Headset bearings sit in the steering force path, so any roughness, play, or pitting up top translates directly into vague handling and that creak that shows up halfway through a ride. The Ritchey WCS Logic Upper Headset Assembly is the drop-in replacement for the top half of a ZS44/28.6 headset — the most common upper spec on modern road and gravel frames running a 1-1/8" steerer. You get the cup, the sealed cartridge bearing, the compression ring, and the top cap as a matched unit, which sidesteps the headache of sourcing individual pieces from different brands and hoping the tolerances play nice.

The ZS (Zero Stack) designation means the bearing sits inside the head tube rather than perched on top of it, keeping stack height down compared to external cup designs while still using a serviceable cartridge bearing you can swap when it eventually wears out. Ritchey machines the cup from aluminum and pairs it with a 45°/45° angular contact sealed cartridge bearing — the angular contact geometry handles the combined radial and axial loads steering puts through the upper bearing, and the sealed cartridge keeps grit, sweat, and bar tape adhesive out of the races.

Bearing dimensions are 41.0mm outer diameter, 30.15mm inner diameter, 7mm tall. The 44mm cup outer diameter presses into a ZS44 head tube, and the 28.6mm bore takes a standard 1-1/8" steerer with no adapters or shims required. If your current upper has gone notchy when you turn the bars, or you're building up a frameset and need a complete top-end assembly that matches what Ritchey specs on their own Road Logic and Swiss Cross frames, this is the part. Pairs with Ritchey's matching lower headset assemblies to build out a complete system sized to your frame's head tube spec.