Choosing Skateboard Bearings
One of the purposes of bearings is to eliminate friction between the metal axle the bearings spin around and the metal inside of every wheel. Due to the axle being fixed, the bearings are essential in preventing the wheels from grinding against the metal while they spin. The bearings provide movement to your board by running a bolt through the bearings placed on each wheel.
Each bearing holds seven or eight balls that are lubricated, these balls are designed to ease tension between the heels and axle while also disperse the weight of a load. The balls are usually made of steel.
The build up of heavy friction between the axle and the wheels can cause the metal to heat up, thereby causing it to expand and make the bearings ineffective. The best way to prevent this is to keep your bearings lubricated, clean and dry, that you may get the most use out of them. It should also be noted that the quality of the steel bearings does vary from brand to brand, typically the more expensive the bearing is the higher quality tends to be.
Ceramic bearings were created when skaters recognized a need for bearings that were less affected by the heat produced by friction. Using a compound called silicon nitride they created a bearing that was not only harder than its steel counterpart but also smoother. In the end it created a bearing with far less friction and less need for lubricant. Another advantage to these ceramic bearings is that when friction does occur, the ceramic material does not expand, leaving no effect on the skateboard’s performance.
With ceramic bearings you get what you pay for. They are much more expensive steel bearing, ranging from $70-$100. But by providing a smoother ride and less friction the bearings themselves typically last a lot longer. Ceramic bearings also house more balls which increase their ability to perform. Ceramics bearings do not rust, which causes less maintenance and less replacement in general.
A standard size of bearings is 8mm core, a 7mm width, a 22mm outer diameter. They are most often referred to as “608” and they match up with almost every skate wheel on the market, which makes them the industry standard.
The American Bearing Manufacturers Association has a division referred to as the Annular Bearing Engineering Committee or ABEC who designed the standard in the bearing industry. They created a rating system to measure the amount of variation from an exact measurement in precision bearings who ratings could run from 1 to 9, using only odd numbers. The higher numbers equal more precise tolerance. However, the higher the tolerance tends to as include higher prices.
Many skate bearing manufactures still use the ABEC rating, but it should be noted that some do not. Bones Bearings in particular use their own rating system, so in the end the ABEC rating system is not the end all when considering bearings for your board.