Mini Roller Skate Bearings 688 and 167

If you skate quads or inlines or a skateboard, you will eventually have questions about mini (micro) bearings specifically 688 bearings. What do they do? Where do they go? Which ones should I get? I'm going to cover all of your questions here. 

The Basics

As we are talking bearings for skating, this blog post will only be covering ball bearings. Bearings provide the rotational requirement that your wheels need to move. They allow your wheels to spin. They are a pretty simple machine and only have a few components. An inner race, which connects the bearing to the axle, an outer race, which connects the bearing to the wheel, the actual ball bearings, which provide the spin, and the cage that keeps the ball bearings where they’re supposed to be. Optional on these bearings are shields, which protect these components from outside contamination.

Bont 688 mini micro bearingBont 688 Mini Micro Bearing

Bearing sizes

Skate bearings can generally be divided into two groups: Standard and Micro (Mini). Standard bearings will be either designated 608 or 627. 608 bearings have an 8mm inside diameter, a 22mm outside diameter, and they are 7mm in width. They are by far the most popular size and are used in quad skate wheels, inline wheels, and skateboards as pretty much everything has 8mm axles. 627 bearings are identical to 608 with the exception of a 7mm inside diameter. 

READ MORE: The Truth About Skate bearings by Alexander Bont. Find out about how Bont tests bearings, which bearing oil is best, how can you tell if a bearing is good or not and many other 608 bearing questions. 

Why are there so many bearing sizes?

An axle is the part of the roller skate that the wheels slide onto. Axles come in two thicknesses which are 7mm and 8mm. 7mm axles are lighter but they need to be made of more expensive materials to make sure they are strong enough so 8mm has become more of a standard size for today's roller skates.

  • 608 bearings are your standard bearing that fits an 8mm axle
  • 627 bearings are your standard bearing that fits a 7mm axle
  • 688 bearings are smaller in size but also fit an 8mm axle
  • 167 bearings are designed and manufactured only by Bont which are a mini bearing for a 7mm axle

Why would I want a micro or mini bearing?

Mini 688 and 167 bearings weigh just 4 grams (0.14oz) per bearing. A mini bearing adapter weighs 1 gram. 608 or 627 bearings weigh 12 grams (0.42oz) per bearing. It doesn't sound like much but you use 8 bearings per skate you can save 40 grams (1.4oz) which is a noticeable amount of weight on your feet. 

Secondly, mini bearings spool up faster so if you are doing fast sprints, or constant stopping and starting, mini bearings are better than full-size bearings. The downside is that they are not as strong so I wouldn't recommend them for jumping. 

Why did Bont make the 167 Bearing?

Bont is always looking to make lighter skates so when they created wheels that were made for mini bearings such as the Royal Assassin and FX1, there was no 7mm micro bearing on the market so they created a new bearing size. 

Bont 167 mini micro bearingBont 167 micro mini skate bearing

Which Bearings are Best?

This is a thing that will be debated until the end of time. The 608 bearings that fit in the wheels we use for roller sports are a very common bearing in the industry. They are mostly used in electrical motors that will spin at a few thousand rpm for thousands of hours without requiring service. Why am I bringing this up? The stresses we put these bearings through are small compared to what they are typically designed to do. Do you need the most expensive bearings available? Probably not, but it’s a good idea to purchase bearings manufactured by a company with a history in precision manufacturing. Bont 167 micro bearings are made by Jesa, a Swiss manufacturer that’s been producing bearings for over 40 years. 

Bont 688 Micro BearingBont 688 Micro Bearing

ABEC Rating

What about the ABEC rating? The ABEC rating is based on tolerances in manufacturing. The higher the rating, the smaller the allowable tolerances. Any ABEC rated bearings are made to a minimum of ABEC 3 rating, as that is the tolerance set in the machines that produce them. ABEC 9 bearings are made top the smallest of allowable tolerances and are used in super expensive industrial equipment. Will these make a difference in how your skates perform? Perhaps, but you probably are going to gain more performance from more squats or stride training. Bont make a range of bearings to fit any budget starting at just $25 a set.

Should I clean my bearings or get new ones?

This is a question I get quite a bit. The answer is simple. Clean them, unless you don’t want to bother. In that case, get new ones. Cleaning or replacement is required due to a lack of roll, or “crunchy” roll that you might notice after skating for a few weeks or months, depending on how often you skate, or where you skate. Bearings in skate wheels see loading axially (down, when you’re rolling in a straight line) and radially (thrust, or sideways load, when you’re crossing over or turning) but if you do any sort of jumping, your bearings will see those loads combined and with impact added. The grease or oil helps disperse these loads, but the bearings will still wear as they are metal bits contacting other metal bits. Those metal bits are what you’re feeling when your bearings get “crunchy”. If you skate in extremely dirty conditions, it’s possible for some dirt and other particulate matter to get into your bearings as well. 

There are quite a few acceptable ways to clean mini 688 and 167 skate bearings, depending on what materials you have at hand. Here is how I do it:



Flustercluck skates for the Vancouver Murder and Team Canada and has been skating since 2011. He is the head coach for the Calgary Roller Derby WFTDA travel team and SAJRD Level 3 Juniors. Fluster has a keen interest in all things mechanical and will go into detail regarding any part of your skates if you let him.