Merrell MTL Skyfire 2 Review: Speed Demons for Steep Technical Trails

The Merrell MTL Skyfire 2 trail running shoes are designed for runners who crave speed and agility on the trails, that much is clear, but how do they truly perform across a variety of terrains, including climbs and descents? Are they suitable for ultra running, and ultimately, are these skyrunning trail shoes worth the $200 price tag?

Well, I’ve put these shoes through their paces on some of the most epic trails in Northern California, so that I can share my insights with you all in this Merrell MTL Skyfire 2 review.

The MTL Skyfire 2 looks as badass as they come; they’re super minimalistic, focusing on speed and agility in mountainous terrains. With a low stack height and an incredibly lightweight build, these shoes are all about performance and control.

Before I get into my performance review, here’s a breakdown of the key specifications / features worth knowing about.

Key features of the Merrell MTL Skyfire 2

• Price: 🇺🇸 USA ($140) / 🇬🇧 UK (£170) at Merrell.com
• Weight: 7oz (198g) for a Men’s size 9 (my pair)
• Drop: 6mm (Stack height: 25mm heel, 19mm toe)
• Outsole: Vibram Megagrip with 5 mm lugs
• Upper: Breathable TPU engineered mesh (not as durable as the MATRYX Upper Version)
• Midsole: Dual-density FloatPro foam with a flex plate
• Fit: True to size with a medium width

The upper features a breathable TPU engineered mesh, perfect for keeping your feet cool during those hot California runs.

It’s not going to be as durable as the Matryx version of this shoe – due to the very nature of the MATRYX material which is best in class for uppers right now but that version does cost a little more money.

There’s an elasticated loop for stowing your laces, which keeps them tucked away neatly, especially handy during races. The tongue is minimalistic but functional, with a small loop for the laces to pass through, to keep it in place.

One extra special feature is the dual-density FloatPro foam midsole which is essentially two layers of foam with a lightweight flex plate sandwiched between them, offering torsional rigidity and excellent energy return for fast, stable running.

The Vibram Megagrip outsole with 5 mm lugs provides exceptional grip on all terrains which I’ll go into more depth on in just a moment.

Merrell Skyfire 2 performance review

When it comes to fast and light, mountain trail running shoes, performance is everything. The Merrell MTL Skyfire 2 is no exception.

To make sure this review offers you the full scope of testing insights, and so you know we actually run in the shoes we review (believe it or not, some sites that like to cut shoes in half and call it a review, do not), you can also watch my performance video review on Youtube by tapping the image below – Don’t forget to subscribe to our Channel :).

Okay then, let’s get straight into how the MTL Skyfire 2 performs in different scenarios on the trails, including comfort and fit, climbs, flat sections, and downhills.

Comfort and Fit

The Merrell MTL Skyfire 2 is designed to be minimalistic, but that doesn’t mean it sacrifices comfort in the way that you may think. Yes, they’re firm under foot but the design of the upper allows for a really nice snug fit. They fit true to size and have a medium width, accommodating the majority of foot shapes.

I also like how the toe box offers enough room for your toes to splay out naturally, which is crucial for maintaining comfort, and proper running biomechanics during long runs and steep climbs.

The upper is made of a breathable TPU engineered mesh that keeps your feet cool even in hot conditions. Running in the California heat, I find the breathability to be excellent, they regulate temperature well, preventing that uncomfortable overheating that can ruin a run.

Despite the minimal padding under foot due to the low stack height, the shoes manage to provide a snug and secure fit. The tongue is ultra-minimal, with a little loop for the laces to thread through which helps to keep it in place. There’s also an elasticated loop for stowing your laces, which is a thoughtful touch for those who dislike their laces flapping around.

They also have a good heel lock when done up tightly, with internal padded areas around the heel counter area to help provide a cushioned fit, and extra heel lock – see photo below.

However, it’s important to note that these shoes are not designed for those who need a lot of cushioning. The dual-density FloatPro foam midsole is responsive but firm, so if you’re someone who prefers a softer, more cushioned ride, you might find the Skyfire 2 a bit too harsh for longer runs – I’ll share some alternatives that may suit you better at the end of this review.

Holy hill, the Skyfire 2 climbs damn well!

Climbing is where the Merrell MTL Skyfire 2 truly shines; they are incredibly lightweight (7oz per shoe), making each step feel almost effortless. The breathable upper ensures your feet stay cool, which is particularly important during intense uphill efforts.

The Vibram Megagrip outsole with 5 mm lugs provides exceptional traction on all types of terrain, whether you’re dealing with loose dirt, rocky surfaces, or muddy trails, these shoes grip the ground like a dream.

There’s no slippage thanks to the aggressive 5mm lugs that claw into the trails, allowing you to maintain a steady and efficient climb.

The flex plate in the midsole adds another layer of performance enhancement.

It has excellent energy return, giving you a little boost with each step, and unlike stiffer carbon fiber plates, the flex plate in the Skyfire 2 strikes a perfect balance between rigidity and flexibility. It supports your foot without making you feel like you’re fighting against it on the climbs.

Another feature that aids in climbing is the spacious toe box which allows your toes to spread out and push off more effectively, which is critical when tackling steep inclines. The dual-density FloatPro midsole, while not plush, is responsive and helps conserve energy during climbs too.

They’re extremely fast on flat sections

When transitioning to flat sections, the Skyfire 2 adapts really well, I attribute this to the low stack height and lightweight design that encourages a fast cadence and extended stride. You can see me really open up my stride in my video review on Youtube.

You can really open up your legs and get into a rhythm, making these shoes perfect for picking up speed on flat terrain.

The flex plate and dual-density midsole work together to provide a responsive and stable ride, and it’s the torsional rigidity from the plate ensures that your foot stays aligned, reducing the risk of rolling an ankle due to instability. Those with pronation issues will appreciate this! The foam midsole offers just enough cushioning to keep you comfortable without sacrificing ground feel.

The Vibram Megagrip outsole maintains its superior grip even on flat surfaces whether you’re running on compact dirt, gravel, or rocky paths, the shoes deliver consistent traction and stability – this makes it easier to maintain your pace and focus on your run.

And they’re highly proficient when tackling steep, technical downhills

Downhill running can be particularly challenging, but the Merrell MTL Skyfire 2 handles it with ease. The aggressive Megagrip 5mm lugs dig into the trail, providing excellent traction, a critical feature for maintaining control and stability on steep descents.

The flex plate in the midsole offers additional support, reducing the impact on your feet and legs. It helps distribute the forces evenly, making downhill running feel smoother and less jarring, and it also acts as a rock plate of sorts, protecting the bottom of your feet from sharp rocks on the trails.

The low stack height gives you a closer connection to the trail, allowing for quick and precise adjustments to your footing but without this plate, I think I would most likely be feeling the trail too much…

While the Skyfire 2 excels in responsiveness and ground feel, it may feel a bit harsh on very rocky or hard-packed surfaces over long distances. If your trails are predominantly soft or muddy, you’ll find these shoes to be extremely comfortable for even longer runs, however, on harder ground, you might feel the need for a bit more cushioning.

After all this testing on challenging trails, who are they best suited to?

If you’re an elite runner or someone who loves high-paced, technical trail races, the Merrell MTL Skyfire 2 is a fantastic choice for you. These shoes are perfect for vertical kilometers and shorter trail races up to 20 miles.

However, if you’re gearing up for an ultramarathon or prefer more cushioning, you might want to consider a trail running shoe like the Hoka Speedgoat 6 instead.

Alternatives trail running shoes to consider

• HOKA Speedgoat 6: More cushioning and a higher stack height, making it suitable for longer distances.
• Salomon S/LAB Pulsar 3: Similar responsiveness and excellent grip, though not as stable due to a narrower footprint.
• Merrell MTL Long Sky 2 Matryx: A bit heavier but offers more cushioning, making it a better choice for those who need a bit more underfoot protection.

Are the Merrell MTL Skyfire 2 worth buying?

So, is the Merrell MTL Skyfire 2 worth $200 (currently discounted to $140)? For the right runner, absolutely. If you’re after a high-performance, lightweight shoe for technical trails, these are a fantastic option. They offer excellent grip, stability, and a responsive ride that makes climbing and descending a joy.

However, if you prefer more cushioning or plan to run ultra distances, you might want to look elsewhere.

Thanks for reading! If you enjoyed this review, please give it a like, share it with a friend, and subscribe to our Newsletter for more running shoe reviews just like this one. See you next time!