The Spitfire Formula Four has been available for a quick minute now, and we've all heard what “game-changing” technology is apparently crammed into these rounded blocks of urethane. They skate faster, they're easier to control, they're more durable, and they last longer than Bones STF — their direct competitor. At least that's what Spitfire claims, and it's what Spitfire fanboys have been shouting from the hills since these things hit the market sometime in late 2013. But are the Formula Fours really a smash hit? Do they actually blow the tried-and-true Bones STF out of the park? I figured it was time I investigated the wheels myself, and the answers aren't as clear-cut as I first imagined.

First of all, I'll be upfront — I've been a Bones man for years. The STFs have been my go-to wheel choice without much thought of switching, and even when the Formula Four hit the market with all the buzz and hype of a blockbuster film, I stuck to what I knew was good. In saying that, I'll always look at another product with an open mind, and I was super excited to finally give the Spitfires a whirl.

The exact products I'm reviewing here are the Spitfire Andrew Reynolds F4 99-Durometer Wheels in 52mm, and the Spitfire Classic F4 101-Durometer Wheels in 52mm. The 52mm size is by far the most common for this wheel, and it offers a good balance between small and large, in order to be as impartial as possible. Both wheels are the classic shape.

101 Duro vs 99 Duro — What's the Difference?

To somebody unfamiliar with wheel jargon, 101d and 99d are probably completely foreign terms. Even if you've been skating for a while, it's entirely possible that you've never come into contact or had to worry about this number, but it's a pretty important identifier. Basically, the durometer of a wheel determines how hard it is. The lower the number, the softer the wheel. That's the basic gist of it, anyway. If you've ever skated both hard and soft wheels then you'll know how that hardness effects the wheel in other ways, in terms of grip, speed, and so on. If you haven't, then you needn't worry, because I'm going to be comparing the two-wheel durometers as well as putting them up against their Bones STF counterparts in this review.

101 Duro

The first thing you'll notice when you skate the 101 duro wheels is that they aren't afraid to slide around. As someone who had been riding softer wheels before chucking these on, it definitely took some getting used to. After riding them for a little while, it quickly became apparent that despite being slippery, these wheels are extremely intuitive to control, akin to Bones STF controllability. Once you figure them out, they become an absolute blast to ride. Powerslides are super easy to hold and control with the 101s, and reverting 180s in the parks and streets alike is a breeze.

A front-on view of the 101 duro F4