This is a conversion headset, not a standard one: the cups are sized ZS49 for a 1.5in ZeroStack head tube, but the bearing and crown race are sized for a straight 1-1/8in steerer – so it lets a 1-1/8in fork run in a frame built for a 1.5in head tube.

Highlights

• Converts a 1.5in ZeroStack (ZS49) head tube to run a straight 1-1/8in steerer fork
• ZS49/28.6 top, ZS49/30 bottom – same ZS49 cups, 1-1/8in-sized bearing and crown race
• Sealed, black-oxide cartridge bearings top and bottom
• Steel, face-sealed crown race
• 6061 aluminium cups, 115g, black finish

What S.H.I.S. means here

S.H.I.S. (Standardized Headset Identification System) is the industry code for headset fit: the letters say the cup type (ZS = ZeroStack), the first number is the head tube's inside diameter in mm, and the number after the slash is the steerer or crown race diameter the bearing takes. This headset is ZS49/28.6 on top and ZS49/30 on the bottom – the same 49.61mm ZeroStack cups, but a 28.6mm top bearing and a 30.015mm crown race seat, both sized for a 1-1/8in steerer.

Compatibility & fit

Fits a frame with a 49.61mm ZS (ZeroStack) head tube, running a fork with a straight 1-1/8in (28.6mm) steerer. Never fit a headset by stem clamp size alone – measure the head tube and steerer, or check Cane Creek's fit guide, before ordering. The Tune workshop can confirm fit and press a headset as part of a fork or frame build.