All About Bearings
Bearings probably have the most lore of inaccurate and false information than any other piece of skateboard equipment. As skaters, we are surrounded by ABEC rated, Swiss, and ceramic bearings and it's astounding how little we truly know about them. What are the best bearings? If you have an answer, how accurate are you? Here we lay to rest all the fallacies and incorrect jargon spread about the skate world for decades.
ABEC Rating and Tolerances
ABEC
The Annular Bearing Engineering Committee was created 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 and torsional loads, torque, steel grade, ball sphericity, materials, surface finish, raceway depth, ball size, lubrication, and on and on. ABEC strictly measures tolerances. If ABEC only measures tolerances and does not rate all these other factors, can an ABEC 3 bearing actually function better than an ABEC 7? Of course it can.
Now, if ABEC just measures tolerances and gives a bearing a rating based on where it falls on the scale, what is the point of ABEC when there are so many other vital factors to consider? ABEC tolerance measurements are guidelines to follow for the manufacturing of precision bearings.
Tolerances
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 accurate a bearing will spin. The reason is that 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 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.
Because of these additional factors, a lower ABEC bearing may actually operate better than a higher ABEC rated bearing. This is particularly true for street and park skating.
When the ABEC scale was developed by the American Bearing Manufacturers Association, they did not create it with skateboarding in mind, nor did they account for all the abuse skateboarders give bearings.
Tolerances are important, however, the tolerances set in the ABEC scale are not necessarily the most beneficial when it comes to skateboarding, which is why ABEC tolerances do not apply for skateboard bearings. In skateboarding, tolerances need to be adjusted differently in order to handle the axial and torsional loads that skaters vigorously apply.
Skateboard-Specific Ratings
Skateboard-specific ratings are used by bearing brands, such as Oust (Tensor) and Bones, and steer clear of an ABEC rating on their packaging. Oust uses a MOC (Machine Optimum Clearance) rating and Bones uses their own Skate Rated™. These companies have stepped outside the ABEC scale and designed and constructed 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.
If you were to visit OustBearings.com or BonesBearings.com you will find little information about what they changed to their bearings.
Unfortunately, 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 manufacturers redesigning bearings that are skateboard-specific, we're still evolving toward better equipment.
Bearing Loads
Axial and Torsional Loads
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. These are the deep groove tracks the balls roll on. Not every brand or ABEC rating has the same size raceway. This is where tolerances and raceways prove to be of utmost importance. Take a very close look at the image of raceways side by side. You will notice that each raceway is either wider or deeper than another.
A shallow raceway allows less surface contact on the balls, thus providing less friction, theoretically a faster bearing. Although now, we must raise this question: What happens when bearings go into a turn, and the balls are in a shallow raceway? The loads applied are causing the balls to roll away from the center of the raceway. They are now turning on the edge of the raceway.
While the balls are hitting the edge, 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. Tighter tolerances reduce the chances of balls burnishing by keeping them in the raceway more. This is why bearings with tighter tolerances function better at greater speeds.
Raceways
A deep groove raceway holds the balls securely, in alignment, during axial and torsional loads. A deep raceway does nottranslate 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 manufacturers disclosed this information.
The degree in which a polished finish is applied to the balls and raceways will relate to the steel strength and hardness. It is presumed that these results are caused by cold working of the steel during polishing. In other words the surfaces are getting flatter and smoother creating a very hard mirror surface. Take another look at the raceways and see the differences in the polish surfaces.
Bearing Spacers
In street-style skating compared to longboarding, bearing spacers are rarely 
used. A lot of brands do not supply bearing spacers inside each pack, also the majority of street skaters don't use them or know what they are for.
Bearing spacers dramatically reduce axial and torsional loads on the bearings inside the wheel assembly. Because the center space or hub of the wheel is hollow the inner race has space to move when loads are applied. By providing a spacer, the 2 inner bearing races inside the wheel can be linked together as 1 unit and not move on the axle. This allows the axle nut to be tightened all they way down. When this is done the bearings can properly be seated and function more optimally.
Swiss
With more skaters hearing that ABEC does not apply to skateboarding, is there no surprise that more brands are currently promoting "Swiss" bearings? What is a Swiss bearing and why are they claimed to be better than all other bearings? Would your first response be "They are manufactured in Switzerland", or "They're made from Swiss steel"?
We can look at product packaging or the bearing itself to investigate. Is there a country of origin label stating, "Made In Switzerland", or "Swiss Made"?
Some manufacturers may label a bearing Swiss Made when they are merely produced on a Swiss screw machine, which definitely does not denote Swiss-made. Too see a Swiss screw machine in action check out the video below.
What differentiates Swiss bearings to make them better, and how does the quality compare to American or Chinese bearings? As consumers, have we been duped for decades into the misconception that the Swiss make superior products?
Other than materials used and country of origin, there are no noticeable physical, mechanical, or material contrasts that constitute a bearing to be Swiss or superior. These are not watches, army knives, or cheese here. 
We all know what Swiss cheese looks and tastes like and that it can never be called cheddar cheese. Swiss bearings do not haveany attributes that separate them from any bearing manufactured around the world.
When comparing a Swiss bearing to a Chinese bearing there relatively is no difference. A bearing is a bearing, is a bearing. Swiss, in a way, is thought of as a category or rating above ABEC. Swiss is merely a country who makes bearings like everyone else.
Besides, why should we assume that bearings from Switzerland are of a higher quality than those of the United States of America, or even China for that matter? Remember, it was the AMBA that invented the ABEC scale to grade precision ball bearings not the Swiss. Also, the USA is far more recognized throughout the world for manufacturing products of the highest quality and craftsmanship than Switzerland. Example: NASA.
I urge you to contact various bearing manufacturers and ask them specifically what is a Swiss bearing and why are they better than all other bearings. Or is it all marketing hype?
With this in mind, let's take a look into what makes ceramic bearings "simply the best".
Ceramic vs Steel
Perhaps, it's your understanding that ceramic bearings are superior to ABEC 9 and Swiss Bearings... and what about "Swiss ceramic" bearings?
There are 3 common ceramics used in ball bearings:
- Silicon Nitride
- Zirconium Dioxide
- Silicon Carbide
Silicon Nitride
Silicon Nitride ceramic is the hardest of the three and most often used in ceramic hybrid bearings. It's important to keep in mind that "ceramic" only refers to the balls. The races remain stainless steel, hence hybrid. Ceramics are not harder than most steel balls, although the marketing headlines claim them to be. Ceramic is brittle and does not handle vertical loads the way steel can, which could make their use in skateboarding seem somewhat impractical, however, the real test of a bearing is in its performance.
In Rat Vision's testing of ball bearing strength, a PHI laboratory press, model P210H-X1824, was used. Ceramic and steel bearings were tested for compression strength. The types of bearings tested are as follows:
1. Ceramic bearings: The ceramic bearings tested were the top-of-the-line product from a very well-known bearing manufacturer located in the USA.
2. Three separate brands of steel bearings, made in China, which are sold by American companies and found in most skate shops.
3. One steel bearing product manufactured in the USA.
The results are shown in pounds of compression:
"Top of the line" ceramic bearing shattered at ......................................8800
"Swiss made" steel bearing made in China split at .............................7200
The most popular steel bearing made in China failed at ...................7800
A semi-popular steel bearing made in China failed at .......................7700
The American made steel bearing failed at ......................................22,000
Rat Vision's findings show the steel bearings manufactured in the USA are far and away the strongest of the bearings tested. We should note that perhaps not all American made bearings will fail at around 22,000lbs. Our test proves that Swiss made and ceramic balls are not superior than steel.
Steel
Steel is ductile and has elasticity that enables it to retain its original shape after loads are applied. The one advantage ceramic has over steel is resistance to corrosion, meaning rust. But, remember ceramic bearings are hybrids; therefore the inner and outer rings are susceptible to corrosion. Applications exist that specifically require ceramic bearings, but skateboarding is just not one of them.
Maintenance
Rubber Seals and Metal Shields
Before we get into cleaning and lubricating, we need to realize the consequences of not having shields or seals covering the sides of bearings. Seals and shields provide on going maintenance by protecting them from contaminants and keeping lubricants in. They aren't called seals and shields for nothing. We do not recommend following any trend that removes seals and shields.
There are 3 different types of bearing covers:
1. Removable rubber seals
2. Non-removable metal shields
3. Removable metal shields held in by a C-ring/clip.
Metal shields and rubber seals dramatically increase bearing life and extend optimum performance. They help keep lubricants in and contaminants out. Once a bearing is exposed, its useful life will soon come to an end.
So, why are the majority of bearings sold with only one shield or seal? Sound like a dumb idea? It is.
One shield is like having half a raincoat. It leaves an opening on the side of each bearing that faces the inside of the wheel assembly. Keep in mind, there's space between the truck axle and the bearings, because they don't fit together tightly enough. This space allows contaminants to enter inside the wheel assembly. Once inside the wheel assembly, if seals are not there to protect the bearings, contaminants will foul the bearings.
This also means lubricants that allow proper functionality spill onto the axle. We should also note that a minimal amount of contaminants and lubricant can get into or out of a bearing between a shield or seal and the inner ring.
Why don't bearings and axles fit tightly together? It's because manufacturers of trucks and manufacturers of bearings don't use exact standards of precise measurement to create a tight fit. And, why not? It's so there's no difficulty putting one company's bearings on another company's axles. The typical fit is fairly loose.
Bearing "Hiss"
It's often said that breaking in a bearing is when it starts to make that cool "hissing" sound. A lot of skaters believe this fallacy. The hissing caused by vibrations from metal-on-metal contact creates that illusion when rolling a wheel off the ground. When there is nothing slowing a bearing down, like lubricants or contaminants, it might make the hissing sound and roll fast. However, riding on bearings in this condition causes high friction, corrosion, rust, slow performance, and a trip back to the shop for a new set of bearings.
Breaking Bearings In
Breaking bearings in means that after a certain number of hours the balls have created tiny grooves and changed the condition of the contact surface in the raceway. Once this has occurred, the bearings will roll noticeably faster and function at their intended optimum performance. The length of time depends on the steel and surface finish of the balls and races, roughly 10-20 hours, which means maintaining bearings during this waiting period is crucial in order to reach peak performance.
Cleaning
Orange Oil vs Dangerous Solvents
Because of the exposure and abuse bearings undergo in skateboarding, they are often the first items needing replacement. When a bearing is not spinning, having trouble spinning, or looks and sounds like its corroded, it is best to replace it. All the cleaning and lubricating in the world will not renew a damaged bearing.
This is why cleaning with mineral spirits, gasoline, acetone, turpentine, butane, rubbing alcohol, paint thinner, kerosene, and bleach are not going to do the job. Most importantly screwing around with dangerous chemicals to clean bearings is unnecessary. If bearings are properly maintained, no one, not even a pro skater, needs to resort to harsh chemicals.
A safe and totally effective cleaner is citrus cleaner. Usually found in a spray bottle at most drug and hardware stores, citris cleaners are made from orange oils that is not a dangerous chemical.
Orange oil is an organic hydrocarbon compound called terpene, consisting of about 95% d-limonene. This hydrocarbon is used as an industrial solvent and works wonders on oils, dirt, and grime.
Cleaning Steps
Using a bearing cleaning kit, a kid can clean his bearings safely and effectively with hardly any mess or danger. Also, the majority of citrus cleaners contain no harmful chemicals. In most cases, citrus cleaner is just water, surfactants (emulsifiers), and orange oil. Although, because d-limonene dissolves oils, it could possibly irritate the skin.
After cleaning bearings with citrus cleaner, the cleaner needs to be removed. The best method is to run the bearings under hot water. Say what? Yes, although this may seem to be against conventional wisdom, it will not hurt bearings in the slightest if the moisture is quickly removed with a hair dryer.
After blow-drying, the bearings will be clean and dry and make that adorable hissing sound. The next step is lubricanting. Reports circulate about all kinds of lubricants being used from cooking oil, hair clipper oil, to even trumpet valve oil. It's best to stick with thin oils that are strictly made for lubricating small moving parts, such as electronic or sewing machine oil.
For instructions on how to make your own bearings cleaning kit click here.
Lubricants
Thin oil is key to unlocking the speed in bearings. Thick oils will slow bearings way down, but will remain in the bearing a little longer. This does not mean to use thin penetrants such as WD-40 and similar products to get more speed out of your bearings.
Lubricants designed for small moving parts like sewing machines work great. Thin lubricants made for speed require more applications as they run out of the bearing easier than slightly thicker oils. Thicker oils, with the consistency of cooking oils, are better for skaters who are not into speed and who don't want to frequently service their bearings.
WD-40
WD-40 and similar products are more solvents than lubricants. They are thin to enable them to get into tiny crevices and have minimal lubricants to free rusty, stuck parts. However, WD-40 should not be used for rusty bearings, because even moderately rusted bearings are already damaged beyond repair.
Cleaners that also contain lubricants contradict their purpose and value. You have a solvent trying to dissolve the oils that are meant to lubricate. Class action lawsuits occur from ridiculous products like these that waste the consumer's money.
When to Clean or Lubricate
For avid skaters, checking lubricants every 2-3 weeks is a good rule of thumb. Cleaning bearings may need to be done every 3-4 weeks. For those who skate about 1-2 days a week, you can stretch out the maintenance by adding an additional 2-3 weeks for both cleaning and lubricating.
