Bicycle Bearings 518K

Angular Contact Bearing for Bicycle Headset Assemblies

A headset bearing has a simple job: it needs to let the handlebar turn smoothly while keeping the front end properly supported.

The 518K bicycle bearing is a single-row angular contact bearing made for bicycle headset systems. Its contact angle is available in 36° / 45°, and the bearing uses a double rubber seal to help keep dust and moisture away from the rolling parts. The standard material is GCr15 chrome bearing steel.

For bicycle component buyers, the contact angle and dimensions are worth checking before ordering. A bearing that looks similar may not fit the headset in the same way.

The 518K is used around the steering area of a bicycle, where the bearing sees both radial and axial forces as the handlebar turns.

This is different from simply putting a standard radial bearing into the same position.

The angular contact design gives the bearing a defined contact angle, while the rubber seals help keep common road dust, dirt and moisture away from the inside.

For a replacement order, it is better to check the original headset bearing and its dimensions rather than choosing a model only from the bicycle type.

When sourcing 518K in bulk, we suggest checking these points on the sample:

Bearing size - make sure it matches the headset.

Contact angle - 36° and 45° are not interchangeable in every design.

Seal fit - the rubber seal should sit evenly around the ring.

Rotation - turn the inner ring by hand and check for rough spots.

Grease fill - check that the bearing is properly lubricated.

These checks are quick and can be done before a larger production order.

If you are a bicycle brand, headset supplier or replacement-parts distributor, the 518K can be supplied with different specifications according to the project.

Possible changes include:

1. Is 518K a standard bicycle headset bearing?

518K is designed as a bicycle headset angular contact bearing. The exact fit still needs to be checked against the headset dimensions.

2. Why does the contact angle matter?

The contact angle affects how the bearing handles the forces produced during steering. If the original bearing is 36°, we would not recommend changing to 45° without checking the headset design.

3. Does 518K come with rubber seals?

Yes. The listed version uses double rubber seals (2RS).

4. Can the bearing be used on an e-bike?

It can be considered for e-bike headset assemblies, but the actual load and headset design should be checked first. An e-bike may put more weight on the front steering area than a standard bicycle.

5. How can I confirm whether my headset needs 518K?

If the old bearing is marked "518K," that is the easiest way. If there is no marking, send the bearing dimensions and a photo. We can check the structure and contact angle.

6. Can you supply bearings with our brand name?

Yes. Brand or part-number marking can be discussed for OEM orders.

7. Is the 518K suitable for outdoor riding?

The double rubber seal helps reduce the entry of dust and moisture. However, sealing does not make the bearing completely waterproof. For bikes used regularly in heavy rain, mud or wet conditions, the seal and grease specification should be considered together.

8. Can I buy a small quantity for testing?

Yes. A sample order can be arranged before moving to a larger quantity.

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