What are the key factors to consider when selecting bike axle bearings for optimal performance and durability?

When selecting bike axle bearings for optimal performance and durability, key factors to consider include the material of the bearings (such as ceramic or steel), the bearing size and type (such as sealed or open), the quality of the bearings, and proper maintenance and lubrication. These factors can impact the smoothness of the ride, the efficiency of power transfer, and the longevity of the bearings.