



Modern asymmetrical rings are designed like cams, with specific diameter variations designed to match the leverage rate and muscular efficiency of the human leg as it pushes the pedal around the crank's axis. While cycling's oral historians have preached that we all should be pedaling perfect circles, the concept is laughable. Sure, we have taught ourselves to pedal round chainrings with legs that were intended for walking and running, but step outside the narrow confines of traditional cycle-thought and it doesn't take a bio-mechanical scientist to understand that modifying the leverage rates of the pedal circle to better-match the kinematics of human locomotion would lead to more efficient and powerful pedal strokes.



Barring the usual push-back from cycling's luddite luminaries, the main reason that asymmetrical rings have not been embraced by the likes of SRAM and Shimano is that their varying diameters wreak havoc on the front derailleur action. Only a safe cracker can fine tune a front mech to shift an asymmetric two or three-by crankset and, presumably, the Big Two drivetrain makers chose perfect shifting over a potential improvement in efficiency and power. One-by drivetrains and the introduction of the narrow-wide tooth profile, however, have changed that game. With no front changer to fiddle with, those barriers no longer exist. Asymmetrical chainrings are the next logical performance improvement for mountain bike drivetrains. Rotor has handed it to us on a silver platter. The promise of a wider speed range and easier, more powerful climbing - exactly what one-by riders need - would be foolish to pass up. The next innovation destined to hit the mountain bike industry has been in serial production for over 12 years. Rotor asymmetrical chainrings are not new to mountain or to road riders, nor is the concept itself, but thanks to SRAM's successful one-by drivetrain revolution, their time has come. Before all you old-timers stop reading and begin crying out loud about the ill-fated Shimano Bio-Pace chainrings back in the 1980s, take the time to read a little farther down the page. For about a decade, asymmetrical chainrings have been winning major races under cycling's greatest names. Like Schwalbe tires among downhill racers, Rotor and its closest competitor, Osymetric, asymmetrical sprockets have been one of the most commonly blacked out non-sponsored components on ProTour road racing bikes and it is estimated by some that they are used by 40-percent of the riders. Many champion Triathlon and World Cup XC racers uses them as well. Rotor has done its homework, and its claims of increases in power output of almost seven percent are also supported by Osymetric - and by experienced pros who live by their power meters.Modern asymmetrical rings are designed like cams, with specific diameter variations designed to match the leverage rate and muscular efficiency of the human leg as it pushes the pedal around the crank's axis. While cycling's oral historians have preached that we all should be pedaling perfect circles, the concept is laughable. Sure, we have taught ourselves to pedal round chainrings with legs that were intended for walking and running, but step outside the narrow confines of traditional cycle-thought and it doesn't take a bio-mechanical scientist to understand that modifying the leverage rates of the pedal circle to better-match the kinematics of human locomotion would lead to more efficient and powerful pedal strokes.Barring the usual push-back from cycling's luddite luminaries, the main reason that asymmetrical rings have not been embraced by the likes of SRAM and Shimano is that their varying diameters wreak havoc on the front derailleur action. Only a safe cracker can fine tune a front mech to shift an asymmetric two or three-by crankset and, presumably, the Big Two drivetrain makers chose perfect shifting over a potential improvement in efficiency and power. One-by drivetrains and the introduction of the narrow-wide tooth profile, however, have changed that game. With no front changer to fiddle with, those barriers no longer exist. Asymmetrical chainrings are the next logical performance improvement for mountain bike drivetrains. Rotor has handed it to us on a silver platter. The promise of a wider speed range and easier, more powerful climbing - exactly what one-by riders need - would be foolish to pass up. - RC