SKU # 60623 THE 2-PIECE DESIGN CHAINSET FEATURES AN EXTERNAL BOTTOM BRACKET SYSTEM WHICH IS A LIGHTWEIGHT RIGID DESIGN THAT IS INCREDIBLY STRONG AND DURABLE 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/GLASS FIBRE COMPOSITE MIDDLE AND STEEL INNER CHAINRINGS WE RECOMMENDTHAT THE BOTTOM BRACKET IS INITIALLY INSTALLED BY A BIKE SHOP TO ENSURE PERFECT FACING AND FIT 10-SPEED DYNA-SYS COMPATIBLE 42X32X24T 175MM