Answered by Kyle R
"Bones Bearings are Skate Rated™ not ABEC rated."
Bones® Bearings are the skate industry leader and favorite choice of professional skaters, and have been since their development in 1981. Over the past years, Bones® Swiss have become legendary because of their superior speed quality, and longevity. Even though Bones Swiss are the top rated bearing in skating, we don’t give them an ABEC rating. There is a good reason for this... thank you for asking.
The ABEC rating system has been around for the last 35 years. The purpose of the ABEC committee (Annular Bearing Engineers Committee) is not to test every manufacturer’s bearings and proclaim them good or bad, but to establish dimensions, tolerances, geometry, and noise standards for bearings in an attempt to aid industrial bearing manufacturers and users in the production, comparison and selection of bearings for general applications. However, since every bearing is used in a different manner and environment, bearings should be redesigned or "customized" for special uses (like skating). The ABEC rating system is not intended to be the only criteria used for selecting bearings for use in specialized applications like skating. It is only one of the tools a bearing designer can use if it is appropriate for the application.
The ABEC rating system includes grades 1,3,5,7, and 9. The higher the ABEC rating, the tighter the tolerances are, making the bearing a more precision part. High precision and small tolerances are required for bearings to function at very high RPM, in products like high speed routers that must spin at 20 to 30,000 RPM. In an application like this, an ABEC - 7 or 9 bearing rating may be appropriate. However, a skateboard with 54mm wheels turning 20,000 RPM will be traveling about 127 MPH! Since virtually all skating is done under 30 MPH, the realistic maximum RPM your skate bearings will see is about 4700 RPM and probably 90% of skating occurs under 2000 RPM. Thus, very high precision is not required at skating speeds.
The dimensions and tolerances controlled by the ABEC standards include the diameters and widths of the raceways, their shapes to some extent and the smoothness of the running surfaces. The ABEC rating system ignores side loading, impact resistance, materials selection and grade, appropriateness of lubrication, ball retainer type, grade of ball, the clearance between the balls and the races, installation requirements, and the need for maintenance and cleaning. All these bearing design requirements are very important to the performance of your skate bearing, even though the ABEC rating says nothing about them.
From our testing of bearings and our years of experience designing bearings for skating, we know that there can be a HUGE difference between the performance of two bearings that both have the same ABEC rating. Indeed, we have found that in many cases, bearings with high ABEC ratings don’t perform as well as others with lower ABEC ratings in a skate wheel. Thus, reliance on ABEC ratings alone can lead skaters and dealers to choose a bad bearing for skating over a good bearing for skating. That is why we don’t use the ABEC rating system at all. In essence, the ABEC rating is irrelevant to the performance of a skate bearing when it is used as the sole criteria for selection.
To explain this another way, choosing an ABEC-7 or 9 bearing for skating would be like choosing an Indy car to race in the "Baja 500" because Indy cars can go fast and are of high precision. It isn’t that the Indy car isn’t a good piece of equipment, just that it is not designed for off road use and so it would quickly fail when its suspension breaks and its engine clogs with dirt.
Bones® Bearings out perform all other bearings because we went to the trouble to skate rate Bones® Swiss and Bones® REDS®, not just select an ABEC rated industrial bearing and put a customized plastic shield on it. Bones have been completely redesigned for skating from the ground up and are built to Bones® specifications that include Skate Rated™ components, lubricants, tolerances and clearances.
Bones® Bearings component parts are engineered and tested to withstand the high impacts of hard landings, the high side loads of turning, and (to the extent possible) the dirt of skate environments. As a result, Bones® roll faster and last longer than other bearings. To merely give Bones® an ABEC rating would be to ignore all the improvements we have engineered into Bones and the resulting difference between Bones and standard ABEC rated bearings. Since there is no appropriate ABEC rating that will reflect the superior quality of Bones® Bearings, we have given them their own rating, Skate Rating™, to let you know that Bones® Bearings are special and made just for skaters like you, not for electric motors."
-George A. Powell