FSA No. 55R ICR Headset

The No. 55R headset from FSA for the FSA Internal Cable Routing System with concealed cable routing for tapered head tubes, featuring a fully integrated bearing housing with a 52 mm internal diameter at the top and a semi-integrated bearing housing with a 66 mm internal diameter at the bottom, as well as a 1 1/8 inch to 1.8 inch tapered fork steerer. The upper cap, featuring a large recess and two guide grooves, is compatible with the FSA Internal Cable Routing System.

FSA No. 55R ICR headset technology and dimensions:

• Top: IS52/28.6 fully integrated, for 1 1/8-inch steerer tube
• Bottom: ZS66/46 semi-integrated, for 1.8-inch steerer tube
• Top stack height: 10.5 mm
• Bottom height: 2.4 mm
• Slotted fork cone for easy installation
• Weight 102.8 grams (manufacturer’s specification)

Top bearing installation dimension IS 52-28.6 mm:

Head sets with Integrated Standard (IS) require frames that incorporate the raceway for the head set bearings; this is why they are also referred to as fully integrated. The headset then consists of the bearings, which are inserted into the head tube of the frame, the fork cone and the upper bearing cover with cap and retainer. Upper frame mount 1.5 inches / 52 mm diameter, bearing angle 36x45 degrees, upper steerer tube diameter 1 1/8 inches / 28.6 mm.

Bottom bearing installation dimension ZS 66/46 mm:

Zero Stack refers to the bearing cups that are fitted into the frame without any lateral protrusion. ZS headsets require frames with a reinforced head tube, as the bearing cups are relatively short and the frame would otherwise be unable to absorb the forces involved. Lower frame mount 1.8 inches / 60 mm diameter, bearing angle 36x45 degrees, lower steerer tube diameter 66 mm, 1.8 inches. The tapered seat is 46 mm.

Herstellerinformation: FSA – FULL SPEED AHEAD Europe, Via del Lavoro, 56, 20874 Busnago (MB), Italy, https://www.fullspeedahead.com