Surly's Offset Double Crankset is designed specifically for bikes running very large tires and rims, such as Surly's Moonlander and/or Pugsley. The offset helps prevent chain rub on the tire. The crank is made of forged and machined 7075 aluminum, is 9- and 10-speed compatible and comes with 22- and 36-tooth 5-bolt chainrings. A precision Enduro bearing-equipped English-thread bottom bracket is included, so this versatile crankset is ready to spin.