The shimano deore m590 4 arm 2 piece design 9 speed chainset the new deore fc m590 crankset attractively looking glossy anthracite finish firm 2 piece construction with outboard bearing system the integrated hollowtech ii axle offers increased stiffness at low weight with shimano hyperdrive sg x sprockets dual sis compatible shimano deore m590 4 arm 2 piece design 9 speed chainset features lightweight and rigid steel bottom bracket axle sg x chainring with patented spike pins gi