IS52/30 Conversion Bottom fits 1-1/8" straight steerer tubes to tapered 52mm 1.5" IS bottom head-tubes * Integrated (IS) assemblies feature chamfers molded inside the head-tube with no press-in cups * Bottom assemblies include bottom cup, sealed oxide bearing, and crown race * Consistent stack heights across 10, 40 and 110 Series * Internal parts are cross-compatible across 10, 40 and 110 series