The Revolution Ceramic Series bearings are a low friction bearing with several options to help satisfy anyone's desire. What makes this bearing unique is that it has a rubber seal on one side while having a metal shield on the other. Instead of the steel balls they use silicone nitride ceramic balls (Si3N4). Rubber seals are great protectors against dirt but the price is that they offer a little more friction due to the tighter seal. Now the performance of a metal shield is excellent but allows dirt to get in easily. So with the Revolution series, you run the rubber side towards the outside and the metal towards the inside. You get the protection of the rubber but the added performance by having one less rubber seal. But you don't have to stop there, if you are truly performance oriented and want the least amount of friction then you're in luck. You can quickly pop off the rubber seal with an X-acto and place the metal shield facing outward in your hubs. This is the best performance you could attain while maintaining some protection from dirt.
10x15x4 Revolution ceramic bearing by Avid Racing Concepts can spin at higher rpms with less drag and the life of the bearing is far greater than a steel bearing but in our industry we suggest that you maintain them with oil or grease every half-gallon to a gallon for the longest life possible. Another benefit to ceramics is the weight difference in the balls allowing for less rotating mass.
