The Shimano DXR MX71 race cranks are an evolution of the popular Shimano Hollowtec II cranks featuring the same lightweight, yet incredibly stiff, aluminum arms with steel pedal boss inserts and a redesigned 4-bolt spider gear to further reduce weight. The 24mm hollow chromoly spindle comes pressed to the drive-side arm for increased strength, while the included external Euro BB helps extended bearing life and increases rigidity by allowing the use of oversized bearings.