Most inline skate and roller skate wheel bearings are standard 608 sizes, with an 8mm bore, a 22mm diameter, and 7mm width (open, sealed, non-serviceable, shielded).

They can be used for inline, scooters, skateboards, and quad speed skating.

You can also find other sizes here:

  • 627 sizes, with 7mm bore and a 22mm diameter and 7mm width (open, sealed, or shielded), used for artistic and recreational quad skates and some quad speed skates.
  • 688 sizes with an 8mm bore and a 16mm diameter. It is 4mm wide (unsealed) or 5mm wide (2 shields). This micro bearing is used in conjunction with some speed skate wheels.
  • 698 sizes, with an 8mm bore and a 19mm diameter, and 6mm width (open, sealed, or shielded). This micro bearing is compatible with some speed skate wheels.

While many inline and skate bearings are rated according to the ABEC scales.

Some companies have their own rating systems.

Usually, seven ceramic or steel balls are used in each bearing.

However, some systems may use more.

These are the bearings you might find when upgrading or shopping for equipment.

How do you know if a bearing’s quality is good?

Bearings all look the same, so simply looking at them is impossible to tell which one you have.

So It is best to purchase from a trusted brand.

ABEC and Other Rated Bearings

Annular Bearing Engineering Committee(ABEC) is the name of the committee that rates bearings around the globe.

The scale is composed of nine levels, each with an odd number.

This number indicates how precise the bearing and tight the tolerance will be.

A bearing of standard 608 sizes with a higher ABEC rating is not necessarily faster.

It simply indicates that it is more efficient.

  • ABEC 1 bearings can be less expensive and more precise than other bearings but are likely to last longer.
  • ABEC3 bearings can be found in budget skates for children and beginners, but they are not recommended for speed.
  • ABEC5 bearings are available in many fitness and recreational inline skates.
  • ABEC7 bearings are very smooth and fast, but they can also be expensive.
  • ABEC9 and higher bearings are not required for most inline-skating activities.

These four questions determine the ABEC rating for a bearing

  1. How close is the bore to 8mm in microns(a micron is one-millionth of a meter)?
  2. What is the distance between the outer diameter to 22 microns?
  3. How close is the width to 7mm in microns?
  4. What is the rotation accuracy in microns?

ABEC isn’t the only rating system for inline and roller skate bearings

There is also the International Standards Organization system (ISO) and the German National Standards Organization system (DIN).

Below is a list that will help you compare these three systems.

  • ABEC 1 = ISO 0 (“normal”) = DIN 0
  • ABEC 3 = ISO Class 6 = DIN P6
  • ABEC 5 = ISO Class 5 = DIN P5
  • ABEC 7 = ISO Class 4 = DIN P4
  • ABEC 9 = ISO Class 2 = Din P2

Precision Bearings

Standard 608-sized precision bearings are available on the market, but they do not conform to the ABEC rating.

These bearings are known as titanium, Swiss, or ceramic bearings.

It is difficult to compare them since they do not belong to a formal rating system.

These bearings are generally good performers, with ceramic bearings being the best.

Manufacturer’s Bearings

Many companies making skating equipment are now naming the ratings of the bearings they make in different ways.

  • Rollerblade uses “SG”, rated bearings.
  • Bones Bearings are Skate Rated(TM).
  • K2 uses “ILQ-rated bearings.

Micro Skate Bearings

Micro bearings may be ABEC, precision, or manufacturer-rated.

They are also available in a 688 dimension – which is half smaller and half the weight of standard 608 skate bearings.

Although these bearings are not often rated, they are well-known for their performance.

Micro bearings contain more ball bearings per bearing housing to distribute the weight of a skater more evenly.

This allows them to operate more efficiently.

These bearing types can also be found in various sizes to fit different skaters needs.

Is it better to have more or fewer balls in a bearing?

Company A will argue that less friction means faster bearings, while company B will say that more balls mean less weight on each ball, which results in a faster bearing.

Which one is correct? Both are the same.

The friction is reduced if you have fewer balls.

However, each ball carries more load. Increase the number of balls to increase friction, but each ball carries less load.

Testing revealed the same results.

What is the fastest skating bearing?

Like the question above, fastest skate bearings are made from the best materials and have the highest tolerances.


My name is Patricia Toh. I was born in the southen of China but I live in Hawaii. I work as a translator. I love skating. But in the future, I’d like to try yoga too."

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