The acera 9 speed 403022 mtb chainset from shimano is a great value mega 9 chainset that offers slick hyperdrive shifting performance for the off road enthusiasts the 4 arm cranks mount onto 9 speed compatible hyperdrive sg x chainrings which allow for fast and smooth gearshifts whilst on the go and have a 9664 bcd the cranks are compatible with 118mm octalink bottom brackets and come in silver only in 170mm or 175mm crank lengths