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Old 06-18-12, 09:04 AM   #1
stevekk
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Do they still make anr ELIPTICAL shaped FRONT SPROCKET ?

I bought a bike years ago and it had an Elliptical Front Sprocket, actually 3 of them... for 3 speeds.
Instead of the sprocket being round shape, it is shaped like an ellipse.

It was a no name Dirt Bike, made in China, and I purchased new from Costco in Reno, NV.
Long, long time ago... maybe 25 years..??

On the sprocket it says:
Shimano,
Exage Trail,
Computer design bio-pace.


Do they still make an Elliptical Sprocket?
If not, why not?
Seemed like a good idea to me... thats why I bought the bike.

Never have ever seen a bike like it, with the "ellipse".

Thanks, Steve

Last edited by stevekk; 06-18-12 at 09:10 AM.
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Old 06-18-12, 09:07 AM   #2
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Rotor does. Don't know if Shimano still does.
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Old 06-18-12, 09:11 AM   #3
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Thanks....Do they work?
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Old 06-18-12, 12:47 PM   #4
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Thanks....Do they work?
The conventional wisdom on the Shimano version is that it depends on your peddling cadence. People who have a slow cadence tended to like them, spinners not so much. I think that at one point Shimano even made a higher end biopace crankset that was less ovalized for people who like to spin. I don't think that biopace chainrings are in current production but I think you could easily find what you want on eBay.

It's a concept that keeps popping up. A few of the Pro riders use them on their time trial bikes but I don't see everybody else jumping on the bandwagon yet.
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Old 06-18-12, 12:50 PM   #5
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I've got tons of biopace laying around.. some is really flat and some is pretty close to circular, as far as I know shimano no longer makes it.
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Old 06-18-12, 12:56 PM   #6
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Yes, they're still available but it will cost you $$. As mentioned above, Rotor makes Q-rings. If you need a small ring for a triple, your options will be very limited. http://www.rotorbikeusa.com/

A small selection of Shimano Biopace rings can also be found on Ebay.

I have some Biopace rings, but never got around to mounting them. Some people swear by oval rings, others are like 'meh'.

Some other options (Edit: just noticed than neither is selling anymore, but good info):
http://www.highpath.net/highpath/cycles/ovals/01.html
http://kingbikefit.com/why-i-am-sell...al-chainrings/

If you're handy, you can also make your own chainrings.
http://www.fleettrikes.com/giles%20p...0calulator.htm

Last edited by Recumbomatic; 06-18-12 at 01:02 PM. Reason: Update
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Old 06-18-12, 12:59 PM   #7
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Thanks....Do they work?
Bradley Wiggins thinks so, he always uses them. Wins virtually everything these days, so maybe he knows what he is doing. I'm told he favours them because he has knee problems. Whether that is true or not I don't know, but in theory they should certainly be kind to the knees...
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Old 06-18-12, 05:07 PM   #8
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Always liked riding them since they were first introduced. Since I had knee surgery a couple of years ago I can feel
a difference; it feels as if there isn't quite as much pull on my knees spinning them as compared to round chain
rings, and my cadence runs at about 95 RPM.

I want to convert all of my bikes over to them, especially the road bikes... it'll be nice to try half step gearing once
again!

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Old 06-18-12, 06:26 PM   #9
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Thanks. Learned a lot.
Good links.
I see ebay has a lot for sale under Biopace.
With good reasonable prices.

Also this... http://en.wikipedia.org/wiki/Biopace
The 2 pictures shown are exactly what mine look like.

Also learned a new word.... Chain Rings...

Last edited by stevekk; 06-18-12 at 06:29 PM.
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Old 06-19-12, 07:21 AM   #10
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... it'll be nice to try half step gearing once again!
You sure? How many cogs to you have in back?

Half step gearing made sense to me when we only had 5 rear cogs and had to make every combination count. All that double shifting today and having to remember whether to go up one or down one on the back would drive me crazy.

Today I much prefer to use a relatively close ratio cassette and think of my front chainrings as ranges for uphill and otherwise.
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Old 06-19-12, 07:24 AM   #11
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Originally Posted by chasm54 View Post
Bradley Wiggins thinks so, he always uses them. Wins virtually everything these days, so maybe he knows what he is doing. I'm told he favours them because he has knee problems. Whether that is true or not I don't know, but in theory they should certainly be kind to the knees...
I knew about Wiggins time trial bike. Does he have them on his road bikes too?
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Old 06-19-12, 11:29 AM   #12
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I rode them for a year on a 1989 Fuji Club with tight gearing. I wasn't sure why, but I liked riding that bike a lot. My cadence is usually 90 or so. I sold the bike a couple of springs ago, though.

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Old 06-19-12, 12:27 PM   #13
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Quote:
Originally Posted by chasm54 View Post
Bradley Wiggins thinks so, he always uses them. Wins virtually everything these days, so maybe he knows what he is doing. I'm told he favours them because he has knee problems. Whether that is true or not I don't know, but in theory they should certainly be kind to the knees...
I have Q-rings and like them too. And I got them for knee problems also.

I decided to try them on my 'long-distance' bike because I had knee pain at the top of the pedaling stroke on long rides. With the Q-rings you can turn them to shift the load of the pedal stroke somewhat. I have them positioned to take stress off the top-half of the stroke and more into the bottom-half. Mine is adjusted about 75-degrees away from there it would normally be used.

If it increased my speed or power I don't know, and don't care. It is more comfortable to ride though. And then my city bike felt "odd",,, so I put them on there too, and liked it better also.

------

I have some notes on past makers, but most of these are no longer made. Rotor and Osymetric may be the only two companies currently producing them.
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Old 06-19-12, 01:09 PM   #14
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I decided to try them on my 'long-distance' bike because I had knee pain at the top of the pedaling stroke on long rides. With the Q-rings you can turn them to shift the load of the pedal stroke somewhat. I have them positioned to take stress off the top-half of the stroke and more into the bottom-half. Mine is adjusted about 75-degrees away from there it would normally be used.
I'll bet it's 72 degrees. That would be 1 hole over on a 5 bolt crankset. So when your crank is vertical, where is the high point of your chainring?
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Old 06-19-12, 03:08 PM   #15
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I rode them for a year on a 1989 Fuji Club with tight gearing. I wasn't sure why, but I liked riding that bike a lot. My cadence is usually 90 or so. I sold the bike a couple of springs ago, though.
+1; My '88 Fuji has the Sugino equivalent (Cycloid) and I like 'em. My cadence is right around 90 as well. They do feel better at a lower cadence than the round chain rings on my cross bike. They're good for serious riding but the good feeling at lower cadence makes them nice to just relax with.
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Old 06-19-12, 03:56 PM   #16
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I knew about Wiggins time trial bike. Does he have them on his road bikes too?
I have certainly seen him using them on road bikes. Can't say whether he always does, I'll have to take more careful note next time I watch him.

EDIT According to Rotor, Wiggo is using O-symmetric rings. The Garmin team are all using Q-rings.

Last edited by chasm54; 06-19-12 at 04:10 PM.
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Old 06-19-12, 04:52 PM   #17
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I still use them on my Expedition bike, mine happen to be Sakae Oval Tech rings. They are typically used by lower rpm riders. I love mine on that bike and won't swap them out, interestingly enough the smallest ring is round, but it is also steel which wasn't uncommon on the MTB of that era.

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