Every race wheel LiveLica stocks arrives in two firmness options, XFirm and XXFirm, and the single most common question we get from inline speed skaters is a simple one. Which hardness should you actually skate? It sounds like a small detail, yet the compound you choose changes how the wheel grips the corner, how far it rolls on the straight, and how the skate feels underneath you for a whole session. Get it right and the wheel disappears under your foot, holding the line and carrying speed. Get it wrong and you either slide in the turns or feel like you are skating through treacle. This guide explains exactly what XFirm and XXFirm mean, how they behave, and how to pick between them for your surface, your weight and your event.
What durometer really measures
Wheel hardness is measured on the durometer A scale. The higher the number, the harder the urethane. On the wheels we stock, XFirm sits at 84 to 86A and XXFirm sits at 86 to 88A. That looks like a tiny gap on paper, only a couple of points, but urethane is sensitive stuff and those points are enough to shift the balance between grip and roll in a way you feel from the first few strides.
The key idea is that a softer wheel deforms more where it meets the ground. That larger contact patch is what creates grip. A harder wheel deforms less, sits up on a smaller patch, loses less energy to squish, and therefore rolls further for the same push. So the whole XFirm versus XXFirm decision comes down to a single trade off between grip and roll, and understanding that trade off is most of the battle.
Softer sits to the left with more grip, harder sits to the right with more roll. XFirm and XXFirm are close on the scale, yet the difference is easy to feel.
XFirm explained
XFirm at 84 to 86A is the grippier of the two compounds we stock. It is the wheel that holds when you commit to a corner and lean the skate over, because the softer urethane keys into the surface and gives you confidence to carry speed through the apex rather than scrubbing it off. On a hard, smooth and dry surface, a harder wheel can actually feel loose and start to break away, so counterintuitively the softer XFirm is the faster wheel there, since a wheel that grips lets you push harder and skate the racing line with trust.
XFirm is the sensible starting point for most skaters, most of the time. If you are still building your cornering technique, if your rink or track is polished and slick, or if you simply value a planted, secure feel, XFirm is the compound to reach for. The JUNK Voodoo XFirm and the MPC Black Magic XFirm are both excellent examples of a grippy race compound done properly.
XXFirm explained
XXFirm at 86 to 88A is the harder compound, built for the most roll and the highest top speed. Because it deforms less, it wastes less of your energy and keeps rolling for longer once you are up to pace, which is exactly what you want on a fast, grippy surface where traction is not the limiting factor. If the ground already gives you plenty of hold, a softer wheel simply squishes and gives away free speed, so the harder XXFirm lets you convert every stride into distance.
Choose XXFirm when the surface is genuinely fast and secure, when you are a stronger and heavier skater who can load a wheel and still keep it planted, or when your event rewards outright roll such as a flat, grippy marathon. The JUNK Voodoo XXFirm is the natural pick for skaters chasing straight line speed.
The softer wheel spreads a wider footprint on the ground for hold, while the harder wheel sits up on a smaller footprint and keeps rolling.
The surface decides more than anything
If you take one thing away, make it this. The condition of the surface matters more than almost any other factor. A wheel that is too hard for a slick, glassy floor will feel skittish and slide in the turns, robbing you of confidence and speed. The same wheel on a fast, high grip surface will feel planted and rapid. This is why the product notes for our race wheels repeat the same guidance. XFirm suits hard, smooth and dry surfaces where you want the wheel to hold, and XXFirm rewards you when the surface already gives you traction and you simply want to roll.
Indoor rinks, freshly laid road and warm dry sessions tend to favour a compound with hold, which nudges you toward XFirm. A very grippy, abrasive track where wheels bite hard can let you run XXFirm for extra roll. When in doubt on an unfamiliar surface, start softer with XFirm, because a wheel that grips is safer and faster than a wheel that slides.
Your weight and strength matter too
Body weight changes how a wheel behaves because a heavier skater loads the urethane more and squashes the contact patch further. A lighter skater may find XFirm still feels fast and secure, since they are not deforming the wheel as much to begin with. A heavier or more powerful skater can often step up to XXFirm and still keep plenty of grip, gaining roll without the wheel feeling loose. Think of your weight as a dial that shifts the whole grip and roll balance. The more you weigh and the harder you push, the more you can lean toward the firmer compound before you run short of traction.
When two or more rows point the same way, that is your compound. If you are split down the middle, start with XFirm.
Which LiveLica wheels give you the choice
Across the range, the compound choice is always there in the same two grades. The JUNK Voodoo is a pure, pigment free race wheel on a natural turbo hub, moulded one cavity at a time for consistency, and it comes in both XFirm and XXFirm. The JUNK Road Reaper is one of the most decorated wheels in the sport, available at 110mm in XFirm and XXFirm. The Killer JUNK carries a stiffer natural hub for extra momentum and is offered in the same two firmness levels. The MPC Black Magic, one of the most successful wheels ever made, uses MPC patented MTech build with a soft inner heart inside a harder outer body, and again you pick XFirm or XXFirm to suit your surface.
Because both grades share the same hub and construction within a model, you are only ever changing the compound, not the character of the wheel. That makes it easy to run the same trusted wheel and simply switch firmness as your surfaces and events change through the season. You can compare the full lineup in the wheels collection.
A note on hubs and build
Firmness is only part of the story, and it helps to know what sits underneath the compound. The JUNK Voodoo and Killer JUNK run a natural, pigment free hub and raw urethane, which JUNK say gives better roll, grip and durability because nothing dilutes the material. The Killer JUNK adds a stiffer hub for more drive out of corners. The MPC Black Magic takes a different route with its Soft Heart, Hard Body construction, wrapping a softer inner ring in a harder outer layer so the wheel can flex for grip while the outer body keeps rolling and lasting. None of this replaces the firmness decision, but it does mean a Black Magic XFirm and a Voodoo XFirm each have their own feel even at the same durometer.
Setting up your new wheels
Whichever compound you land on, remember that race wheels are sold as a set of eight with no bearings fitted, which is a full set for a pair of four wheel inline speed frames. You will need sixteen 608 bearings and the correct spacers to run them, all of which you can add from the speed bearings collection. Confirm the wheel diameter your frame is built for before ordering so the new wheels drop straight in, and rotate them regularly to even out wear and get the most life from the set.
Frequently asked questions
Is XFirm or XXFirm faster?
Neither is faster on its own. XFirm is faster where grip is the limit, because a wheel that holds lets you push and corner hard. XXFirm is faster where grip is plentiful, because it rolls further for the same effort. Match the compound to the surface and you get the fastest result.
What is the actual hardness difference?
XFirm is 84 to 86A and XXFirm is 86 to 88A on the durometer A scale. It is a small step in numbers but a clear step in feel.
I skate indoors on a slick floor. Which should I pick?
Start with XFirm. Softer urethane grips a slick surface far better, which keeps you planted through the turns and lets you carry speed instead of sliding.
Can I mix XFirm and XXFirm on the same frame?
Most skaters keep one compound per set for a predictable feel. Advanced skaters sometimes experiment with firmness by position, but if you are unsure, run a full matched set first and learn how it behaves.
Do heavier skaters need XXFirm?
Not always, but heavier and more powerful skaters can usually run XXFirm and still keep good grip, gaining roll in the process. Lighter skaters often stay happiest on XFirm.
Choosing between XFirm and XXFirm is really a conversation between your compound and your surface. Read the ground, be honest about your weight and your cornering, and pick the firmness that lets you push with confidence. If you would like a hand matching a wheel to your rink or your event, message the LiveLica team and we will point you to the right set.
