Bearings affect a skateboard by determining how smoothly and quickly the wheels spin. High-quality bearings reduce friction, allowing for faster speeds and smoother rides, while low-quality or worn bearings can cause slower speeds and rougher rides.

Skateboards typically use 608 bearings, which are standard-sized bearings with dimensions of 22mm outer diameter, 7mm inner diameter, and 7mm width. They are usually steel or ceramic and come in different ABEC ratings, indicating precision and performance levels.

To tell if skateboard bearings are good, check for the following signs:

1. Smooth Spin: Spin the wheels by hand; good bearings will spin smoothly and for a longer time without wobbling.
2. No Noise: Good bearings are quiet. Grinding or rattling noises indicate wear or dirt inside.
3. Free Movement: The wheels should roll freely when you push the skateboard. If they feel sluggish, the bearings might need cleaning or replacement.
4. No Rust or Dirt: Visually inspect for rust, dirt, or damage. Clean bearings last longer and perform better.

Yes, skateboard bearings need lubrication to perform well. Oil or lubricant reduces friction and helps keep the bearings running smoothly. However, use only lubricants designed for skateboard bearings, as some oils can attract dirt or gum up the bearings

To test skateboard bearings:

1. Spin Test: Spin the wheel by hand. Good bearings will spin smoothly and for a longer time.
2. Noise Check: Listen for any grinding or rattling noises. Quiet bearings are typically in better condition.
3. Visual Inspection: Look for rust, dirt, or damage. Clean bearings should be free of debris.
4. Feel Test: Check for smooth, even motion when turning the wheel by hand. Any resistance or roughness indicates potential issues.