IS52 Headset for Semi-Internal Routing Built for riders who prefer the flexibility of semi-internal (under the stem) routing, our Headsets for Semi-Internal Routing were developed for frames using an IS52 headset. These headsets are equipped with a custom seal at the cable entry ports that eliminates contamination from moisture and debris, maximizing bearing life. [FEATURES] Designed for semi-internal cable routing to allow the use of standard 1-1/8" stems and headset spacers with bikes that use an IS52 upper/lower headset and a 1-1/8" to 1.5" tapered steerer tube. Only compatible with frames designed for through-the-headset routing. Custom cable entry port seals eliminate moisture and debris contamination, maximizing bearing life. Use the compression plug that comes with your fork. Sold as a complete upper and lower IS52 Headset. Specs: TYPE: IS52, Semi-Internal Routing BEARINGS: Upper & Lower Oversize Cartridge Bearings, SUJ2 Steel, 45° x 45° Angular Contact TOP COVER: CNC-Machined Alloy, Pre-Drilled for Internal Cable Routing CROWN RACE: CNC-Machined Alloy STACK HEIGHT: 10.7mm ±1mm HEAD TUBE FIT: 52mm ID / 56mm OD BEARING OD: 51.8mm CROWN RACE BORE: 39.8mm or 30mm (steerer-dependent) STEERER: 1-1/8" to 1.5" Tapered Includes: Upper & Lower Cartridge Bearings 2x Port Hole Covers — for 1x and electronic builds running fewer than 4 routing lines Nylon Compression Ring with Cable Routing Hole Nylon + Fiber Spacer (adds clearance height for smoother rotation) Custom-Sealed Cable Entry Ports Compression Plug included Compatibility Notes: Compatible with the Carbon All-Road v2 and Carbon Road and most IS52 bicycles