Non-circular chainrings aren’t anything new. The first designs emerged way back in the 1890s and in recent decades several brands have brought their own versions to market. Shimano’s Biopace, available in the 1980s and 1990s, is one of the best-known examples, but more recently, brands like AbsoluteBlack, WolfTooth, Rotor, and Osymetric have all tried their luck in this space.
Over the years, various riders have sung the praises of non-circular chainrings, not least four-time Tour de France champion Chris Froome and his once-teammate Bradley Wiggins, both of whom won the Tour on Osymetric rings. In fact, go back to the early 2010s and you'll find a handful of riders (many of them from Team Sky) using non-circular rings.
Others, meanwhile, have long dismissed non-circular chainrings as more of a marketing gimmick or a solution looking for a problem.
So do non-circular chainrings actually offer any benefits? Or can we safely ignore them as we push ever onward in our quest for performance gains?
A bunch of researchers out of Portugal and Spain might have some answers for us.
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