With the Hollowtech II crank with chain guard ring, Shimano uses a wide gradation. In combination with an appropriate cassette, the high-quality XT crank is optimally equipped for any terrain. The new I-Spec II with its narrow clamp provides a tidy appearance, less weight and more space on the handlebar. One Way BleedingThe One-Way Vent is designed to quickly and easily prevent air from entering the hydraulic system.