Home » headsets » Threadless Headsets » d510a-1 THREADLESS HEADSETS D510A-1 EC34/28.6 | EC44/40 Alloy Cap/Cup Sealed Bearings 1-1/8″ to 1.5″ Tapered Head Tube Top Nut: 1-1/8″ Cup O.D.: 34/44 Crown Cone: 39.8 Height: 28.2 Technical Diagram