Shimano's only 11-speed Ultegra crankset offering Hollowtech hollow forged crank arms not only the bike's weight, but decreases rotating mass to aid in acceleration Hollowtech technology reduces weight without reducing the crank's strength and rigidity Outer ring's Hollowglide technology cuts down on weight yet maintains strength for better power transfer and quicker and more precise shifting Compatible with Shimano HG-EV and HG-X11 chains 43.5mm chainline / 146mm Q-factor Asymmetrical 110 BCD