Roller Skates Anatomy - Bearings
This article is put together by Lou’s Skate Garage, a trusted skate building and maintenance service in Melbourne, Australia. Questions and comments to be directed to louskategarage@gmail.com
Table of contents:
Bearings
Terminology
ID = Inside Diameter/bore
OD = Outside Diameter
W = Width
ABEC Rating = The level of PRECISION (not speed) a bearing is kept to when manufactured. More precision does not necessarily mean it will be faster. Higher the number, the more precisely manufactured a bearing is.
Raceway finish = how polished the races the ball bearings roll along.
Radial load = force applied downward on the inner race. IE, standing in your skates.
Axial load = force applied into the side of the inner race. IE, when you push /stride on your quads, or make a turn.(inlines mostly create radial loads because the wheels get to lean)
Starting torque / running torque = The energy required to initiate rotation.// The energy required to run a bearing at a specific speed.
Cages/retainers = The part which keeps the balls separate from one another. They can be made from steel, brass or plastics/polymers. If a cage fails, the bearing will come apart. This is usually the cause of bearing failures, not that the raceway or balls wore out.
Bearings are made up of 3 (non precision) to 4 (precision) basic components. Outer raceway, inner raceway, ball bearings, and if a "precision" bearing , it will have a retainer to separate the balls and keep them in proper spacing. A "full compliment" version does not use a retainer. It simply fills the entire raceway area with balls, these are essentially the worst for what we want in skating. They require an incredible amount of running torque compared to precision bearings with retainers/cages...
Types of bearings commonly in use in skates.
"Normal"
608's 8mm ID x 22mm OD x 7mm W - most common axles OD
627's 7mm ID x 22mm OD x 7mm W - mostly Roll-line axles
So the only difference is that the ID is different. They handle loads the same, so they perform the same. The only difference here is the size of the axles they will properly fit on. Typically these bearings come with a 7 ball compliment. Though there are 8 and 6 ball versions.(FAFNIR and Qube 8 ball, and Bones Super Swiss 6). There are absolutely NO tests I can find that any ball compliment is better than the other.
"Micros"
688's 8mm ID x 16mm OD x 5mm W
167's 7mm ID x 16mm OD x 5mm W
Same as above with the normal bearings. However, the 167 is a "Bont" specific bearing. No one else makes a 688 sized bearing with a 7mm bore.
These bearings typically come with a 9 ball compliment, but there are also 7 ball and 11 ball versions. The 7 ball compliment micro is NO GOOD. It should come as no surprise that the smaller bearings are lighter, but they are also weaker. They can handle about 1/3rd of what a normal bearing can. If you're heavier than 80kg and do a lot of very hard cornering and hockey stops, you may want to shy away from them unless you're ok with replacing them more often than ‘normal’ bearings.
“Loose balls” / “cup and cone” bearings
Mostly present on vintage wheels, a loose ball bearing system is composed of loose ball bearings, a cup that the bearings sit in (usually integrated to the wheel hub) and a cone, which applies preload to the bearings. The contact surfaces of the cup and cone are machined to a smooth finish that matches the profile of the bearings, and this is what they run on.
Choosing the right bearings
There are many things that influence a bearing's performance, and just because you may have had "less performance/roll" with one brand vs another does not ALWAYS mean the one which rolled better is actually the better bearing.
BUT first off, YOU MUST KEEP YOUR BEARINGS LUBRICATED. PERIOD.
I cannot stress that enough. NO manufacturers sell bearings dry. Regardless of who you are or, what bearings you're using, the inside and outside diameters that the balls rotate on are NOT the same distance. This means that the balls must slip at some point. This is where 2 characteristics of a bearing come into play. 1, its looseness, 2 its lubricant. This is how the balls break contact with the outer or inner race and roll more efficiently. So how do you get the lowest rolling resistance? Well, this is where it gets a little more complicated.
Bearings are only part of the equation. There is also the environment you put them in. What I mean at this point is the wheels and the axles, not if you will use them in/outdoor. Many times a wheels hub is not perfectly made. This causes the bearings to sit slightly off from one another. The axles cause the wheels to not roll on the exact same parallel path if they are malformed or bent, which can make a skate feel slow, especially with grippy wheels as they will scrub speed instead of slipping if the bearing is built tightly and wont allow for a little play which takes up those imperfections. A bearing is tasked to deal with this problem. If you put a Qube8 ball which has a tighter internal clearance in equipment with less overall precision, a Bones Red will likely outperform the Qube, even though Qube8 balls are a better bearing. So you can see where an unknowing skater who had a bad result could incorrectly decide " those bearings suck". This means you need to consider the level of precision your skate is. Bones Reds are the best to just reliably buy and use.
Cleaning your bearings
Keep your bearings clean. Regularly wipe of dirt and grime around the wheels and bearings. Put a drop of bearing lubricant. Also keep both rubber seals or metal shields on to minimize contaminants getting in and keep them lubed at appropriate intervals, based on the lubricant you use. Getting an array of high quality wheels will net you better performance than spending that money on "ceramics" where you might get 0.1% better roll
BIG FAT DISCLAIMER
Take everything with a grain of salt - don’t trust anyone blindly and do your research, experiment and see what works best for you and your use of your skates.
There is no universal/miracle solution.
And remember…..
Keep roller skating fun :)
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Sources :
olisskateshop.co.uk
rollerskatenation.com
gingerskates.nl
derbywarehouse.com
doublethreatskates.co.uk
rollergirlgang.co.uk
roller.sk8.berlin
derbygearadvice.tumblr.com
QuadSquad FB group
The vintage skates coalition FB group
Extreme quad skate builds FB group
Corey skates PTY LTD FB group
rollerskaterevival.com
rollerskatedad.com
rollerskatedad.com
rollergirl.ca
machinedesign.com
bikeradar.com
