Since their introduction many years ago, Shimano Hollowtech cranks have been the best cranks you can put on a mountain bike. Extremely strong, remarkably lightweight, and stiffer than a straight shot of whiskey. The crankarm construction exemplifies the level of craftsmanship that's put into a Shimano crankset, utilizing a 3D hollow bonded structure to further reduce weight and increase stiffness. Chainrings are easily exchanged with the new direct-mount system and the cranks can be swapped between single and double front chainring setups.