The R408 bearing is an essential reference in the world of bicycle and MTB headset bearings. With its precise dimensions of 30.1 x 41 x 6.5 mm and contact angles of 45°/45°, this sealed cartridge bearing guarantees smooth, durable and reliable steering for all types of riding, from urban cycling to demanding MTB.

Technical Summary

The R408 bearing is an angular contact cartridge bearing designed specifically for headsets fitted to 1"1/8 (28.6 mm) steerer forks. Its standardized dimensions (internal diameter 30.1-30.15 mm, external diameter 41 mm, height 6.5 mm) and symmetrical contact angles of 45°/45° make it a universal replacement part compatible with a wide range of frames and headsets according to SHIS standards: semi-integrated ZS44, external EC34 and integrated IS41.

Technical Highlights

• High-quality chrome steel construction: The chromium steel material ensures high load capacity and exceptional resistance to repeated mechanical stress during riding.
• Black Oxide anti-corrosion coating: The black oxide treatment significantly improves resistance to moisture and corrosive agents, extending the bearing's lifespan even in harsh conditions.
• Quad seal: The four-seal system (quad sealed) effectively protects the balls and internal grease against water, mud and dust infiltration, ensuring smooth operation over time.
• 45°/45° contact angles: This symmetrical geometry optimally distributes axial and radial loads, ensuring stability and steering precision in all riding conditions.

Compatibility and SHIS Standards

The R408 bearing integrates into standardized headset systems according to the SHIS standard (Standardized Headset Identification System). It is compatible with:

• ZS44 (Zero Stack / Semi-integrated): For frames with 44 mm head tube and cups partially integrated into the tube.
• EC34 (External Cup / External): For traditional external headsets with visible 34 mm cups.
• IS41 (Integrated System / Integrated): For frames where bearings fit directly into machined recesses integrated into the frame (41 mm internal diameter).

This versatility makes it a reference choice for replacing or upgrading original bearings on brands such as Cane Creek, Ritchey, FSA, Stronglight, Acros and many others.

Applications and Use

This bearing mounts in the upper or lower part of headsets for 1"1/8 straight steerer forks. It is perfectly suited to:

• Replacing worn bearings showing play, roughness or stiff steering
• Upgrading to higher quality bearings to improve smoothness and longevity
• MTB, road bike, gravel, urban bike and e-bike builds

The R408 bearing is sold individually or in pairs depending on requirements. During installation, it is recommended to apply specific bicycle grease to avoid premature friction and optimize service life.

Equivalent References

The R408 is also known by the designations PT-R408 and MH-P03 depending on the manufacturer. These interchangeable references facilitate identification when replacing your headset bearings.