Great value Deore 2-piece design chainset for 9-speed transmissions. The 2-piece design chainset features an external bottom bracket system which is a lightweight rigid design that is incredibly strong and durable. Specification & Features of Shimano Deore FC-M590 2 Piece Design Chainset 9 Speed. Lightweight and rigid steel bottom bracket axle. SG-X chainring with patented spike pins give smooth and fast gear shifts under load. Lightweight aluminium outer with steel middle and inner chainrings. We recommend that the bottom bracket is initially installed by a bike shop to ensure perfect facing and fit. Mega9 compatible. 443222T. Black. Shimano Deore FC-M590 2 Piece Design Chainset 9 Speed is perfect for:. A lightweight rigid design that is incredibly strong and durable.