At Interbike this past fall, Rotor finally released its much-anticipated mountain bike cranksets and compatible ovalized chainrings. Rotor took its road-winning technology and parlayed that success into rings that work on the rough trails and surfaces that usually cause stutters in the efficiency of your power output. The QX2 is designed as the inner chainring for a standard 2-ring mountain bike drivetrain. Ovalized chainrings are essentially designed to maximize the efficiency of your pedal stroke by prolonging the power zone and minimizing dead spots. They are machined with a subtle oval shape and, with multiple mounting holes, can be "clocked" to maximize the effects for your biomechanics, pedaling style, and bike geometry. The QX2 features an ovality of 10%, which helps you accelerate better and experience smoother torque and better grip off road. Additionally, the alternating thick and thin tooth profile keeps your chain from dropping -- even in the roughest conditions. This eliminates the need for a chain guide. The Rotor QX2 Inner Chainring comes in sizes: 60-22t, 60-25t, 60-26t, 60-27t, 64-25t, 64-27t, 74-25t, 74-27t, 80-26t, and 80-27t. The ring comes in the color Black.