Forged aluminium arm/spider design with an integrated (UT) Ultra-Torque, Hirth joint semi-axle bottom bracket spindle Enhanced Shifting Performance (EPS) Actuation System features two specialized sectors of the chainrings, an up-shift & a downshift section, for instantaneous shifting Light alloy 11 speed chainrings with hard anodization, corrosion-proof & wear-proof treatments. Large chainring with ramps & 8 pins, plus alloy chainring & fixing bolts