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Adaptive Cycling: Handcycles, Amputee Adaptation, Visual Impairment, and Other Needs Have a need for adaptive equipment to ride to compensate for a disability or loss of limb or function? This area is for discussion among those of us in the cycling world that are coming back from traumatic circumstances and tell the world, "No, you are not going to beat me down!"

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Old 09-27-11, 03:53 PM   #1
Sixty Fiver
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Shimano Biopace - For Those Aching Knees.

Those of us who were riding in the mid eighties probably remember when Shimano introduced their revolutionary Biopace chain rings and while many of us really liked them they did not gain widespread acceptance in the competitive world, Shimano's marketing was poor, and there were more than a few skeptics and critics.

I once thought Sheldon Brown and I were the only two people on the face of the earth who shared an appreciation for Biopace and actually joked with him about this on a few occasions.

The Biopace design is not an oval crank but rather, a computer designed egg shaped curve which in practice engages the smallest radius during the horizontal power stroke and engages the larger radius when the cranks are vertical.

This causes the leg to accelerate during the power stroke by lowering the gearing a little and when the load on the leg is highest and then slows the leg as it comes back up at which point the opposite leg will be beginning it's power stroke. This reduces stress when the leg changes direction which i also beneficial.

I have a left leg that is not "all there" and a right leg that does about 80% of the work so it can get highly stressed when one has to ride into the wind or climb.

I have been using Biopace cranks since they stopped making them and had a set on my extracycle as the design is quite good for low rpm climbing but is also good for those who can maintain a higher steady cadence and can actually smooth out a less than perfect pedaling technique.

Before the accident I was looking at competing at a master's level so knew how to spin and could spin some monster gears while now I usually run a lower gear and still spin like a gerbil on crack, albeit with one good leg.

As a bicycle mechanic I have encouraged those with knee issues to keep their Biopace cranks when other folks have told them to remove them and have been thanked for this as they are easier on knees.

I ruptured the bursa in my left knee 5 years ago and the first bike I rode afterwards was my Biopace equipped touring bike as running the same gearing on my mountain bike was far too painful.

I recently installed a Biopace crank on my commuter, which is the sister to my touring bike as I had been developing knee pain and was having problems maintaining a smooth cadence as my left leg would either stall or sometimes have powerful muscle spasms.

It has made an amazing difference in reducing that knee pain and smoothed things out a great deal so thought anyone with a similar imbalance issue or anyone who is really pedaling one legged might appreciate this information.

You cannot buy these chain rings new but there are lots of them on the second hand market and many shops will just give them away.

I am sure I have enough spares here to give some away to anyone that might want to try this.
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Old 09-27-11, 06:57 PM   #2
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I've seen similar rings, not sure what brand they were. They were drilled so you could mount them in any orientation. It makes me wonder what difference it would make on hip joint pain?
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Old 09-27-11, 09:51 PM   #3
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I've seen similar rings, not sure what brand they were. They were drilled so you could mount them in any orientation. It makes me wonder what difference it would make on hip joint pain?
Perhaps Rotor rings... the non round chain ring has made a bit of a comeback of late and is seeing success at the professional level.

Still sad that a design like Biopace was discontinued as it should have had broad appeal to many in the general cycling population and my own experience is that there are additional benefits for those with joint issues.
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Old 09-28-11, 01:45 AM   #4
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Will Biospace rings fit on most any crankset? I'd love to try a single if you happen to have a little one in 64BCD (four arm) After eight knee surgeries, and one replacement (so far) this might be right up my alley. Am currently using a 20T ring, but would try a 22T or 24T if you happen to have one about?

If more work is involved, may I get details please?
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Old 09-28-11, 06:17 AM   #5
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[QUOTE=Sixty Fiver;13287955]Perhaps Rotor rings... the non round chain ring has made a bit of a comeback of late and is seeing success at the professional level.

Check out www.OsymetricUSA.com these rings reduce the dead spot and really help with knee and hip pain and weakness issues.
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Old 09-28-11, 07:36 AM   #6
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Will Biospace rings fit on most any crankset? I'd love to try a single if you happen to have a little one in 64BCD (four arm) After eight knee surgeries, and one replacement (so far) this might be right up my alley. Am currently using a 20T ring, but would try a 22T or 24T if you happen to have one about?

If more work is involved, may I get details please?
Biopace did not come in a 4 bolt 64 bcd pattern... it predates this and comes in 110 bcd (touring / atb) and 130 bcd(road)
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Old 09-28-11, 09:49 AM   #7
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Biopace did not come in a 4 bolt 64 bcd pattern... it predates this and comes in 110 bcd (touring / atb) and 130 bcd(road)
Thank you for the info though. Would you then suggest "Q" rings? Is this the same theory?
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Old 09-28-11, 10:00 AM   #8
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Thank you for the info though. Would you then suggest "Q" rings? Is this the same theory?
Q rings work on the same principle... have yet to try them but reviews have been very good.

Nice that they sell single chain rings.
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Old 09-28-11, 05:40 PM   #9
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hi there Mr 65er,
You may have read my posts on Biopace (I really didnt like them, really) but your comments of it being beneficial with your one gimpy leg perked my interest (please read on, despite my sense of humour). Our daughter has a leg that has issues that will be with her her whole life, and part of that does entail a lot less strength. You know, I would never have thought again of Biopace being possibly a help for her, but this does makes complete sense when one leg is doing the lions share of the work--so thanks for putting this out and I will very much keep it in mind down the road as she gets older and hopefully bikes more. This summer was a watershed moment for her with biking, and I have thought often of how I would cobble together something down the road to help out with things (had thought of perhaps having one crank shorter, as her bad leg is shorter too)

gimpy humour aside, thanks alot for the heads up on this!
cheers
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Old 09-28-11, 05:50 PM   #10
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hi there Mr 65er,
You may have read my posts on Biopace (I really didnt like them, really) but your comments of it being beneficial with your one gimpy leg perked my interest (please read on, despite my sense of humour). Our daughter has a leg that has issues that will be with her her whole life, and part of that does entail a lot less strength. You know, I would never have thought again of Biopace being possibly a help for her, but this does makes complete sense when one leg is doing the lions share of the work--so thanks for putting this out and I will very much keep it in mind down the road as she gets older and hopefully bikes more. This summer was a watershed moment for her with biking, and I have thought often of how I would cobble together something down the road to help out with things (had thought of perhaps having one crank shorter, as her bad leg is shorter too)

gimpy humour aside, thanks alot for the heads up on this!
cheers
This or something like rotor rings and perhaps an orthopaedic insert might provide a solution... many people have legs that are of different lengths and have inserts made up.
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Old 09-28-11, 08:34 PM   #11
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yes there is that too (inserts) but what I really find interesting is how the oval shape would be of help exactly as how you describe it for your leg that does most of the work. I you havent read my posts concerning Biopace, basically it was about how my Kuwahara had them when I bought it in 90. Used them that summer, so am familiar with how they feel and how they do their thing, I just never liked how they felt for my knees.
I am pretty much convinced it was a cadence thing. I seem to remember that at a certain cadence things just started getting too jumpy and jerky for my knees, and it was pretty much immediate when I went back to round rings, and suited me much better.

Interesting in my recollection of it goes completely against your take on a higher cadence. That said, I really can see how it helps you in the transition phases. Im still wary of the non circular thing due to the knee problem I had that summer, but have to admit that your topic has opened up my mind to them again.

Sorry but I'm not sure which leg it is helping the most-- do you find it helps your strong leg that is doing most of the work (as you put it, it get stressed with wind or uphills) or is it helping with the left leg that is inherently weaker (so helping with the transition phases of the circular pedal motion) ?
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Old 09-28-11, 09:18 PM   #12
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Sorry but I'm not sure which leg it is helping the most-- do you find it helps your strong leg that is doing most of the work (as you put it, it get stressed with wind or uphills) or is it helping with the left leg that is inherently weaker (so helping with the transition phases of the circular pedal motion) ?
Helps with both... my left leg does not transition well and there are some dead spots in that pedal stroke (some muscles get no signal) but can push some through a limited range and helps the right leg when it is doing the heavy lifting (wind and climbs and towing).

Most of my riding is done with clipless pedals as my left foot likes to wander off the pedal... if I do not use these I have clips and straps or really toothy BMX half step pedals but won't use these if I am riding any kind of distance.

My ride home today was pretty brutal... worked for a few hours re-tapping and facing a bottom bracket which put a lot of stress on my back and hit the wall there and then had to ride into a 25mph cross / headwind all the way home.

I am a hurting unit tonight.
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Old 09-28-11, 10:29 PM   #13
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thanks for the info. Know about the "no signal" thing, same with the wandering. Have set up a simple plastic support on that pedal to help with wandering, a vertical as well horizontal piece of plastic,that does teh job with a clip and strap. At some point some really easy release spd will be good (like my 20 yr old pair of Shimanos) or at least to try, if she wants to.
40k winds....ugh. I have read of how much you commute...
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Old 10-02-11, 07:00 AM   #14
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I was specifically told to look into Biopace rings when I first started riding after my amputation (ca. 1990-91). I've got a Van Ness rotationplasty, which means I can't bend my right leg much more than about 90 degrees (though there are ways to get around that). My right q(g)uads are also much less developed. I was told that the Biopace rings might help -- I was under the impression that it was to help with the rotation limitation of my right leg, but in retrospect it may have been to reduce strain on my left knee, too.

Haven't ridden with one for years, though. I'd be interested in experimenting with one. Hmmmm.
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