- diameter (size) - given in millimeters (mm)
- hardness - given as the value of "A"
While the size of wheels depends in most cases on the frame, the hardness of the wheels is selected individually and has a significant impact on comfort and safety.
In most cases the hardness is printed on the surface of the wheel or given as a specification on the packaging or in the product description.
The higher the "A" value, the harder wheels are, and thus, without going into the details of construction you can take the following principles:
- the harder the wheels, the greater is their durability. Harder compound PU is resistant to abrasion and wears much more slowly when braking or making slides.
- the harder the wheels, the less the grip. Hard wheels, touch the surface less which significantly decreases their grip.
- harder wheels are faster. Less grip resulting from greater hardness , reduces the abrasion.
- harder wheels dump vibrations much worse. Skating on uneven and rough surfaces on wheels with a lower hardness is much more comfortable
These principles can be seen as universal for all kinds of wheels, but keep in mind that the characteristics and properties of the wheel does not only depend on the "A" ranking, but also:
- the shape, structure and size of core (hub)
- Polyurethane mixture from which they are made
- additional technological solutions used in the construction
- shape and wheel profile
Therefore, two wheels from the same company with the same hardness, but with a different core structure and profile and made of a different material will behave differently.
How to choose the hardness of the wheels?
- Under 80 A - designed for sports halls or in areas with a very good and perfectly smooth surface, requiring wheels for increased grip.
- 80 – 84 A – standard hardness range of wheels for Fitness / recreation. Wheels characterized by average speed, good grip, and above all for their ease of use on different types of surfaces.
- 83/84 –87/88A– used primarily in the disciplines that require fast and wear resistant wheels: slalom, freeride, urban skating, speed skating, powerblading.
- Above 87/88 A– wheel are used primarily in aggressive skating and freeride. Skaters who use this type of wheels are very aware of the low-grip (which is used when making slides) and require usage of wheels with maximum durability to facilitate jumps, grinds and skating on not-perfect surface.
Some manufacturers use their own wheels hardness scale. In the case of Matter the scale is "F" (footprint). The higher the value "F" the softer the wheels.
Matter introduced the "F" scale, since it was very hard to determine hardness of wheels created for different surfaces only by the “A” rating.
When selecting a hardness of wheels we should also be aware that our skating techniques, braking, surface and even our weight can affect the skating characteristics.
When buying new wheels we should also check the hardness of the previous model and evaluate whether we need wheels with greater grip or a bit more durable and faster.