Merrell MTL Long Sky Review

Merrell Test Lab (MTL) recently came out with a really well-designed, 8mm drop, cushioned, all-purpose trail shoe that feels equally at home on a muddy and rooty forest path, a rubbly Arizona desert trail, or on Rocky Mountain singletrack with patches of ice and snow. In collaboration with Anna Frost, MTL brought life to the vision of a performance shoe that would be appropriate for any ultramarathon distance (or shorter, of course) over ever-changing terrain regardless of the weather. The Merrell MTL Long Sky ($130) definitely hits the mark even down to the vibrant color ways and Vibram Megagrip lugged outsole. This shoe is comfortable out of the box and ready to go wherever you’re heading to run. It’s so good that it might be a strong contender for the only pair you pack if you’re heading out for a running adventure/vacation and you want to stick with just one carryon. At 8 ounces/230 grams for each of the women’s shoes and 10 ounces/280 grams for each of the men’s, they won’t push your carryon overweight either.

Of course, all this hinges on the fit being right for you. It’s not the widest shoe in the world, but the width of the forefoot and snugness in the heel fits my foot shape well (like a Birkenstock) with the exception that perhaps it could be just a bit wider across the toes to play to a larger audience. With the accommodating upper and highly adjustable lacing system, there’s room for expansion in the shoe to ensure comfort throughout a long day in the mountains. All in all, I think Anna and Merrell did outstanding work creating the Long Sky.

The Merrell MTL Long Sky. All photos: iRunFar/Bryon Powell

Merrell MTL Long Sky Upper

The upper of the MTL Long Sky is constructed with a lightweight, wear-and-tear0resistant, large-pore mesh with a layer of thin but protective thermoplastic polyurethane (TPU) reinforcing the toe area and extending toward the midfoot medially and all the way through to the heel laterally which supplies a bit more structure in these regions. The TPU also creates adequate protection with the flexible toe cap at the front of the foot from those pesky rocks and debris lying in wait. The molded TPU heel counter is on the firmer end of the spectrum and is very supportive. I find it keeps the shoe well connected with my foot. A reinforced loop attaches to the heel making it easy to slip the shoe on as well as clip via a carabiner to a crew bag.

A thin layer of similar reinforcement surrounds the lacing slits where the lace routers attach to the shoe itself. Though the laces themselves can sometimes come undone, the actual lacing pattern and structure is reliable and easy to specifically adjust to one’s own foot. I just have to be assertive in pulling double knots tight to keep them laced for the duration of my run. Overlying the upper along the lateral aspect of the mesh is the Merrell logo in relatively large, highly reflective capital letters. I was surprised how much they glowed under the light of an oncoming bike headlamp.

The tongue is gusseted completely and seamlessly links to the soft mesh inner bootie. It’s the perfect length toward the ankle tendons and unobtrusively stays in place. Though the tongue’s thickness isn’t significant, the density of the material does a great job of protecting the foot from the laces and adding security to the fit. The soft mesh inner lining extends up through moderately padded ankle collar and makes no-show socks an option simply due to the comfort. The Achilles tendon and ankle-bone notches are relatively low-profile and don’t protrude into my bony parts regardless of how wild I’m getting on the doll-head rocks.

For me, this upper is really just a pleasure to wear, particularly as the weather warms up. The large pores make the shoe extremely breathable on hot days but sand and dirt definitely have a way in. When I race in these shoes, I’ll be sure to have a breathable gaiter on over top. I wore the shoes in some wet, spring snows (the winter that wouldn’t stop) simply due to the incredible traction they provide, and my feet were soaked and numb within 15 minutes. They didn’t have much chance to thaw or dry out until after I was home simply due to the heavy, wet snow. While the Long Sky dry quickly in warmer weather after a good stream crossing—they excel in that, actually—but in 17 degrees Fahrenheit, the dry-out period required a full day on a nice shoe mat inside a warm house. Obviously winter snow and slush conditions weren’t what they were designed for, but I wanted to include both ends of the weather spectrum.

The Merrell MTL Long Sky lateral view.

Merrell MTL Long Sky Midsole

Merrell utilizes a relatively dense ethylene-vinyl acetate (EVA) foam midsole with light pronation control via a subtle medial post. I’ve never noticed the added support during my running, but over the course of a tough 50k or 50 miler, I think its presence would simply lessen the fatigue and encourage a more neutral stride in the later miles. Though there’s no rock plate within, the relatively firm cushioning coupled with the excellent lugged outsole combine to keep my feet bruise-free even on rocky Colorado trails. The resilience of the midsole compound is pretty impressive because these shoes have almost as many snow/cold days as warm/dry days in the 200-plus miles I’ve run in them. The Long Sky really is a comfortable long-distance shoe but, at least for me, it’s snappy enough that I can feel “fast and agile” on my shorter runs.

The Merrell MTL Long Sky medial view.

Merrell MTL Long Sky Outsole

The outsole is constructed of 5mm multi-directional lugs constructed from Vibram Megagrip which is a marvelously durable compound that facilitates traction on about any surface. The lugs grip varying densities of snowpack well when I hit the snowfield across my favorite mountain trail while still making me feel like I’ve got control and purchase on all but the worst clay-mud. The lugs shed regular mud quickly and maintain grip even when rocks and roots are wet. I’m comfortable in the Long Sky ascending and descending the rubble so common to our area, but I also am able to feel a smooth ride on the dirt singletrack out my door that isn’t exciting in the least except for the fact all trail is enjoyable and lovely most days. The ability to be comfortable in this aggressive outsole on such a wide spectrum of trails is perhaps also thanks to the break in the outsole between the back of the midfoot and the start of the heel. It allows for some decoupling in the shoe such that it is free to conform just like your foot does to the terrain it’s on whether more or less challenging. It’s a well-designed outsole that, again, allows the shoe to really excel in almost every type of trail running.

The Merrell MTL Long Sky outsole.

Merrell MTL Long Sky Upper Overall Impressions

Just like the color of the shoe I received (Exuberance = orange), I do feel a certain exuberance when I lace up these shoes to head out for some hours on the trail. It’s just plain fun when you can throw on a pair of trail runners and really not think much more about them for the duration of a run. I love that I can powerhike steeps, rattle and clatter down declines, try to pick up my pace in the smooth sections, and lumber along when my plans outshine my fitness level. These shoes will be accompanying me on many more runs before they are retired (around 200 miles in them thus far), and then I’ll be buying another pair wherever I can find them. Anna and Merrell, I look forward to your next collaboration!

Call for Comments (from Meghan)

  • Are you running in the Merrell MTL Long Sky? If so, what are your overall impressions of it?
  • What do you think about the overall fit and make-up of the upper?
  • How does the outsole work for you and in what conditions are you using it?
  • What other details can you share about running in the Long Sky?

[Editor’s Note: If you’re affiliated (i.e., an employee, ambassador, etc.) with a brand, please share your relation in each of your comments on this article. Thanks!]

The Merrell MTL Long Sky top view.

Kristin Zosel

is a mom, wife, ultrarunner, physical therapist (on sabbatical), and transcriptionist for iRunFar.com. Her love of steep uphills, high mountain environments, and Swiss “lovely cows” keep alpine visions dancing in her head and strong cappuccinos in her mug.

There are 3 comments

  1. Scott Gater

    So far I like them. The sole is very grippy and for east coast runs in mud and roots, they are by far the best outsole I’ve used. They are just wide enough in the toe box to be comfortable. I dislike the huge/very wide toe box, so these fit very well. The laces are not the best at staying tied, which seems odd, but in the wet, they seem to come undone more than I would think they should, especially if I’ve double knotted them.
    A solid 8 out of 10 for me.

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