NEB Chain Drum Bearings

NEB Chain Drum Bearing SKF6007RS1C3

Rubber Sealed Deep Groove Ball Bearings: One of the most commonly used bearings, these types are manufactured with rubber seals inserted into the outer raceway and in contact with the inner race providing protection against the ingress of moisture, dust and other foreign matter and serve to retain the pre-filled grease in the bearing
Seals can be easily removed for applications that only require 1 seal.
Benefits: Prevents moisture and dirt getting into the bearing, lubricated for life

C3 Bearings ~ A Brief Explanation

Applications like motorcycle wheels or bicycle wheels do not require C3 rated bearings.
The bore, diameter and width of C3 bearings are identical to the none C3 version.
C3 are exactly the same quality but have a different a purpose.
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C3 bearings have additional internal radial clearances to allow expansion in high speed / temperature environments.
Typically suited to hot and high speed environments ( fans, high speed motors etc)
They can feel loose until at running temperature and speed.
They are unsuitable where critical alignment is required from the onset..
Unless the bearing you are replacing specifically says C3 on it then you should not replace it with a C3 bearing.
A rule of thumb is to replace like for like, there is no advantage to a C3 bearing in place of a standard bearing.