The ZS44/28.6 is the standard Zero Stack headset bearing for frames with 44mm headtube diameter and 1-1/8" straight fork steerers. Our ceramic set covers both upper and lower positions with matching Grade 3 silicon nitride bearings, DLC-coated races, and ABEC-7 tolerances. Ideal for older-geometry road frames and many current gravel frames that retain the 1-1/8" straight standard.
What You Get
- ✓ Grade 3 Si₃N₄ ceramic balls — reduced steering friction from ride one
- ✓ DLC-coated chromium steel races for extended bearing life
- ✓ ABEC-7 precision tolerances for smooth, play-free steering
- ✓ Matched pair: upper and lower bearings included
- ✓ Direct replacement — no special tools beyond headset press
Technical Specifications
| Includes |
2 bearings |
| Seal Type |
Integrated contact seals |
| Tolerance |
ABEC-7 |
| Fork Steerer |
28.6mm (1-1/8 inch) |
| Expected Life |
20,000–35,000 miles |
| Race Material |
52100 Chromium Steel, DLC Coated |
| Bearing Material |
Grade 3 Silicon Nitride (Si₃N₄) |
| Bearing Standard |
ZS44/28.6 |
| Headtube Diameter |
44mm |
Compatibility
Frames with 44mm headtube and 1-1/8 inch straight fork steerer
Older Cannondale, Trek, Specialized road frames
Current gravel frames with straight-steerer geometry
Cyclocross frames with ZS44 headsets