Osymetric refers to a brand of non-circular bicycle chainrings, designed to optimize power transfer and pedaling efficiency by varying the effective gear ratio throughout the pedal stroke.
Design and Principle
Unlike traditional circular chainrings, Osymetric chainrings feature a distinctive, highly ovalized, or "twin cam" shape. This design is engineered to minimize the "dead spots" in the pedal stroke (the points where the crank arms are vertical and power output is lowest) and maximize power application during the stronger phases of the stroke (when the cranks are horizontal). The unique profile aims to reduce peak muscle effort and improve cadence fluidity by effectively making the gear ratio larger during the power phase and smaller during the recovery phase, thereby smoothing out the power delivery.
History and Notable Use
Osymetric chainrings were developed by Jean-Louis Talo in France. While non-circular chainrings have existed in various forms since the late 19th century, Osymetric gained significant prominence and public attention in the early 2010s. This was largely due to their adoption by several prominent professional cyclists, most notably Sir Bradley Wiggins and Chris Froome during their multiple victories in the Tour de France. Their use by these high-profile athletes sparked widespread discussion and debate within the cycling community regarding the effectiveness and benefits of non-circular chainrings in elite competition.
Comparison
Osymetric's design is distinct from other popular ovalized chainrings, such as those produced by Rotor (e.g., Q-Rings), which typically feature a less extreme or more consistently elliptical shape. The specific "twin cam" or "figure-eight" geometry of Osymetric chainrings represents a unique approach to achieving biomechanical advantages in pedaling dynamics, aiming for a more radical alteration of the effective gear ratio throughout the rotation.