Home » headsets » Tapered Headsets » rk1 TAPERED HEADSETS RK1 ZS44/28.6 | ZS55/30 Alloy Cap/Cup Sealed Bearings 1-1/8″ to 1.5″ Tapered Steerer Top Nut: 1-1/8″ Cup O.D.: 44/55 Crown Cone: 30 Height: 12.5 Technical Diagram