The 411 By Ben Curtis
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A kid and his dad walk into a skateboard shop to buy bearings, and the dad asks the shop employee, “What is the difference between all these bearings?” This is a serious question that nearly all shop employees fail to answer thoroughly and accurately. How would you answer? Would you answer this way: “Well… there are ABEC-rated bearings, Swiss bearings, ceramic bearings … ”
OK, that answer is technically correct; but is it enough? Can you accurately explain the differences
between bearings, or what makes ABEC-rated, Swiss or ceramic bearings better than others — or not? Being able to answer any and all questions customers ask is vital for any business to survive, compete and grow.
People take their issues to the experts that know how to take care of them. Are you and the other employees at your shop experts in skateboard equipment and how it’s used? Are all the employees at your shop capable of taking care of your customers’ needs? The following information will help give your shop what it needs to
answer your customers’ most frequent questions about skateboard bearings.
Many skateboard bearings are marketed with an “ABEC rating” of 1, 3, 5, 7 or 9. But what do these ratings mean, and do they correspond to how well a bearing works for skateboarding?
ABEC stands for Annular Bearing Engineers Committee, which was founded by the American Bearing Manufacturers Association to set standards for bearing tolerances. ABEC sets tolerances, which are only the dimensions of the
entire unit and allowable spaces between the balls and the inner ring and the outer ring (also called races). That’s all!
The ABEC scale does not rate speed, durability, axial or torsional loads, torque, steel grade, ball sphericity, materials, surface finish, raceway depth, ball size, lubrication, and on and on. ABEC strictly measures tolerances; the higher the ABEC number, the closer the tolerance.
Tolerances are crucial for proper bearing function and load handling. A bearing has to have tolerances in order to rotate. The tighter or smaller the tolerance, the more accurately a bearing will spin, because the balls have less room to move on the raceway (the groove the balls roll on).
Tighter tolerances usually equal more precision and better functionality going straight down a hill or during wide turns. However, a tighter tolerance or higher ABEC rating does not presume the bearing is faster. It only implies that a bearing may function more efficiently at higher speeds. You still have to factor in axial and torsional loads, torque, material grade, ball sphericity, surface finish, raceway depth, ball size and lubrication.
So if the ABEC rating only measures tolerances but not all these other factors, what is the point of ABEC rating for skateboarding when there are so many other vital factors to consider? And can an ABEC 3 bearing actually function better than an ABEC 7?
Of course it can. The ABEC scale was not created with skateboarding in mind, and it does not account for all
the abuse skateboarders give bearings. In skateboarding, tolerances need to be adjusted differently in order to handle the axial and torsional loads that skaters vigorously apply. Thus, a bearing with a lower ABEC rating may actually perform better for skateboarding than one with a higher ABEC rating.
Unfortunately, many of the bearings in today’s skateboards were not created for skateboarding. They evolved from the early days when roller skate wheels were used on the first skateboards. However, since then, enormous improvements have been made in the quality of bearings. Plus, with some manufacturers redesigning bearings
that are skateboard-specific, we’re still evolving toward better equipment.
It’s important to account for bearing loads – vertical, axial, and torsional loads. These loads are directional forces applied to the bearing. Basically, vertical is up and down, axial is side to side, and torsional is a curve or twist.
One might assume, since bearings are placed vertically in a wheel, that bearings don’t have axial or torsional loads. Actually, bearings encounter tremendous axial and torsional loads, especially in longboarding. Imagine the amount of force applied to a bearing while speeding around a turn. Add in slides and drifts, and you have a heavy dose of axial and torsional loads.
To find out how or if bearings can handle these loads, we have to look at the raceways – the grooved tracks the balls roll on. Not every brand or ABEC rating has the same size raceway. This is where the depth and curvature of raceways prove to be important.
A shallow raceway allows less surface contact on the balls, thus providing less friction – theoretically a faster bearing. However, we must raise this question: When the balls are in a shallow raceway, what happens when bearings go into a turn? The axial (sideways) loads are causing the balls to roll away from the center of the raceway. They are now turning on the edge of the raceway.
What happens to the balls hitting the edge of the raceway? The edge of the raceway is rubbing against that ball and burnishing the ball. Burnishing is contact surfaces causing plastic deformation from sliding one object over another. In other words, this means the balls and races can gouge, scratch, and indent each other
in a circular pattern.
A deep groove raceway holds the balls securely, in alignment, during axial and torsional loads. A deep raceway does not translate to more friction due to extra contact surface for the balls, and it doesn’t necessarily make it a slower bearing either. No matter where the ball moves within the raceway the ball’s footprint remains the same. Once again, you have to account for other factors, such as surface finish, material hardness, and steel grade. Skaters could make a more educated choice of bearings if more manufacturers disclosed this information.
Some brands have made an effort to steer clear from marking an ABEC rating on their packaging. Oust uses what they call a MOC (Machined Optimum Clearance) rating, and Bones Bearings created their own Skate Rated™ scale, which they say reflects their efforts to design and construct their bearings to specifically handle the rigors of skateboarding. Although this is a leap in the right direction for skateboard bearings, it does not automatically give the consumer an understanding of what makes them any better. I urge you to contact the various bearing companies and ask specifically what they have done to create better bearings as relates to skate ratings.
Core shops need to represent themselves as being more knowledgeable about what is really going on with skateboard products. But being knowledgeable is just the beginning. What else can you provide your shop that differentiates it from all other retailers?
Deep product knowledge can help foster the soul and true skateboarding culture to your shop in ways no one else has accomplished. You can be the expert “doctor” in your skate shop. AXS