Bio pace in 1990?
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yagamuffin
Senior Retro Guru
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Makes no sense to me either! 
As the longer diameter move from the vertical axis to the horizontal it is still pulling the same amount of chain.
Also, the pedals still remain in their usual round configuration so i don't understand how it would feel any different to pedal?
All very confusing! :?
As the longer diameter move from the vertical axis to the horizontal it is still pulling the same amount of chain.
Also, the pedals still remain in their usual round configuration so i don't understand how it would feel any different to pedal?
All very confusing! :?
thecannibal
Retro Guru
Here's what the late, great Sheldon Brown had to say: http://sheldonbrown.com/biopace.html
I, as have many others, found they hurt my knees though and they're quite widely discredited, though seems some here still like them. Suck it and see?
I, as have many others, found they hurt my knees though and they're quite widely discredited, though seems some here still like them. Suck it and see?
thecannibal
Retro Guru
yagamuffin":328oe3rc said:Makes no sense to me either!
As the longer diameter move from the vertical axis to the horizontal it is still pulling the same amount of chain.
Also, the pedals still remain in their usual round configuration so i don't understand how it would feel any different to pedal?
All very confusing! :?
With a true ellipse (which biopace isn't, IIRC) the chain wrap remains the same, but gear inches do change. Think of it as the chainring constantly morphing from a big ring which is close to the rear wheel to a small ring which is further away.
Same length chain, different gears.
That make sense?
I think that it was still around on the lower to mid range group sets in 1990 although the higher end stuff was moving away from it by then (SG on Shimano LX/DX/XT and Power Rings on Suntour).
A gimmick now just as it was then if you ask me, I saw a beauty of a modern road bike ruined by a god awful elliptical crank set in the LBS the other day :roll:
I don't believe any of the damaged knee theories though - more likely to be bad rider position set up.
A gimmick now just as it was then if you ask me, I saw a beauty of a modern road bike ruined by a god awful elliptical crank set in the LBS the other day :roll:
I don't believe any of the damaged knee theories though - more likely to be bad rider position set up.
On my modern road bike:
Chris Bell got it right with egg rings, correct shape and orientation and supreme quality. Had one set for 15 years and they look like new. The great thing is that they put the power where it's needed ie the biggest gear when your legs are pushing down on the pedals. I love em, always have.
Chris Bell got it right with egg rings, correct shape and orientation and supreme quality. Had one set for 15 years and they look like new. The great thing is that they put the power where it's needed ie the biggest gear when your legs are pushing down on the pedals. I love em, always have.
thecannibal":y88e8ivl said:yagamuffin":y88e8ivl said:Makes no sense to me either!
As the longer diameter move from the vertical axis to the horizontal it is still pulling the same amount of chain.
Also, the pedals still remain in their usual round configuration so i don't understand how it would feel any different to pedal?
All very confusing! :?
With a true ellipse (which biopace isn't, IIRC) the chain wrap remains the same, but gear inches do change. Think of it as the chainring constantly morphing from a big ring which is close to the rear wheel to a small ring which is further away.
Same length chain, different gears.
That make sense?
So....how do they change gear but they work on a SS or Fixed Gear. Do teeth fall off and jump on the while you pedal?
thecannibal
Retro Guru
Woz":19iuviah said:thecannibal":19iuviah said:yagamuffin":19iuviah said:Makes no sense to me either!
As the longer diameter move from the vertical axis to the horizontal it is still pulling the same amount of chain.
Also, the pedals still remain in their usual round configuration so i don't understand how it would feel any different to pedal?
All very confusing! :?
With a true ellipse (which biopace isn't, IIRC) the chain wrap remains the same, but gear inches do change. Think of it as the chainring constantly morphing from a big ring which is close to the rear wheel to a small ring which is further away.
Same length chain, different gears.
That make sense?
So....how do they change gear but they work on a SS or Fixed Gear. Do teeth fall off and jump on the while you pedal?
No, as the size of the chainring (yet, as I explained above, not necessarily chain-wrap) effectively changes, the number of gear inches -- the 'gear' -- also changes. I don't believe any actual witchcraft is required.
