INTERNAL CABLE ROUTING HEADSET C522A-1 IS52/28.6 I IS52/40 Alloy, Sealed Bearings 1-1/8″ to 1.5″ Tapered Steerer Top Nut: 1-1/8″ Bearing O.D.: 51.8 Crown Cone: 39.8 Height: 11.5 Weight: 138g Technical Diagram