If you've stripped a thread, lost a part during service, or need to reconfigure stack height on an Aethos 2 build paired with the Roval Alpinist Cockpit II, this is the kit Specialized specifies for the job. The Aethos 2 Stem Spacer and Transition Kit for Alpinist Cockpit II bundles the headset transition cover, headset spacers, and stem transition spacer the frame requires when running the integrated Alpinist II bar/stem. Every piece is frame-specific to Aethos 2 and won't cross-shop with previous-generation Aethos hardware or other Specialized platforms.

The kit covers the full stack between the upper bearing and the underside of the stem. A lower headset transition top cover adapts the Aethos 2 frame to the spacers at 6.6mm height , sitting directly on the bearing as the first piece of the transition. Three 10mm aero spacers and one 5mm aero spacer let you dial stack height in 5mm increments, and the upper stem transition spacer mates the aero spacer profile to the Alpinist II cockpit's clamping interface.

One detail worth flagging before you order: the Alpinist 2 cockpit top cap and bolt assembly is available separately under part number S254800002 . This kit covers the spacers and transition pieces only, so if you've also lost or damaged the top cap hardware, plan to grab that part at the same time. The kit is the correct replacement only for the Alpinist Cockpit II integrated bar/stem — if you're running an aftermarket round-clamp stem on an Aethos 2, Specialized offers a different transition kit for that configuration.