The ZERO R425 Headset Bearing is a replacement angular-contact bearing designed for integrated and semi-integrated bicycle headset systems. With a 40mm inner diameter, 51.8mm outer diameter and 8mm bearing height, it uses a 45°/45° contact angle and is suitable for headset applications requiring this specific bearing standard. The exact dimensions and 45°/45° configuration are also independently listed for the ZERO/Genesis bearing format.
Key Features
-
40 x 51.8 x 8mm dimensions for precise headset compatibility.
-
45°/45° contact angle for compatible integrated headset assemblies.
-
Angular-contact design supports both radial and axial loads generated through the headset.
-
Replacement bearing for servicing worn, rough or loose headset bearings.
-
Compact 8mm profile suitable for frames and forks designed around this bearing specification.
-
Ideal for workshop servicing and headset maintenance.
Specifications
| Specification |
Details |
| Brand |
ZERO |
| Model / Reference |
R425 |
| Type |
Headset bearing |
| Inner Diameter |
40mm |
| Outer Diameter |
51.8mm |
| Height |
8mm |
| Contact Angle |
45° / 45° |
| Bearing Type |
Angular contact |
| Application |
Bicycle headset |
| Replacement Part |
Yes |
Compatibility
The 40 x 51.8 x 8mm 45/45 specification is used across a range of integrated headset applications. However, bearing dimensions alone do not guarantee compatibility because headset systems can differ in bearing seat geometry and contact angles.
Before installation, match the existing bearing's 40mm ID, 51.8mm OD, 8mm height and 45°/45° contact angle. For example, the same dimensional format is listed for Genesis Zero headset applications.
When to Replace Your Headset Bearing
A worn headset bearing can cause:
- Notchy or rough steering
- Play or looseness in the headset
- Grinding or clicking when turning the handlebars
- Increased resistance when steering
- Water or corrosion damage
Replacing the bearing can restore smooth steering and eliminate unwanted headset movement.
Important: The R425 designation is specific to this ZERO bearing, so it should not be substituted purely on outside dimensions. Confirm the bearing angle and dimensions against the original component before fitting.
