shimano xt fc-m8000-b1 boost 1x crank arms black, 175mm shimano shimano's famous for its commitment to trickle-down tech and, sure enough, there's plenty top-shelf inspiration to be found in the xt fc-m8000-b1 boost 1x crank arms. obviously, they're designed to play nicely with boost 148 rear axles, with a 3mm offset chainline that keeps your links running smoothly between cassette and chainring. the more expensive xtr's hollowtech ii construction has also trickled down to xt, letting you save weight and cash, and the new 1x11 platform lets you enjoy so much gear that you'll practically be moving backwards on those steep climbs.