From Newsgroup: rec.bicycles.tech

Engineer Archibald Sharp critiqued the various oval
chainring designs in his book Bicycles and Tricycles (1899).

Then in the 1970s we had Durham elliptical chainrings,
followed in the 1980s by Shimano BioPace, Sakae OvalTech and
naturally BioPace II.

But hey, maybe they all just didn't do it quite right. Hope
springs eternal:

https://bikerumor.com/reinventing-the-chainring-doug-brown-jr-spreng-reng-project-interview/

Interesting note is that the claimed efficiency improvement
is about the same as Shimano claimed 40 years ago.
--
Andrew Muzi
am@yellowjersey.org
Open every day since 1 April, 1971

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