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Review - Shimano Biopace Crankset

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Review - Shimano Biopace Crankset

Old 11-24-20, 07:40 PM
  #76  
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Originally Posted by canklecat View Post
The 52/42 sets were common as dirt on late 1980s road bikes with Shimano groups -- usually 105 and 600 -- from several makers. Many folks took 'em off and stuck 'em in a closet, sold, gave away or threw them away. The 52/42 road group seemed to be more common than the triples equipped on some mountain bikes.

I got a set from a friend after mentioning I was curious to try Biopace. He put a set on a frame I bought from him in early 2019.

I rode that bike for almost a year, switching between that bike and my '89 Centurion Ironman with conventional round chainrings (although I had switched that Ironman from 52/42 to 50/38 and 52/39, depending on my mood and expected elevation and wind conditions.)

So I was able to compare the perceived effort over dozens of rides on the same routes, between the bike with 52/42 Biopace and the other with round rings, both with 7-speed 13-28 freewheels or cassettes. That's why I was surprised to find the 42T small Biopace had a perceived effort on climbs comparable to my 38 and 39T round chainrings.

But I was still skeptical about the effect of bike weight and other factors, so I swapped the Biopace rings over to the Ironman and rode that for a couple of months. Same perceived effort -- the 42T Biopace felt more like a 38 or 39 round ring.
But did the biopace feel more efficient?
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Old 11-24-20, 08:08 PM
  #77  
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Originally Posted by Moisture View Post
But did the biopace feel more efficient?
The Biopace rings *felt* weird at first. A bit surge-y or pulse-y. Took me a few rides to adapt my cadence to suit the chainrings.

I don't trust my perceptions regarding efficiency and deferred to the data. The data indicated Biopace was slightly more efficient for me, comparing data for the same routes over dozens of rides.

I do recall that when I rode the Biopace rings exclusively for a month or so and then returned to my bike with round chainrings, the round rings *felt* less efficient, as if part of the stroke was doing little or nothing. But, again, I trust the ride data more than perceptions, and I may simply have been missing the surge/pulse feel I'd become accustomed to.

And without a power meter, wind tunnel and complete data... it's still all subjective.

Subjectively, I felt like the Biopace rings worked for me. So I'd consider other eccentric rings for at least one of my bikes.
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Old 11-25-20, 02:50 AM
  #78  
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Originally Posted by canklecat View Post
The Biopace rings *felt* weird at first. A bit surge-y or pulse-y. Took me a few rides to adapt my cadence to suit the chainrings.

I don't trust my perceptions regarding efficiency and deferred to the data. The data indicated Biopace was slightly more efficient for me, comparing data for the same routes over dozens of rides.

I do recall that when I rode the Biopace rings exclusively for a month or so and then returned to my bike with round chainrings, the round rings *felt* less efficient, as if part of the stroke was doing little or nothing. But, again, I trust the ride data more than perceptions, and I may simply have been missing the surge/pulse feel I'd become accustomed to.

And without a power meter, wind tunnel and complete data... it's still all subjective.

Subjectively, I felt like the Biopace rings worked for me. So I'd consider other eccentric rings for at least one of my bikes.
Inheritly, I think that biopace is more efficient in the sense that it certainly helps to promote healthier cycling habits.

Regardless, it still mostly depends on how its used and the way you time the most powerful part of the stroke. I definetely feel like I am getting an increase in smoother power delivery due to the fact that I am focusing on working with the natural power delivery
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Old 11-25-20, 09:37 AM
  #79  
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Originally Posted by Moisture View Post
Shimano put tons and tons of development effort into Biopace.
Yeah, back in the late 80s/early 90s. To my knowledge, they've abandoned it since. Several companies have since then refined the concept, marketed and sold them. I myself started using oval rings first with Rotor 10 years ago then again with Wolftooth and Absolute Black versions. Yeah they're oval but the power delivery on the cranks is better than the old Biopace.
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Old 11-25-20, 05:44 PM
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Originally Posted by Moisture View Post
Inheritly, I think that biopace is more efficient in the sense that it certainly helps to promote healthier cycling habits.
In my 35 years of adult cycling i've been known to drink, smoke and cuss on the bike - shoulda been riding BioPace to fix that. Whoda thunkit!

Learn something new every day on this General Cycling Forum. No BS.
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Old 11-25-20, 05:46 PM
  #81  
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Originally Posted by Moisture View Post
Inheritly, I think that biopace is more efficient in the sense that it certainly helps to promote healthier cycling habits.

Regardless, it still mostly depends on how its used and the way you time the most powerful part of the stroke. I definetely feel like I am getting an increase in smoother power delivery due to the fact that I am focusing on working with the natural power delivery
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Old 11-25-20, 07:36 PM
  #82  
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Originally Posted by commo_soulja View Post
Yeah, back in the late 80s/early 90s. To my knowledge, they've abandoned it since. Several companies have since then refined the concept, marketed and sold them. I myself started using oval rings first with Rotor 10 years ago then again with Wolftooth and Absolute Black versions. Yeah they're oval but the power delivery on the cranks is better than the old Biopace.
You think after reading this thread people would understand the difference between Biopace and the current crop of non-round chainrings. Biopace was trying to help less experienced riders that didn't really know how to pedal like more seasoned riders...who didn't know how to 'spin'. It was trying to smooth out their less-than-smooth pedal stroke. The current rings are designed to make more of the power portion of a riders pedal stroke. When you get to the point in the stroke where you make the most power the chainring becomes 'bigger' and pulls more chain. Biopace was never trying to do this.
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Old 11-25-20, 08:55 PM
  #83  
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Originally Posted by Moisture View Post
I definetely feel like I am getting an increase in smoother power delivery due to the fact that I am focusing on working with the natural power delivery
Is it just me, or is this sentence gibberish?
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Old 11-25-20, 10:04 PM
  #84  
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Originally Posted by Koyote View Post
Is it just me, or is this sentence gibberish?
The latter.
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Old 11-26-20, 06:33 AM
  #85  
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Can someone explain how biopace changes the tooth count throughout the pedal stroke?
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Old 11-26-20, 06:49 AM
  #86  
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Originally Posted by Moisture View Post
Can someone explain how biopace changes the tooth count throughout the pedal stroke?
Biopace (and other oval rings) changes the effective diameter throughout the rotation.. And tooth count is the term we cyclists use in place of diameter when talking about rings and cogs.
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Old 11-26-20, 06:59 AM
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Originally Posted by Kapusta View Post
Biopace (and other oval rings) changes the effective diameter throughout the rotation.. And tooth count is the term we cyclists use in place of diameter when talking about rings and cogs.
So biopace is the opposite? The diameter decreased at the powerful part of the stroke and uses this energy as momentum to get through the less powerful part?
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Old 11-26-20, 07:18 AM
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Originally Posted by Moisture View Post
So biopace is the opposite? The diameter decreased at the powerful part of the stroke and uses this energy as momentum to get through the less powerful part?
Opposite of what?
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Old 11-26-20, 07:30 AM
  #89  
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Originally Posted by Kapusta View Post
Opposite of what?
The orientaion of the elliptical shaped ovals is the opposite of other typical oval chainring designs, right?
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Old 11-26-20, 07:46 AM
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Originally Posted by Moisture View Post
The orientaion of the elliptical shaped ovals is the opposite of other typical oval chainring designs, right?
Different, not necessarily opposite.

This has been discussed extensively in this thread. Have you missed all the references to “clocking”?

Last edited by Kapusta; 11-26-20 at 09:05 AM.
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Old 11-26-20, 07:57 AM
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Originally Posted by Moisture View Post
So biopace is the opposite? The diameter decreased at the powerful part of the stroke and uses this energy as momentum to get through the less powerful part?
Originally Posted by Moisture View Post
The orientaion of the elliptical shaped ovals is the opposite of other typical oval chainring designs, right?
This might be the kind of thing you should understand before posting a "review." Then this thread could've been a lot shorter.
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Old 11-30-20, 01:47 PM
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I really liked my Biopace back in the day and was disappointed when I was told it was no longer available and all of the stories that dissed them. Going back to roud rings was uncomfortable. Then I heard they were very expensive.

Does anyone make a close facsimile?
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Old 11-30-20, 04:50 PM
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today Nov. 30, 2020 over 135 Shimano Biopace rings/sets on E-bay.
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Old 11-30-20, 05:11 PM
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today Nov. 30, 2020 another company introduces their new version of non-round chain rings with a clocking angle hitherto unknown to mankind.
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Old 11-30-20, 06:54 PM
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Originally Posted by jimrno View Post
today Nov. 30, 2020 over 135 Shimano Biopace rings/sets on E-bay.
Hi jimmo,
How would I know if it would fit my crankset?
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Old 11-30-20, 07:33 PM
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Originally Posted by alanf View Post
Hi jimmo,
How would I know if it would fit my crankset?
Most (maybe all, but there's a lot of bike stuff I've never seen) Biopace double chainring sets for road bikes were 130 BCD, usually 52/42 chainrings. Catalogs show there was a Biopace 50T large ring but I've never seen one. With the common 130 BCD crank spiders we can fit a 38T small chainring, but only in conventional round configuration. The eccentric shape of the 42T Biopace is already effectively comparable to a 38T round chainring in the narrower sides where, theoretically, the legs are putting out less power. The elongated ends can be oriented to correspond with the strongest part of our pedal stroke.

Most mountain bike triple Biopace chainrings were 110 BCD for the middle/outer large chainrings, 74 BCD for the smallest chainring, usually 48/38/28. I've never owned a set but might eventually snag a set to try on my 1990s MTB instead of the Exage round triple set with 50/40/30 chainrings. Just curious, I doubt it would make much difference. But I'd want 170 cranks rather than the 175 I have now.
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Old 11-30-20, 07:38 PM
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Does it make sense to adjust the chainrings so that the teeth count increases at the powerful part of the stroke?
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Old 11-30-20, 07:51 PM
  #98  
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Originally Posted by Moisture View Post
Does it make sense to adjust the chainrings so that the teeth count increases at the powerful part of the stroke?
Yes, if you prefer to pedal with a high cadence. No, if not.
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Old 11-30-20, 09:47 PM
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Originally Posted by Moisture View Post
Does it make sense to adjust the chainrings so that the teeth count increases at the powerful part of the stroke?
That would be the opposite of what Biopace was meant to.
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Old 12-01-20, 06:34 AM
  #100  
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Originally Posted by canklecat View Post
Most (maybe all, but there's a lot of bike stuff I've never seen) Biopace double chainring sets for road bikes were 130 BCD, usually 52/42 chainrings. Catalogs show there was a Biopace 50T large ring but I've never seen one. With the common 130 BCD crank spiders we can fit a 38T small chainring, but only in conventional round configuration. The eccentric shape of the 42T Biopace is already effectively comparable to a 38T round chainring in the narrower sides where, theoretically, the legs are putting out less power. The elongated ends can be oriented to correspond with the strongest part of our pedal stroke.

Most mountain bike triple Biopace chainrings were 110 BCD for the middle/outer large chainrings, 74 BCD for the smallest chainring, usually 48/38/28. I've never owned a set but might eventually snag a set to try on my 1990s MTB instead of the Exage round triple set with 50/40/30 chainrings. Just curious, I doubt it would make much difference. But I'd want 170 cranks rather than the 175 I have now.
Why don't you like the 175 arms? Whats your inseam?

I think your current front teeth count should work pretty great for a variety of different needs, depending on what sort of range you got going on in the rear

The biopace 28/38/48 crankset could be worth a try if you want slightly better efficiency in each gear. Maybe fine tune your pedaling habits a little. I'd say it's worth a try just for fun- sort of like testing out different length stems.

One thing to note - I've tried testing fitting the triple chainring crankset onto both my bikes and the smallest chainring did not clear the chainstays on either bike. You need a certain length bottom bracket spindle it seems.
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