Motorcycle bearings support the wheel hubs on the axles. Bearings require a certain amount of pressure, otherwise referred to as preload. The specific amount of preload determines the number of bearings that support the wheel hubs at any given time. Cone flats thread onto the axles and press bearing cones against the bearings. Adjusting bearing cone preload prolongs the life of the bearings. With proper preload, light drag should be noticed when spinning the wheels.

Wheels with quick-release levers present a challenge. Closing the lever alters the preload. Adjusting bearings on wheels that have quick-release levers may take several attempts.

Motorcycle bearings should last for years and provide you with thousands of miles of travel---but they won't last forever. In some cases they even fail completely if they haven't been maintained correctly. Part of a maintenance schedule should include replacement of wheel bearings before they fail. The procedure isn't that difficult if you have about an hour and a few small tools. Front and back wheels are similar in procedure to change bearings and only require slightly different tooling.

For the vast majority of applications (including bicycles), even so called "cheap" Chinese bearings are more than adequate if they are properly lubricated. For non-competitive riding, an automotive wheel ina bearing grease will keep your motorcycle bearings happy for thousands of miles. I suggest solvent (70% isopropyl alcohol is fine) cleaning the balls, raceways, cones, etc, drying then immediately apply the grease to all the metal surfaces inside the bearing system. Use nitrile gloves - your finger oils are bad for bearings.

motorcycle bearings should last for years and provide you with thousands of miles of travel---but they won't last forever. In some cases they even fail completely if they haven't been maintained correctly. Part of a maintenance schedule should include replacement of motorcycle bearings before they fail. The procedure isn't that difficult if you have about an hour and a few small tools. Front and back wheels are similar in procedure to change bearings and only require slightly different tooling.

An important aspect of bicycle maintenance is to grease the  motorcycle bearings. This helps to avoid costly future repairs and give you a much smoother, more comfortable ride. The motorcycle fag bearings are between the cup in the wheel hub and a cone screwed to the wheel axle.

Take the wheels off the bicycle beef before greasing the motorcycle bearings.A mixture of 50 percent white teflon bicycle grease and 50 percent green axle grease works well on  motorcycle bearings.Don't make the bearing cone too tight when screwing it back into place. "motorcycle bearings"  shouldn't have any play in them and need to roll smoothly.