Comparing Ball Bearings and Roller Bearings
The most common types of bearings you’ll find in a motorcycle are ball bearings and roller bearings.

Ball bearings use spherical balls in between the inner and outer rings to reduce friction. The contact points between the balls and the rings are very small which allows the bearing to spin freely at high RPMs.

Roller bearings use small cylindrical rollers instead of spherical balls to allow the inner and outer rings to spin freely. Using rollers helps spread the weight of heavier loads across a larger surface.

Axial vs. Radial Loads
It’s helpful to understand the two types of loads a bearing will be subjected to during its operation, namely axial loads and radial loads.