"Osymetric" chainrings won the bronze in the Olympic TT this year.
Should be interesting to see if these catch on or end up in the bargain bin like Biopace rings.
When Bobby Julich crossed the finish line just 26.45 seconds behind teammate Tyler Hamilton in Wednesday's Olympic individual time trial, it wasn't just a victory for a man and his country-technology also won in the streets of Athens.
Helping to power Julich's bike were two very unusual chainrings that could very well transform the way we propel our bicycles in the future. Julich was riding a pair of French made, out-of-round, "Osymetric" chainrings which Julich claims have helped him all season.
Now before you say, "Biopace," think again. In a phone interview with VeloNews from France designer Jean-Louis Talo was clear to point out that his patented out-of-round chainrings are considerably different that Shimano's original Biopace and Biopace II chainrings.
"Biopace did very little to address the dead-spot in a rider's pedaling stroke," Talo asserted. "My chainrings are designed to optimize the power portion of the stroke while minimizing the dead-spot. If you look closely, you can see my chainrings aren't just oval or elliptical as others have been, but shaped entirely to take advantage of a rider's leg musculature. The geometry we use is two successive curves having a unique symmetry, both with a central point of rotation. When the pedal is up [at 90 degrees] a rider's strength is minimal so the ring radius is small as well. When the pedal comes near to horizontal, the rider's strength is more, so the chainring is bigger to take advantage of that. Unlike Biopace, my rings constantly change radius to take full advantage of the complete power stroke of a rider. This is the first time this has been accomplished in a chainring."
Should be interesting to see if these catch on or end up in the bargain bin like Biopace rings.