With loftier aspirations stretching into the drivetrain world, it was only a matter of time before Shimano entered the realm of 12-speed. It started with the sleek and racy 12-speed XTR group, but for those of us who remain a little more budget conscious, it didn't take long for those changes to reach into the XT level groupset. Shimano's XT FC-M8100 1x Crank Arms take the hollowcore tech you knew from years past and switches things up to an all-new application with direct-mount chainrings, a special tooth profile for improved chain retention, and 172-millimeter q-factor for quick power and comfort in the saddle. The crank arms are crafted with Hollowtech II technology, balancing stiffness, strength, and weight for superior power transfer. Hollowtech uses cold-forging technology to create a light and hollow crank arm that doesn't compromise on stiffness, enabling you to charge hard into rowdy trail sections without worries of your crankset flexing under pressure, meanwhile the light weight keeps you from getting bogged down with extra grams when you're pushing for big mile days. Should you covet flexibility from lowland laps to days of ascents that tickle five digits, you'll appreciate the new direct-mount chainring application. The drive-side arm removes for ring placement, making chainring swaps easy to execute while your crank is still on your bike. This means you can toss on a lofty 34 or 36-tooth ring for smooth rolling singletrack, or give yourself a break with a 28-tooth when climbing is the day's main goal.