Skates typically use two different kinds of bearings, depending on your skates. These two types of bearings are 627 and 608 bearings.
What’s the difference? The hole in the middle that the axle goes through. A 627 bearing has a 7mm hole, while a 608 bearing has an 8mm hole.
Do you need to know which kind you have? Absolutely. Most likely your skates use a 608 bearing. However, if your skates are made for a 627 bearing (7mm axle), you need to use spacers in order for 608 bearings to fit properly.
Most all bearings are rated in a system called “ABEC scale”. In the skating world, this is often referred to as “ABEC rating”. ABEC has nothing to do with skating at all. In fact the bearings we use for skating are often not designed for skating at all. The 608 and 627 bearings were originally designed for use in industrial applications and are very common in sewing machines. The ABEC scale is one that is meant for understanding the precision to which the bearings were manufactured. The ABEC scale is odd numbers, from 1 to 9, though if you look at longboards, you will see ABEC 11 bearings. An ABEC 1 bearing will have parts that aren’t held to the same standard as an ABEC 5 or ABEC 9 bearing. That standard is how far off from specified measurements each part is allowed to be.
It is important to note that 608/627 bearings are very often designed for high-speed applications where there will be very little load on the bearings. Skaters exert a load on bearings that are much more than what is normally intended for these types of bearings. That is one of the shortcomings of the ABEC scale. While it exemplifies the tolerances used in manufacturing, it does not take into consideration the materials used. Sometimes the materials used in an ABEC 9 bearing are softer or more susceptible to rusting than those used in an ABEC 1 bearing. That will often mean that some ABEC 9 bearings may deteriorate quickly and cause poor performance.
That is not to say that ABEC rated bearings are not suited for skating. I also would not claim that the ABEC rated bearings suited for skating are bad; some are certainly great. What I am suggesting is to not fall into the misconception that many skaters fall into. Don’t think that because you see ABEC 9, the bearings are good. It is possible for an ABEC 3 to outperform and outlast an ABEC 9.
There is an alternative to ABEC ratings. There are many bearings that are sold for the purpose of skating that don’t advertise an ABEC rating. These are often referred to as “skate-rated”. These are normally made popular through word of mouth and brand recognition. There is really no standard of comparing these bearings other than trying them out and seeing for yourself.
So how do you pick out bearings for your skates? Ask around, look for reviews online, maybe even buy a few sets and try them out.
If you try several sets out, be aware that there is a break-in period. This period will be different depending on the bearings, but is normally not much more than a couple hours of skate time.
I have a few suggestions for selecting bearings based on my personal experience and that of others around me:
Stay away from BSB and KWIK bearings – These brands make bearings that often never spin freely, or they break down quickly.
For a good mid-range bearing, I like Bones Reds. These are excellent bearings for the price ($30-40).
For a much higher end bearing, I can’t recommend ILQ-9 bearings by Twincam highly enough. After switching to my ILQ-9 classics, I believe I will be skating on ILQ-9 bearings for the rest of my life. The classics are available for $36, the pros are available for $45.50 and the BCBs (ceramics) are available for $195. The BCB bearings actually come with a lifetime renewal program and a set of classics for when you’re having your BCBs cleaned.
All of the above mentioned bearings are 608 bearings. For 627 bearings, you’ll have to ask around for advice.