The Shimano Deore M612 Triple 40/30/22 10-Speed Chainset is a 2-piece design chainset features an external bottom bracket system which is a lightweight rigid design that is incredibly strong and durable. The SG-X chainring with patented spike pins give smooth and fast gear shifts under load. The outer chainring is made from a lightweight aluminium, with the middle steel/glass fibre middle and a steel inner chainrings. The lightweight and rigid steel bottom bracket axle is designed to fit HollowTech II bottom brackets. The Deore M612 chainset is great valve and give you many years of service.