If you’re building a clean, modern cockpit with fully hidden cables, the FSA No. 55R 1.5” ACR LS is the headset that keeps everything tight, smooth, and stealthy. Designed for ACR (Aerodynamic Cable Routing) setups, it routes your lines through the headset for a truly integrated front end—without the annoying rotation stop. That means full steering range, cleaner aesthetics, and a premium feel every time you drop into a corner.

Built with angular contact bearings for smooth, durable performance and precise tracking, the No. 55R is made for frames specifically designed for ACR-style internal routing.

Key Features

• Fully integrated cable routing (ACR) for a clean, modern front-end setup

• No rotation limit for unrestricted steering

• ACR top cover for a seamless integrated finish

• Angular contact bearing (ACB) for smooth, long-lasting performance

• Specific frame required (must be compatible with ACR/internal routing)

Specs

• Headtube size: 1.5”

• Bearing spec: 36° / 45° ACB

• Head tube OD: For 55.8mm OD head tube

• Fork compatibility: 1-1/8” to 1.5” tapered fork

• Stack height: 10.9mm (10.4 + 0.5)

• Weight: 92g

* Compatibility Note: Designed to work with the State Bicycle Carbon Road Frame (2026) ACR integrated routing platform.