The most noticeable result is that you will end up with less money in your wallet and the people that sold you the bearings will be eating out at restaurants at your expense for a few days. Under the following conditions, you may notice an improved performance.

You spend a lot of money (i.e. thousands of dollars) to have your equipment (wheels and board) redesigned and manufactured to suit these high precision bearings. You will need to use some type of shock absorber that allows for absolutely no vibration. You will have to be prepared to skate on a perfectly smooth surface and make no attempts to use your feet to propel yourself. (Doing so would cause shock loads to the nsk bearings and any extra precision would be lost very quickly).After you work out how you are going to achieve the above two criteria, you may (and that is only "may") experience a better result than using ABEC 1 bearings after you attain a speed of about 390 KPH (240 MPH) with 65mm wheels and grease lubrication.

OK, but don't forget that you really do not need to waste money on anything higher than ABEC 1 or ABEC 3 for skating applications. It should also be pointed out that the precision grade only tells us how close the bearings dimensional tolerances are (that is, how close the bearing is to the stated size). There are many other factors relating to the quality of a bearing, and many of these factors will have much more of an impact on your skating experience than the ABEC Grade of the bearing.

There are a number of factors covered by the ABEC grades, but to give you an idea we will just examine one of these factors - the eccentricity (out of roundness) of the track in the inner ring. For an ABEC 1 (lowest grade) bearing, the maximum eccentricity allowable is 0.0075 mm (0.000295"). This is quite precise - more than precise enough for skates and skateboards. The figures for the other ABEC grades are 0.005 mm (0.000197") for ABEC 3, 0.0035 mm (0.000138") for ABEC 5, 0.0025 mm (0.000098") for ABEC 7, and 0.0012 mm (0.000047") for [ABEC 9 bearings] . If used in high precision, high speed machinery (see above), these minute variations can make a difference. The fact is that no matter which of these bearings you use in skates or skate boards, after 5 - 10 minutes of use the tracks won't just be eccentric, they will become irregular (albeit minutely) enough to be practically indistinguishable from one another. Your high priced ABEC 9 bearing might as well be a 50 cent ABEC 1 cheapie.

We have to believe that they are until it is proven otherwise. If the bearings are labelled as ABEC 7 then in most countries the manufacturers of the bearings are compelled by law to provide ABEC 7 bearings. Some of the low prices offered for high precision bearings in Supermarkets does look a little strange though. Manufacture of high precision bearings is not cheap, although the costs can be kept lower if other quality controls are not in place. Our Swiss quality supplier RMB has recently checked the tolerances of a set of bearings that was purchased at the Supermarket, and labelled as "ABEC 5". The bearings did indeed meet the standard of ABEC 5, but more costly tests would be needed to check all of the other important quality factors relating to the bearings (and many of these other factors are more relevant to skating). See point 11 also.

"Z" is a designation which means a steel shield covering the side of the bearing (for most brands). "ZZ" simply means that the bearing has a shield on both sides. Normally, the shield itself will be branded as "608 Z" even though there is a shield on both sides of the bearing. This is for practicality in manufacturing. It is much more economical to produce all of the shields stamped as "608 Z" than it would be to manufacture the exact same component with two different stampings on them. Some manufacturers supply bearings with removable shields, whilst others have shields that are crimped in place. Neither is usually better than the other unless you intend replacing the lubricant or cleaning the ntn bearing from time to time.