Bearing Seals & Shields
Rubber seals and metal shields are known as closures and provide an important functionality, which is to keep bearings well lubricated and protected from contaminants. There are three types of bearing closers that are featured on bearings. These closers are either rubber seals, metal shields, or non-removeable metal shields.
We do not recommend following any trend that removes seals and shields.
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 skateboard wheel assembly. Keep in mind, there's space between the skateboard 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 bearing seals are not there to protect the bearings, contaminants will foul the bearings.
This also means skateboard lubricants that allow proper functionality spill onto the truck axle. We should also note that a minimal amount of contaminants and lubricant can get into or out of a skate bearing between a shield or seal and the inner ring.
Bearing seals ans shields are an important feature. We recommend riding bearings with two closures to ensure a longer bearing life, less maintenance, and higher performance.
Why wheels can wobble
Why don't bearings and axles fit tightly together? It's because manufacturers of skateboard trucks and manufacturers of skate 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.
Is it a bearing seal or a ball retainer?
The image below is to help with any confusion between a rubber seal and a ball retainer or cage. Sometimes people try to remove the ball retainer when cleaning. Removing the bearing ball retainer is unnecessary. Only the seal or shields needs to be removed during maintenance.
Seal and shield codes
Below is a guide to inform you of the different codes seen on sheilds and seals. These codes represent the type of closure and the quantity (1 or 2).