It’s probably safe to say that Bearings are probably the least understood item in skating equipment. Understanding ball bearings in full could require reading a long and boring textbook from the engineering department and still there would most likely be issues not fully covered. Fortunately, in skating one does not need to go into it as high tech.

Bearings are found inside the wheels of your inline skates, basically for inline skates there are 2 main different kind of ball bearings being used these days:

- standard bearings (known as 608)
- micro bearings (known as 688)

The difference is size: the 688 being the smaller, the 608 the larger. This means that 608 bearings are also the heaviest kind. However, one should not forget, that smaller bearings are used in wheels with longer spokes and hence in the end the overall weight saved is not always as dramatic as those in favour of 688 bearings would like for you to believe.

All this means also that the steel balls inside the ball bearings are bigger for a 608 than they are in a 688. Some say that 608 bearings are better at carrying side loads and this is the case when one begins skating past the very beginner level and develops an outside angle in their skating stride. Others insist that 688 bearings have better acceleration because of smaller steel balls. Then, 608 supporters will tell you that 608 bearings last longer. To make a long story short, unless you go heavily into the physics behind ball bearings, you will never know who is right or wrong. And, even if you did that, you are still likely to come out not knowing which type of ball bearing is really best in all situations. It is mainly down to personal preference.

608 bearings are assigned a quality using the acronym ABEC (Annular Bearing Engineers Committee) and a grade number. The higher the ABEC grade, the better the bearings tolerance. For skating you will find that there are ABEC1, ABEC3, ABEC5, ABEC7 & ABEC 9.

What do these numbers mean? Well if you imagine the perfect ball bearing (the ABEC10). This means perfectly round balls, perfectly built shape and so on... ABEC9 is regarding as very close to that standard, ABEC7 is still excellent, close to the theoretical perfection, and it becomes less and less as you move down to ABEC1.