If you're building up a frame with a 44mm head tube that needs external cups — think a lot of steel and titanium customs, plus some older aluminum and carbon frames — this is the lower half that completes the picture. The Ritchey WCS Lower Headset in the EC44/40 spec presses into a 44mm head tube and accepts a 1.5" fork crown race, which is the standard tapered-steerer interface on the lower side. It's a straightforward replacement when the original bearing has gotten notchy, or a sensible build-kit choice when you're specing a new frame from the ground up.

The bearing is a sealed cartridge with a 45° by 45° angular contact geometry, which is the right setup for a headset — it handles both the radial load from steering and the axial load from your body weight pressing down through the stem. The bearing race carries a titanium coating for corrosion resistance, which is the kind of thing you appreciate two winters in when you pull the fork and the bearing still spins clean instead of crunching like a coffee grinder.

S.H.I.S. designation here is EC44/40, meaning external cup, 44mm head tube insertion diameter, 40mm crown race seat. That 40mm crown race is the standard size for a 1.5" lower bearing on a tapered steerer, so this pairs with any tapered fork that uses a 1.5" lower. Stack height is 14.3mm, so if you're calculating your front-end stack budget for a build, that's the number to plug in. Worth confirming your frame is actually spec'd for an external cup on the lower — some 44mm frames use ZS (zero stack) or IS (integrated) lowers, and those need a different headset entirely.... Read More