This Q&A section has general information pertaining to bearings. If you are looking for model specific bearing information, check the Q&A for your model of interest. There are several Q&A sections and you will find an index of them at Q&A Central.

The parts to a bearing are, the outer ring, the inner ring, the cage which holds the balls and the shield if it is a shielded bearing.

There are many types of bearings, with these being the most common.
1 Open - the cheapest and most plentiful on the market
2 Metal Shielded - has a metal shield to keep debris out
3 Rubber Sealed - has a rubber shield to keep debris out

They have no shields or seals to keep debris out and lubricant in. They spin more freely when they are clean, but as they get dirty, performance suffers.

These have a metal shield attached to the outside ring which does not rub the outer race or the balls. They spin more freely than rubber sealed bearings and offer a good balance between maintenance and performance.

A rubber seal touches the inner and outer race and the balls as well on some bearings. Best seal, but slowest.

There are two purposes, to keep debris out and lubricant in. The different seal types trade sealing ability for performance. The rubber seal, for example, is the slowest bearing because the rubber is in contact with the rotating bearing surfaces. The open is the fastest because it has no seals to drag. But once an Open bearing gets dirty, its performance will decrease greatly.

There is quite a bit of performance difference in the 3 most common bearing types as shown in the chart below. This chart assumes that all the bearings are clean. So if you take your Open bearings and let them get dirty, then you lose all of the performance benefit of running them in the first place.

The metal shielded gives you very good performance with low maintenance and are the best choice in most cases. So these bearings earn our overall recommendation.

We spoke to a dozen bearing makers and not one had the 2.5mm in open. So this is the best we could do for our humble little hobby.

They are simply bearings that use ceramic balls instead of steel balls. The process of making the ceramic balls is very precise. Ceramic bearings avoid surface bumps, irregularities and slight deformation that can be present in metal balls. The result is the most freely spinning bearing available. These are very expensive, and usually cost several times what normal bearings do. Unfortunately, many ceramic bearings are not available in the small sizes we use.

They use the same mechanical design as a metal shielded bearing, but with a closer seal that is made from a plastic material known as Polyamide. These are more expensive and also not available in the small size bearings we use.

This is a measurement of tolerances. The higher the ABEC rating the higher the tolerance. For example, ABEC-5 bearings have tighter tolerances than ABEC-3.

Some cheaper imports do not have an ABEC rating. These are very low quality bearings and should be avoided.

Vendors selling lower ABEC-1 or non ABEC bearings generally do not tell you as it reflects poorly on their product.

It depends on where you are racing, but assuming a typical indoor track with the normal amount of grit and dust, you can expect 30 minutes before performance begins to degrade.

Again, it depends on where you are racing, but assuming a typical indoor track with the normal amount of grit and dust, you can expect 3-4 hours before performance begins to degrade.

Unless you have rubber sealed bearings (which are not recommended due to excess drag) you will need to clean your bearings.

Simply spin them and if they are not turning as freely as when you installed them, it is time to clean them.

If you do not clean them the grit will wear the balls and raceways, resulting in permanent damage.

No, different manufacturers use different colors to identify their product and develop brand awareness.