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SKU: zs44zs56
Clear Options


The ZS44│ZS56 headset is designed to fit frames with tapered 44mm/56mm head tubes and works with tapered 1-1/2” fork steerers.  The “ZS” stands for “Zero Stack” as the section of the cup that houses the bearing sits inside of the frame’s head tube.  The “44/56” stands for the top/bottom diameter of the “skirt” that presses into the frame.

Note: As of 9/14/23, headsets will no longer include Star Nuts due to the Earth’s star nut overpopulation crisis. If you need one, they are available separately here.



  • U.S. sourced 6061-T6 aluminum
  • Machine engraved White Industries logos 
  • Easily replaceable Enduro bearings
  • “Split” crown race for tool-free installation and removal
  • Really sweet matching headset spacers available separately
  • Can accommodate “tapered 1-1/2” forks with a 40mm crown race seat


  • SHIS specification
    • Upper: ZS44/28.6
    • Lower: ZS56/40
  • Stack height
    • Upper: 8mm
    • Lower: 4mm
  • SHIS definitions on the Park Tools website: here
  • Frame/Fork specs:

Frame upper head tube inside diameter

43.95mm to 44mm

Frame lower head tube inside diameter

55.9mm to 55.95mm

Fork steerer diameter top section 

28.45mm to 28.6mm

Crown race seat diameter for

 “straight 1-⅛”

30.015mm to 30.075mm

Crown race seat diameter for

 “tapered 1-¼”

33.03mm to 30.09mm

Crown race seat diameter for

 “tapered 1-½”

39.79mm to 39.85mm



Headset Model

Upper Bearing (inner/outer angle) Lower Bearing 

(inner/outer angle)

Lower Fork Race Compatibility


ACB3645SS 36/45 ACB6808CCSS 36/45 1-⅛” (30mm)

 1-¼” (33mm)

 1-½” (40mm)


Additional information

Weight N/A
Dimensions N/A
Head Tube

Top Steerer

Bottom Steerer / Crown Race


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