Skateboard bearings spin at incredibly high speeds during tricks and require special lightweight oils or dry lubricants to avoid collecting dirt. Too much lubricant actually slows bearings down, which is why many skaters prefer minimal lubrication or even remove factory grease. The bearings can reach over 20,000 RPM during certain maneuvers. Clean, properly lubricated bearings can make the difference between landing a trick or losing momentum mid-air.