Closed grease bearing
You need 2 bearings per wheel.
These bearings are easy to press into the wheel and ensure smooth rotation of the wheels under heavy conditions.
Although uninformed staff in shops still even if you want to say the opposite, the abec basically says nothing about the quality of the bearings. According to manufacturer MBA, even ABEC 9 bearings are technically equivalent to ABEC 1 bearings within 10 minutes. Unless you skate on a 100% flat surface and you don't use your legs to propel you. As soon as you make a skating movement or take bumps, you create a shock load with a disastrous effect on your bearings!
The value(s) of ABEC
ABEC values are a standard for manufacturers to indicate the maximum tolerances (deviations) in the interior of the bearings. So the higher the ABEC number, the smaller the tolerances and the more accurate your bearings. A lower value than ABEC 1 is not made by quality manufacturers. The manufacturer stamps its name, the ABEC value and a code such as 608zz, the type designation, on the side of the bearing. Bearings with the name of a skate brand on it can be made by any bearing manufacturer (possibly by the cheapest one), but not by the skate brand itself.
What are these bearings intended for?
ABEC bearings are not primarily made for skates. They are high precision bearings for machines that need to perform precise work at a higher speed than another bearing could. A standard ABEC 1 bearing is rated with a maximum of 32,000 RPM, this speed partly depends on the weight used, but this is actually not relevant for skaters. High precision bearings do not go faster (!), they only enable high speed machines to operate faster without errors.
Higher ABEC values in skates
The main thing you will notice higher value bearings will find room in your wallet. Because after 5 to 10 minutes of use, the inner ring of the bearing is no longer completely centric and the balls will no longer be round. This means that your bearing has become equal in value to an ABEC 1! If you ride on a flat surface with new bearings and don't push off with your skates you might notice that you go faster. At least: as soon as you exceed 390 km per hour (32,000 RPM). ABEC values are therefore complete nonsense for skaters!
