trial and track events in the London Olympics seemed to be using elliptical rings...
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Old 08-29-12, 09:14 AM   #3
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Biopace, a very subjective topic. "Bad for knees, knees not effected, not good for high cadence, doesn't effect cadence" etc. I used to ride them in the 80s, don't remember any issues with them, probably changed them because they went out of style. I do have some biopace rings, I may install them and see what I think now, I'm guessing for the riding I do it won't make a difference. If you have some give them a try and see how they ride for you. Lots of 80s mtb were spec'ed with them and they are easy and cheap to find. I guess some folks think they look dorky and change them for that reason, but probably not as many C&Vers are concerned with the dorkiness factor as other segments of the cycling community. Oh yeah, the biopace rings need to be mounted in a specific relationship to the cranks, but I can't recall off the top of my head what it is. If you get/try some let us know what you think.

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Old 08-29-12, 09:24 AM   #4
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I've had them both, and jumped back and forth from a bike with and a bike without the Biopace rings. I could tell very little, if any difference. At my performance level(low) I don't think it really matters.
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Old 08-29-12, 09:32 AM   #5
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wow so biopace IS really worse than circular.. by 0.2% lol
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Old 08-29-12, 09:39 AM   #6
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Frantik, I know, I was surprised to find that none are really that much better than round.

I have some Biopace on a diamondback topanga that I am in the process of building. I can not wait to try it out, but was interested to find this paper on the matter.
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Old 08-29-12, 09:42 AM   #7
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I have several different Biopace rings (all steel so I haven't used them) and some SR Sakae Oval Tech rings that also haven't gone on a bike. I'm working on a Peugeot hybrid right now and am planning on doing a radical 48-28 set up with some alloy Stronglight BioStrong rings. I pulled these out of a box at the LBS at no charge and have been waiting for something to put them on. The middle ring was unfortunately missing which is why I'm going to try it with what I have. Just riding it on the road in the very eliptical small ring I don't notice much of a difference.

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Old 08-29-12, 09:43 AM   #8
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None of the above but I did notice that most riders in the time trial and track events in the London Olympics seemed to be using elliptical rings...
I noticed that as well. Maybe there is something to it, even if it is just placebo effect.
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Old 08-29-12, 09:46 AM   #9
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Frantik, I know, I was surprised to find that none are really that much better than round.

I have some Biopace on a diamondback topanga that I am in the process of building. I can not wait to try it out, but was interested to find this paper on the matter.
It's funny that biopace is the only one that is worse. I wish they had data on the other makes of biopace and had tried to find an "optimal" position. I was contemplating experimenting with putting a biopace ring on a pedicab to see if it would save my knees at all, but now I definitely will NOT be doing that :-p
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Old 08-29-12, 09:48 AM   #10
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I threw a set onto my Bianchi FOR the dorkiness factor.



The idea behind Biopace (as I understand it) was to ease stress on your knees, which means putting the "large" portion of the ring 90 degrees out of phase from where it would help deliver more leverage, since momentum needs to be considered. I haven't noticed a huge difference either way -- the main thing for me is to remember to spin small gears rather than to mash big ones.
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Old 08-29-12, 09:49 AM   #11
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It's funny that biopace is the only one that is worse. I wish they had data on the other makes of biopace and had tried to find an "optimal" position. I was contemplating experimenting with putting a biopace ring on a pedicab to see if it would save my knees at all, but now I definitely will NOT be doing that :-p
From what I understand, you can rotate the biopace ring one mounting point forward (I still do not know which way that is) and it will put it closer to "optimal" position. At that point, it should, theoretically, be about +.05%
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Old 08-29-12, 09:54 AM   #12
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The idea behind Biopace (as I understand it) was to ease stress on your knees, which means putting the "large" portion of the ring 90 degrees out of phase from where it would help deliver more leverage, since momentum needs to be considered. I haven't noticed a huge difference either way -- the main thing for me is to remember to spin small gears rather than to mash big ones.
That is indeed what the idea behind biopace was. Seems logical to me? As for dorkiness factor, I think it is great :-)
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Old 08-29-12, 10:07 AM   #13
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I run Biopace and love em'.

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Old 08-29-12, 10:11 AM   #14
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I have some Biopace on a diamondback topanga that I am in the process of building. I can not wait to try it out, but was interested to find this paper on the matter.
I've got them on a Topanga, a Sorrento and 2 Ascent EXs. Can't really tell any difference between them and regular rings.
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Old 08-29-12, 10:30 AM   #15
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I've never seen that study, thanks for pointing it out jonainmi! If I could offer one minor criticism to Messrs Malfait et al, it would be the commonly heard refrain in the C&V forum: "do your musculoskeletal modeling from the drive side please!"
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Old 08-29-12, 11:24 AM   #16
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I have a pair of biopace rings on a Nishiki Modulus (stock set). In the 52, you can't really tell that it's not round, but switching from that to a cannondale with a round 52, you can tell a difference in pedaling. The little ring (42? I think) is also biopace, and on that one you can really feel the changes in cadence as you go around the ring - especially at faster RPM (which for me is 110 or so).

I also have a Nishiki touring bike that was pre-biopace. It has a round 52 ring, but the other two rings are elliptical (I want to say they're 36 and 46). Those are just weird - you spin super fast going down in the pedal stroke, but then kinda laze along on the top. It gives the illusion that you're spinning faster than you really are; however, you really do get some nice pulling power with the 36 - more than expected with the gears you're given.
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Old 08-29-12, 11:36 AM   #17
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I've never seen that study, thanks for pointing it out jonainmi! If I could offer one minor criticism to Messrs Malfait et al, it would be the commonly heard refrain in the C&V forum: "do your musculoskeletal modeling from the drive side please!"
You are welcome. This is the first time I have seen it as well, but it appears to be older...

From what I can gather, there seems to not be much of a difference between non-round rings, and round rings.
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Old 08-29-12, 11:38 AM   #18
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For low cadence, say 60 rpm or less (like slogging up hill, Biopace or Rotor work ) but not so much that I need them. For spinning, no.
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Old 08-29-12, 01:18 PM   #19
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couldn't tell the difference either. FYI, I have a set of biopace chainrings from an old Trek if anyone wants .... can't do anything with 'em. Local to NYC can have 'em free.
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Old 08-29-12, 02:48 PM   #20
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I ran BioPace triple for a while and really didn't notice much difference once I got used to pedaling it. The granny was most noticeably different and I didn't care much for the out-of-round cranking on it, but the middle and tall rings were fine.
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Old 08-29-12, 03:42 PM   #21
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I have Biopace on my 1988 Cannondale, I really can't tell the difference


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Old 08-29-12, 04:02 PM   #22
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I rode BioPace when they first came out, and felt the benefits right off; I could feel a difference in my knees, and my spin felt smoother.

Almost 30 years later, and after having surgery on BOTH of my knees (both ACL's, right MCL and meniscus) I put a set of them back on my
commuting bike. This time the benefits were more obvious... no joint discomfort at all while spinning, and much less noise from my knee joints!
My cool down is also less painful after a long ride.

I was sold on them back in the 80's, and now I have them on all of my bikes. If they're in good condition I'll take them off anyone's hands!

(74/110 BCD only, 26/36/46 preferred but if you have 28/44/50 I'll take those, too)!


Last edited by oldskoolwrench; 08-29-12 at 06:59 PM.
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Old 08-29-12, 04:35 PM   #23
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I rode BioPace when they first came out, and felt the benefits right off; I could feel a difference in my knees, and my spin felt smoother.

Almost 30 years later, and after having surgery on BOTH of my knees (both ACL's, right MCL and meniscus) I put a set of them back on my
commuting bike. This time the benefits were more obvious... no joint discomfort at all while spinning, and much less noise from my knee joints!
My cool down is also less painful after a long ride.

I was sold on them back in the 80's, and now I have them on all of my bikes. If they're in good condition I'll take them off anyone's hands!

(74/110 BCD only, 26/36/46 preferred but if you have 28/44/50 I'll take those, too!

from what i gathered, the study suggested that they should actually be harder on your knees.. but if they work for you, they work!
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Old 08-29-12, 04:57 PM   #24
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jonainmi, A very interesting read, thanks!

The article plainly points out the advantages and disadvantages of each design tested. It also allowed me to more fully understand why some cyclists rotated the the Biopace chain rings to the cyclist's positive effect. I was a little surprised at how close a Biopace chain ring compares with a circular chain ring. I can now see why the oval chain rings are becoming popular (again?) in road racing, or primarily time trialing, but I think those designs put alot of load on the joints; a case of give and take I suppose.

Brad
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Old 08-29-12, 05:06 PM   #25
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the thing that seems strangest to me is that almost all of the rings saw improvement by rotating them away from the recommended angles from their creators. i would assume the people designing these things would have found the ideal angle in their R&D phase
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