#Integrated headset for road bikes with 20 mm aluminium top cup. #Combination of lightweight 6061 T6 aluminium and stainless steel. #Sealed cartridge bearings, maintenance-free. #BBB RoundHead included. #For 1.1/8″ front forks. #Top cup: ø 28.6 mm. #Fork crown: ø 30.0 mm. #Bearing: ø 41.0 x 6.5 mm x 45 degrees