Zero Headset Bearing 40x51.9x8Mm 45/45
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ZERO Headset Bearing 40 x 51.9 x 8mm 45/45
The ZERO 40 x 51.9 x 8mm 45/45 Headset Bearing is a replacement cartridge bearing for compatible bicycle headset systems. It uses a 40mm inner diameter, 51.9mm outer diameter, 8mm height and 45°/45° contact angle, making it suitable for headset applications requiring the Ritchey-fit/ACB519H8 specification. South African bearing listings identify the equivalent as ACB519H8 / Ritchey Fit.
Key Features
- 40mm internal diameter
- 51.9mm external diameter
- 8mm bearing height
- 45°/45° contact angle
- Angular-contact cartridge bearing
- Designed for compatible bicycle headset assemblies
- Suitable as a replacement for worn or damaged headset bearings
- Equivalent to the commonly referenced ACB519H8 / Ritchey-fit specification
Specifications
| Specification | Details |
|---|---|
| Brand | ZERO |
| Product Type | Headset Bearing |
| Inner Diameter | 40mm |
| Outer Diameter | 51.9mm |
| Height | 8mm |
| Contact Angle | 45° / 45° |
| Bearing Type | Angular Contact Cartridge |
| Common Equivalent | ACB519H8 / Ritchey Fit |
| Application | Bicycle Headsets |
Compatibility
This bearing specification is used in a range of bicycle headset systems. The 40 x 51.9 x 8mm 45/45 dimensions are also sold as a Scott headset bearing, while equivalent bearings are available under other brands.
Important: Do not substitute this bearing solely because the diameter looks similar. The height and 45°/45° contact angles must also match the frame, fork and headset bearing seats.
When to Replace Your Headset Bearing
A headset bearing may need replacement if you experience:
- Rough or notchy steering
- Grinding or clicking when turning the bars
- Excessive headset play
- Stiff or inconsistent steering
- Visible corrosion or damaged seals
Replacing the bearing with the correct specification can restore smooth headset operation and precise steering.
Best suited for: bicycle workshops, headset servicing and replacement of compatible 40 x 51.9 x 8mm 45/45 headset bearings.
