Most of what the skateboarding public knows about the ABEC rating of bearings is based on some sort of folklore.
Oddly enough, the primary selling point for bearings, aside from price and pretty packaging, is their ABEC rating.
The 608 precision bearing has been a vital component of skateboarding since 1974 when Road Rider wheels hit the streets with the first known precision bearing for skateboards. The bearings used for those wheels were originally manufactured for use in vacuum cleaners, and had an ABEC 1 rating.
Today, ABEC 7s typically sell for more than ABEC 3s or ABEC 5s, and they’re in impressively high demand. But ask the average skateboarder what ABEC means, and chances are you’ll get an awkward silence.
ABEC is an acronym for Annual Bearing Engineers Committee, established almost 35 years ago, which is part of the AFMBA¿the Anti-Friction Bearing Manufacturers Association, Inc. The duty of the ABEC committee is to establish tolerances and specifications for the size and geometric accuracy of all bearings. Bearing manufacturers from all over the world send their bearings to the U.S.-based ABEC committee to be rated. Once rated, companies etch the rating onto the bearing.
The ABEC rating system uses odd numbers, ranging from 1 to 9. The higher the number, the tighter the tolerance of the bearing, and thus, the greater degree of precision. Tolerance levels tested by the committee include the following: bore diameter (the acceptable variation of the size of the inner bearing hole), parallelism (width variation), and the radial raceway runout (variations in the groove in which the balls sit).
Misconceptions about the relevance of ABEC ratings to the performance of a bearing used for skateboarding run awry. Steve Heplar is the national sales manager at Alliance Bearing Industries in Van Nuys, California, a major supplier of bearings to the skateboard industry. “It’s silly that ABEC ratings are what skaters are looking at,” he says. “An ABEC 1 or 3 is all you really need on a skateboard. In skateboarding, you’re not using the precision of the bearing.”Heplar thinks the performance of a bearing is diminished by the imprecision of the bearing-axle interface¿a 5/16-inch axle in an eight-millimeter bearing: “On a skateboard, they’re putting a smaller shaft into the bore of the bearing. It’s oversized, and the shaft is undersized¿you’re not really getting maximum use at that point.
“Today, skateboard companies are selling bearings, mainly with ABEC 1, ABEC 3, ABEC 5, and ABEC 7 ratings. The common misconception is that the higher the ABEC rating, the better and faster the bearing. This isn’t necessarily true.
“There are ABEC 1s and ABEC 3s¿which are the lower end of precision bearings, and ABEC 5s and ABEC 7s are at the higher end,” Heplar explains. “Then there are the ABEC 9s¿those would be used in a very critical high-tech application, like sending a rocket ship to the moon.”
Heplar describes the difference between an ABEC 3 and an ABEC 7 bearing as subtle, and doesn’t believe the difference will affect a skateboard bearing’s performance. “The precision or the ABEC of the bearing doesn’t really matter because skateboarding is a non-precision application,” he says. “Unless the skateboarder is going 70 miles an hour, which is rather unlikely.”
Scott Zahn is the President of Tulsa, Oklahoma-based Global Bearings and Terminator Bearings, another major distributor of bearings to the skateboard industry. “More important than ABEC ratings, skateboarders should look for the types of materials that the bearings are made of,” he says. “It’s probably the most important thing. There are really four different components to a bearing: the balls, the inner and outer raceways, the retainer, and the seal or shield that goes on the bearing. For each of those components, there’s a wide range of materials that can be used.
“The best components for the balls and the raceways iis 52¿100 chromium steel. There are quite a few different options in types of steel used, but for skateboarding, it’s the most durable and the highest performance option.”
For most industrial uses, the load put on a bearing is a radial load¿the forward and backward spinning motion. Radial loads are typical of a bearing that is only turning in one direction, as in an electric motor or a machine tool. For these functions, a high level of precision is required because the bearings turn at incredible speeds in one direction. Hence, ABEC measurements must be made to an extremely tight tolerance¿a thousandth of an inch, or a hundredth of a millimeter. Even skateboarding’s superheroes can’t spin wheels fast enough for the ABEC rating to play a significant role in enhancing their performance.
Significantly, the ABEC committee doesn’t test for axial¿or side loads. Skateboarding exerts tremendous axial loads on bearings when skaters slide sideways or boards land on their rails, flexing the wheels over the bearings. Bearing components can deform or be damaged by heavy or repeated axial loads, particularly if they are manufactured to a high tolerance.
In the early 1980s, George Powell realized that skateboarding did traditionally unconventional things to bearings. Powell, who has a background in engineering, began to experiment with various bearing designs for skateboarding. The Powell Swiss bearings were the first bearings designed specifically for skateboards. Powell recognized that bearings used in skateboarding should be designed with axial loads in mind, and that unlike bearings made for electric motors, skateboard bearings don’t have to spin quite as fast. Machine bearings are typically packed with thick grease, which ensures a long life but is sluggish at low temperatures. For his skateboard bearing, Powell began using a lighter lubricant that was less resistant and retained far less dirt than heavier greases, and synthetic ball retainers instead of metal retainers that are more easily damaged from axial loads.
And most skateboarders can attest to the fact that skating with dirty bearings can be a bit dodgy.
Today most bearings marketed for skateboarding use light oil lubricants, and many feature synthetic retainers. Some companies have offered other alternatives to the standard 608 bearing¿Ninja is promoting its small 688 Mini-Miser, and Reflex recently introduced its large-bore Anti-Lock Bearing System. But the tried-and-true 608 has proven itself through nearly three decades of skateboarding’s evolution. Despite some confusion over ABEC ratings, chances are we’ll be rolling on 608s for years to come.