On roller skate wheels and hardness
You picked a fine time to leave me, loose wheel…
Wheels are very important for roller skaters, seeing as how our entire hobby is based on having available, highly reliable rubber wheels to roll on.
Skate wheels are measured on the Shore durometer "A" scale. Shore durometer is a scale designed to measure the hardness of elastic polymers. Shore durometer readings are from 0 to 100. 100 represents the rod not penetrating into the material at all, 0 represents a penetration of 1/100 of an inch after 15 seconds. Making things more confusing, 101A and 103A skate wheels are more or less just a marketing term used by wheel manufacturers since those readings are actually impossible and just mean "a very hard skate wheel suitable for dance or ramp skating." And even more so, durometer readings between 90A and 100A are not actually meaningful at all in a chemistry sense; what those readings mean is “your reading is out of range, get a different durometer.”
Some skateboard wheel makers have begun doing that and selling wheels measured on the “B” and “D” durometer scales. This is not, however, universal practice and does not appear to be followed by any manufacturers of roller skate wheels; instead they continue to use the familiar A scale, even though for most indoor skating purposes the A scale is totally inappropriate.
One of the things that makes direct comparison of skate wheels difficult is that the Shore A durometer scale isn't very accurate in the range of hardnesses needed by skate wheels; Rubber hardness from 88A to 100A are inexact and two urethanes that are both rated at 93A might be very different.
Now with all of these words spilled, we’re still going to continue to use the A scale as skaters, because it’s the only scale in town until someone shows up to sell us all wheels that are measured on a more accurate durometer scale. So here’s Derby Warehouse’s wheel buying guide; hopefully it will help you make some sense of this madness.
So what can we take from this?
Higher numbers are harder - they will slip and slide more readily than lower numbers, which will grip more readily. Neither is necessarily better; you need to know how you skate for them to work for you.
In the area of hardness that we're dealing with, 88A to 100A, the science is inexact.
Considering this, the wheels that work best for you are going to take some trial and error, even if you're experienced.
