Protective shields, such as rubber seals and metal shields, play a crucial role in skateboard bearings. These devices not only significantly extend the lifespan of the bearings but also help maintain their optimal performance over time. However, it is important to note that most bearings are sold with only one shield or seal, primarily to keep costs down. High-quality bearings, on the other hand, often feature two shields, which provide substantial advantages.
For bearings with a single protective shield, it is recommended to mount them so the open side faces the inside of the wheel. This practice can help protect the bearing components from dirt and corrosion, albeit to a limited extent. It is worth noting that, while the wheel itself provides some protection for the bearing components, there is still a very narrow gap between the skateboard truck axle and the bearings. This small gap can allow contaminants to enter the wheel assembly. Once contaminants infiltrate the wheel assembly, if no seals are in place to block them, the bearings can become dirty. Additionally, a minimal amount of lubricant may escape from the skateboard bearings and end up on the truck axle. Labyrinth rubber seals can help reduce this issue, although they do not eliminate it entirely.
In conclusion, to ensure greater durability for your bearings, we recommend using bearings with two shields. This choice will significantly improve the reliability and longevity of your skateboard bearings.