Kit & Gear

REVIEW: Merrell MTL Skyfire 2

Introducing Merrell’s lightest and fastest trail running shoe. Made for trail and sky runners to excel on the most technical mountains and rugged trails in the world. 

A grippy, lightweight design and secure fit gives athletes more confidence on technical terrain and an advantage on shorter, steep trails. 

The MTL Skyfire 2 is built for elite-level performance.

Our SportsShoes Trail athlete, Ben Mounsey, has been busy putting these exciting new trail shoes to the test. Check out his review below;

Most suitable for:Trail racing on technical, mountainous terrain.
Stack height:25mm (Heel) / 19mm (Forefoot)
Lug depth:5mm
Fit (width):Thin, precision fit
Fit (length):True to size
Key features:Super-lightweight and breathable mesh upper, Dual Density FloatPro Foam Midsole which reduces impact and stress placed on joints, a rockplate for protection and Vibram MegaGrip High Performance Rubber Outsole which provides excellent grip on both dry and wet surfaces.
RATINGS:(out of 5)

The Merrell MTL Skyfire 2 in summary;

Super-lightweight and very breathable

Comfortable to wear and a great fit (precision)

Built for Speed. Ideal for Skyrunning, mountain and trail racing on a range on trail surfaces

Grippy Vibram outsole with 5mm lugs

Perfect midsole balance of close ground feel and cushioning/protection

It has a flexible rockplate (Flexplate) in the midsole for protection and stability.


Last year, I headed to the Basque Country with Merrell for the Gorbeia Suzien Skyrace, the finale of the Skyrunning World Series 2022, where I took part in the 21km race and tested the Merrell MTL Skyfire 2. It was the perfect opportunity to really put this exciting new trail running shoe through its paces and you can read all about my experience here.

This weekend, we are returning to the race with Merrell and our 4 x Strava Segment competition winners, who are preparing to tackle the 21km and 32km Skyraces. They will all be competing in the new MTL Skyfire 2.

Find out more about the competition here.


First impressions

I instantly knew that I would love this shoe because it ticks all the right boxes.

Firstly, I really love the colour and eye-catching design.

Secondly, it feels amazing to wear. It's comfortable, super-lightweight and has a breathable mesh upper that promotes air-flow and offers just enough protection from the trail.

Thirdly, in terms of fit and feel, it really suits the shape of my feet. I would describe this shoe as precision fit in width and true to size in length. So, when I'm bounding around on the trails and leaping from rock to rock, I barely even notice that I'm wearing shoes as the feeling is very natural and I feel completely connected to the ground.


The upper

For me, the main advantage of the upper is the fact that the materials are so lightweight and breathable. Your feet won't stay dry on wet trails, but water will instantly drain and release, so the weight of the shoe will never be compromised during a run or race. Despite being a 'stripped back' design, there is a cushioned pillow built around the collar which ensures comfort and protection. In terms of support, there isn't much built into the upper structure aside from excellent heel support, which is mostly provided by the Flexplate (rock plate) in the midsole, extending into the upper at the back of the shoe and cupping the heel (see image of the heel further down).

The tongue is extremely lightweight, designed to save weight and to also help with drainage. In all honestly, I would prefer a slightly longer design and something slightly more padded to soak up the pressure of the laces. Ideally, I would also prefer a gusseted tongue design (which is more connected to the upper at both sides) to repel mud and debris. Lastly, a white elasticated strap spans across the lacing structure which allows you to store the laces safely once tied. I always double-knot my laces, so tend not to use this feature as the excess lace isn't long enough to store in here once I've tied them. Something I really like is the lace material. Slightly textured and very strong, they always tie well and stay together during a run - a very important feature of a traditional lacing system!


The midsole

This shoe features a relatively low stack height compared to more cushioned trail shoes on the market and the advantage of this lower-profile shoe is that it's designed to keep you more closely connected to the trail. Built for speed, with exceptional ground control, it allows your feet to move more naturally when navigating challenging off-road terrain. No 'wider than your foot' platform that's going to catch the edge of a rock and cause you to trip up and fall over. But a precision fit design that's perfectly suited to racing - exactly what I look for in this kind of model.

The Flexplate which runs through the midsole helps to keep your feet protected from sharp rocks and provides plenty of stability and support when negotiating technical terrain. Despite being a low-profile shoe, it still has plenty of cushioning in the midsole and I think Merrell has found the perfect balance and blend of cushioning and close ground control. For example, trail and mountain races often start on the road in villages and towns, before hitting the trails and climbing to lofty peaks. Therefore, trail shoes need to be able to comfortably handle a mix of terrain and surfaces, something which this model is more than capable of doing. That said, I obviously wouldn't wear them for a pure road race - but they can more than handle sections of road as part of a training run or race on the trails.


The outsole

The Vibram rubber is grippy and reasonably aggressive with 5mm arrow-shaped lugs. The lugs are also well-spaced and the pattern allows mud to escape easily without clogging underneath. I would confidently say that this is a 3-season outsole, capable of handling a wide-range of trails and terrain, the only exception being extremely muddy conditions, when anything less than a 7-8mm lug just won't live up to the task.

As mentioned above, I wore this shoe straight out of the box for the Gorbeia Suzien 21K Skyrace in the mountains of the Basque country, where the underfoot conditions in October are parallel to UK fells. Needless to say, it was a baptism of fire for the MTL Skyfire 2 and by the end of the race I was very happy with their performance. My only criticism relating back to lug depth, when for a few short sections of that particular course, I needed a shoe with just a little extra bite.



The biggest compliment I can pay the MTL Skyfire 2 is to say that I would choose to race in it. I am VERY choosy about what I wear for racing and having tested every comparable trail shoe on the market, this speaks volumes.

Mostly, I love the super-lightweight design, plus the shape and profile perfectly suited to my feet and preference. It drains well and it's exceptionally breathable, so when I'm crossing through streams and running over boggy moorland they drain well and don't soak up water and feel heavy.

The MTL Skyfire 2 is not a daily training shoe, it's a very specific and niche model and I would absolutely recommend it if you're looking for an elite-performance trail racing shoe. It's shoe that is built for speed, when every seconds counts and you want that extra edge over your competitors.

Interested in the latest shoes, apparel and technology? Then head over to our Kit & Gear category for more reviews, tips, advice and product releases.


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