SRAM's XX1 GXP Direct Mount Crankset achieves a low 156 Q-factor by taking advantage of two of the crank's essential design characteristics: spider-free mounting and a single chainring. The result places the pedals over a centimeter closer to the bottom bracket than they'd be on a 168. Though that may not seem like much in the vacuum of a tech spec sheet, that centimeter can feel like miles when the extra clearance provides a bit more room for error on the ragged edge.
Except for the narrower profile, this crankset features the same lightweight, carbon stiffness of the wider model. The standard XX1 chainring-to-chain redesign returns unchanged, featuring a pattern of wide/narrow teeth with tall, square edges to maintain early, confident engagement for popping up rocky climbs or dropping the hammer in a finale. The direct mount version also affords the option of quickly subbing different sizes of rings for different shapes of terrain, giving the true all-mountain racer a bit of start-line flexibility to adapt to a given course, and SRAM's GXP design uses a 22mm gutter on the non-drive side to reduce friction and weight without sacrificing the drive side's power transfer.