Q-Rings 110BCD for compact cranks based on the concept that you can pedal more efficiently if you could only take greater advantage of your maximum power effort while lessening the time spent in the dead spots of a pedal rotation. Q-Rings´ subtle but efficient 10% ovality combined with orientation factor yield an improved pedal stroke marked by performance. Choose from 5 Optimum Chainring Positions (OCP) to fine-tune your improved riding experience and go further and faster with less fatigue. Rotor Qring Inner Shimano 39T Chain Ring Features: 100% CNC-machined, 7075-T6 aluminum alloy Steel shifting pins 5 OCP points (4 points in 50/34) Designed to work with all 9, 10 and 11 speed groupsets Some cranks require specific Q-Rings Specs: Ring Position/Type Inner Drivetrain Speeds 10 Material Aluminum Drivetrain Speeds 11 Tooth Count 39 Defined Color List Black Drivetrain Speeds 9 Chainring BCD 110 Color Black