Headtube Interface - External Cup

External Cup headsets have an upper and lower cup that are pressed into the headtube of the frame. These cups are what house the bearings which allows for smooth turning handlebars. Since the cups are visible from the outside there are many colors available on the market so you can customize the colors to suite your color scheme.

The outside diameter of the cup's flange must be the same size or within a millimeter of the inside diameter of the headtube. A headtube with a 44mm ID can only accept a 44mm OD headset cup.

External cup's can house a variety of headset bearings types including loose ball retainer and sealed cartridge bearings. Inexpensive bikes will typically have loose ball headset bearings for they're low cost while more expensive bikes will have sealed cartridge bearings which offer smoother turning and easier installation.


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