The PRO Cartridge Headset Lower is the bottom half of a semi-integrated (Zero Stack) headset, sized ZS56/40 for frames running a 1.5" lower head tube. It pairs a double-sealed steel cartridge bearing with a precision-machined, anodised alloy cup for smooth, low-maintenance steering and long service life.

Highlights

  • Double-sealed steel cartridge bearing for durability and weather resistance
  • Precision-machined, anodised aluminium cup
  • SHIS ZS56/40 lower — 56 mm cup outer diameter, 40 mm crown race seat
  • Supplied as a complete lower service set: cup with bearing, crown race, dust/gap cap and star nut with alloy bolt

Compatibility & fit

Designed for frames with a 1.5" Zero Stack (semi-integrated) lower head tube, used with 1 1/8"–1.5" tapered forks or straight 1.5" forks. The 40 mm crown race seats on a fork with a 1.5" (39.8 mm) lower steerer base. Confirm your frame and fork are SHIS ZS56/40 before ordering, as headset sizing is frame- and fork-specific.

Covered by PRO's manufacturer warranty against defects in materials and workmanship. For any warranty claim or fitment support, return the item to Tune Cycles and our team will assist with assessment and replacement.
  • Semi-integrated (Zero Stack) lower headset assembly, SHIS ZS56/40
  • Double-sealed steel cartridge bearing for smooth, low-maintenance steering
  • Precision-machined, anodised aluminium cup
  • Complete lower set: cup with bearing, crown race, dust/gap cap and star nut with alloy bolt
  • Suited to road, gravel, cyclocross and mountain bike use
BrandPRO
TypeSemi-integrated (Zero Stack) lower headset
SHIS sizeZS56/40
Cup outer diameter56 mm
Crown race seat40 mm (1.5" fork base)
BearingDouble-sealed steel cartridge bearing
Cup materialAnodised aluminium
Fork compatibility1 1/8"–1.5" tapered or 1.5" straight
IncludedLower cup with bearing, crown race, dust/gap cap, star nut with alloy bolt
SKU SHM-PRHS0060
Barcode # 8717009332699
Brand PRO