The myth of Biopace... Let's discuss

[gtRTSdh]

Shimano's idea was 90 degrees out to what makes sense. Their idea was to make the power stroke easier to give momentum through the dead points of the sorke.

As stated on this thread the more modern version, which makes a lot more sense is to reduce the chainring size at the dead point makin it easier to move through. The shimano rings can be rotated on the cranks but as they were 5 bolt, and the rings needed moving 90 degrees the alignment cannot be perfect.

 

[Woz]

If I remember correctly, the first generation are heavily ovalized, later versions less so. I think the reports of knee problems came primarily from those who turn high pedal RPM, and this led to the less-oval Biopace 'HP' designs.

I like low RPM and big gears, might be why they work for me.

+1

BITD I had the first generation, and they felt weird at a higher RPM. Mashing them made more sense. I remember an old trick of rotating the granny to give more ground control and leverage up steep claims. In hindsight, it was probably utter bull. The later generations are distinctly less oval - or should I say square! Don't use them any more....but would like to give them a go again on a SS.

 

[mechagouki]

Someone I know has them on a posh newish Yeti - super lightweight chainset, although I can't remember who by.
He's running something like a 36t ring - it looks so weird, it makes the bigger 4*tooth rings look normal!
But he's a damn good racer, and along with the pros these days, that has to mean there's something in it.

These?

They are beautiful in the flesh, but actually slightly heavier than similar priced offerings from FSA and Shimano.

 

[trickylad]

Not doing it for me I'm afraid.

 

[Carlos]

Someone I know has them on a posh newish Yeti - super lightweight chainset, although I can't remember who by.
He's running something like a 36t ring - it looks so weird, it makes the bigger 4*tooth rings look normal!
But he's a damn good racer, and along with the pros these days, that has to mean there's something in it.

These?

They are beautiful in the flesh, but actually slightly heavier than similar priced offerings from FSA and Shimano.

Yep, they're the ones. They do look cool. He's had problems with the BB but he likes the chainset. It certainly doesn't look heavy!

 

[pete_mcc]

Have to sayi love Egg rings, made by Chris Bell. I also loved biopace when I was a kid because I couldn't afford Chris' rings and you could just rotate them 90 degrees and they worked properly.

I have 20 and 25% ovality rings on my road bike, used along side a carbon chainguard (only because you can get overshifts on extreme ovality and roadie mechs)

Also use them on my Ti Fat and my commuter and the round rings on two other bikes. The only sad thing is that Chris has stopped making them as he is concentrating on other things these days, but as they last 15+ years I'm not too worried yet...

 

[makster]

The Suntour Ovaltech rings on my 87' Jamis are the ovalest I've ever ridden. Felt really weird first ride (and most of my bikes run Biopace) but I quite like like it.

Whenever I bend my knee's they make a loud cracking noise...is this related?

 

[andrewl]

Part of me suspects that if elliptical chainrings were such a good idea they'd have been invented by some bloke in a shed in Yorkshire in 1923.

They were! Well Williams in Birmingham produced them I believe. I had some in the 60's. They were a sort of angular ellipse ish.

Actually oval rings have been around since the early 1900s. I'll post a pic later...

 

[pete_mcc]

Decent chunk of history here:

http://highpath.net/highpath/cycles/ovals03.html

Chris lists the first ones as 1890, nothing in bikes are new, just reinventions with added marketing pazzazz!

 

[pete_mcc]

Here we go, 1893:

http://www.oldspokeshome.com/columbia-model-“32-1893

Even these guys got the orientation right, how did Shimano think they were right.....