Surly Mr. Whirly Crank Arm Sets are sold without spider or spindle for complete customization.Build it to be the crank you want: single, double, triple or trialsOutboard-style bearings must be purchased separately; use Shimano Mtn, Race Face X Type or FSA MegaEXOChainrings, and chainring mounting bolts sold separatelyArmsets include non-drive side bearing adjust cap, drive side PTO bolt & cap, and two sets of spider mounting bolts (one short for spider mounting only, and one long for mounting spider with granny ring)Forged and machined 7075 aluminumItem SpecificationsColorBlackWeight605gIntended UseMountainChainring BCD58mmArm Length175mmCrank Intended UseMountain,Single Speed,DH/FreerideDefined ColorBlack