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Merrell MTL Long Sky - Women's Review

The best trail running shoe we've come across in years
Merrell MTL Long Sky - Women's
Credit: Merrell
Editors' Choice Award
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Price:  $130 List
Pros:  Excellent value, protective, lightweight, superior stability, cushioning for the long haul
Cons:  Short laces
Manufacturer:   Merrell
By Amber King ⋅ Senior Review Editor  ⋅  Jun 29, 2020
Our Editors independently research, test, and rate the best products. We only make money if you purchase a product through our links, and we never accept free products from manufacturers. Learn more
  • Foot protection - 20% 9.0
  • Sensitivity - 20% 7.0
  • Traction - 15% 8.0
  • Stability - 15% 9.0
  • Comfort and Fit - 15% 9.0
  • Weight - 15% 9.0

Our Verdict

The Merrell MTL Long Sky is a brand new shoe, designed in conjunction with Anna Frost, ultrarunning trail goddess, and pro athlete. They've designed what we feel is the best trail running shoe we've tested in years. It earns the highest accolades because it earns top points in all metrics we tested, inspiring confidence and comfort on the trail. We wore this shoe while tackling over 60 miles of trails in the steep alpine highlands of Ouray, Colorado. We gained scrambly gneiss ridges that climb 1,000 feet over a half-mile, crushed single track, and battled over rocky terrain. Whether you're trying trails for the first time or are a seasoned 100-mile ultra-miler, this shoe has something for everybody. Can you tell we have a bit of a crush?

The Merrell MTL Long Sky was discontinued in 2021.

Our Analysis and Test Results

The Merrell MTL Long Sky is our Editors' Choice award winner for its supportive and cushioned midsole, excellent traction, and superior stability. It's built for long (or short) days on the trail, with the ability to perform on any run, through any condition.

Performance Comparison

Merrell MTL Long Sky - Women's trail running shoes - this superb and versatile trail running shoe has quickly risen to...
This superb and versatile trail running shoe has quickly risen to the top, crushing it across the board. We appreciate its versatile fit and level of protection that's suitable for any distance and any type of runner.
Credit: Amber King

Foot Protection

We wore these shoes while running over rocky, snowy, and sandy terrain. We took them over the rock-laden trails found in Ouray, Colorado, hiking up steeps and sprinting down singletrack. We are overly impressed by the protective underfoot cushioning and rugged upper that keeps your foot protected all day long.

On any trail, underfoot protection is paramount, especially when you're running upwards of marathon distances. This shoe is stacked with 27.5 and 19.5mm of responsive cushioning in heel and forefoot respectively. Over sharp, rocky trails, very rarely did we feel these underfoot obstructions penetrate. We tested them on all sorts of distances, up to 25 miles. After those 25 miles, our feet were fresh and didn't feel sore, even after moving over sharp rocks and sand all day long.

Merrell MTL Long Sky - Women's trail running shoes - the mesh is quite breathable and offers a surprising level of...
The mesh is quite breathable and offers a surprising level of protection from smaller particulates.
Credit: Amber King

The upper is quite breathable. The mesh features porous holes that aid in breathability, making it dry out quickly after tromping through creek crossings. While it doesn't have any dedicated holes for drainage, the mesh functions as the drainage itself, which actually works better than any shoe we've tested with holes in the construction.

Merrell MTL Long Sky - Women's trail running shoes - even in muddy conditions, it'll keep your feet well protected. plus...
Even in muddy conditions, it'll keep your feet well protected. Plus, the outsole sheds mud efficiently.
Credit: Amber King

When running in sandy conditions, the secondary mesh layer offers good protection so pesky particulates don't enter the shoe. The only caveat is the toe bumper is quite flexible, making toe stubs more painful than other more protected options.


Sensitivity in this shoe is surprisingly above average, considering the amount of protection. In a lot of ways, Merrell has figured out the perfect balance between being able to feel the trail while protecting your foot.

While flying down rocky and root littered trails, we could feel underfoot undulations and correct our body position easily for uneven landing. This shoes' sensitivity is just so to get you intimate with the trail but protected enough to keep your feet comfortable for short or ultra distances. If you're a fan of barefoot shoes where you can feel absolutely everything, avoid this shoe as it's more cushioned and protected than most.

Merrell MTL Long Sky - Women's trail running shoes - even with its excellent protection, it is also quite sensitive.
Even with its excellent protection, it is also quite sensitive.
Credit: Amber King


Superior! The Vibram sole and 5-mm lugs offer excellent traction. We tested it while scrambling up granite ridges, over snowy surfaces, and while chugging away over kitty-litter laden rock. The lugs are durable enough for cross-over terrain on both dirt and pavement roads. Push off the ground is efficient and feels light. They also shed mud well.

This shoe was tested primarily in the dry climates of Ouray, CO, home to the Hardrock 100, and Ouray 100. The trails are steep, slippery, strewn with river crossings, snowfields, and rocks. They have literally seen it all. The chevron-shaped lugs are burly and durable. They offer superior traction when heading up steeps and while crushing the downhill.

Merrell MTL Long Sky - Women's trail running shoes - we love the vibram outsole and multidirectional lugs that grab the...
We love the Vibram outsole and multidirectional lugs that grab the trail on both the ascent and descent.
Credit: Amber King

Many shoes offer questionable lateral traction, but the pattern of the outsole, in addition to its stable design with built-in stability posts (even though they don't feel like stability shoes) adds excellent lateral traction when treading over slippery terrain. Basically, when faced with the decision to choose from over 15 other options for technical terrain, we typically opted for this one. It helped us choose to go faster on the downhills, without fear of slipping out and falling on our butts.

Merrell MTL Long Sky - Women's trail running shoes - we scramble up a ridge high above highway 550 in ouray, learning...
We scramble up a ridge high above highway 550 in Ouray, learning quickly that the rubber is sticky, even on these slabs.
Credit: Amber King


Again, wow! The Merrel Long Sky provides excellent stability on even the rockiest or uneven of terrain.

Our main tester is an ankle roller by nature, plagued with flashbacks of ankle rolling events, especially when traveling over rocky, unstable trails. However, this shoe gives her confidence. It might be the stiffer heel or the medial post that's inserted into the design. It might be the excellent traction or the flared skirt of material around the outsole, increasing posterior stability. Or, it might be the wider platform in the toe box, which equates to better balance. Whatever it might be, the result is clear. This is a stable shoe, but not rigid, that is built for stability. It's still flexible throughout its body and lightweight. Feel confident flying down the most technical or non-technical trails.

Merrell MTL Long Sky - Women's trail running shoes - jo appreciates the additional protection and stability of this shoe...
Jo appreciates the additional protection and stability of this shoe as she descends down this rocky trail.
Credit: Amber King

Comfort and Fit

We absolutely love the versatile fit and overall comfort of this trail runner. It features a wider toe box, a little arch support, and a tight-fitting heel cup. The fit, when running, feels specific. Comfort is heavenly. It has a traditional design with an 8-mm drop from heel to toe in its level of cushioning.

Fit is versatile. The toe box is surprisingly wide, even though it looks narrow at first glance. There is a tiny bit of arch support and a well-fitted heel cup. The heel cup is quite rigid but comfortable. The collar is thin with a broad profile across the Achilles and doesn't rub in any weird spots while running. The pull-on tabs make the shoe easier to get on and off, especially if you don't like tying laces.

Merrell MTL Long Sky - Women's trail running shoes - whether you're a forefoot or heel striker, this shoe will provide...
Whether you're a forefoot or heel striker, this shoe will provide the comforts you need for many miles on the trail.
Credit: Amber King

The tongue is attached to the upper and super thin, offering comfortable protection and breathability. It doesn't dig in or sit in an uncomfortable position. We especially love the lacing options. The eyelets are plentiful so you can easily lace your shoes the way you need. They are also placed far enough to really cinch them down if you have a narrow foot, or let them out if your foot is wide. Our only complaint is the laces are a bit short and come undone easily. Switch them out, and you'll find yourself stopping less on the trail.

Dare we say, this shoe will fit most ladies, whether your foot is wide, regular, or narrow. We gave these shoes out to local runners with feet of all different profiles. One of our testers has a large bone spur on the widest part of her foot, and this shoe was accommodating, so much that she bought a pair after running in them once.

Merrell MTL Long Sky - Women's trail running shoes - comfortable and lightweight. what more could you ask for?
Comfortable and lightweight. What more could you ask for?
Credit: Amber King


At only 8.9 oz, it is among the lightest in this comparative review. It feels light on the foot, dries easily, and isn't built for just long-distance training runs but is race-ready. It's hard to find a trail runner with impeccable performance across the metrics, at such a low weight.


The retail price of this Editors' Choice winner is fair and sits right at average as far as trail runners are concerned. We've run in this shoe for over 60 miles, and the only wear and tear we see is along the collar (which is a result of our main testers running style). Aside from that, the lugs have hardly worn, and the upper is doing quite well—an excellent value, considering the price and performance. We expect to get a few hundred miles out of these beauties.

Merrell MTL Long Sky - Women's trail running shoes - take on everything from technical, rocky trails to the road, in...
Take on everything from technical, rocky trails to the road, in comfort and style.
Credit: Amber King


The shoe developers at Merrell have built an impeccable product. It balances all the most important aspects that any great trail runner should have. It's lightweight, stable, comfortable, and quite protective. The MTL Long Sky is designed for all types of trails, covering a range of distances. It features a traditional design (8-mm drop) that'll easily take you from the roads to the technical terrain of high mountain trails. This is a new favorite that's really hard to beat when considering performance and price.

Amber King
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