Article by Jeff Valliere, Renee Krusemark and Mike Postaksi
Merrell MTL Skyfire 2 Matryx ($210)
Introduction
Jeff V: The Merrell MTL Skyfire 2 Matryx is Merrell’s flagship lightweight race shoe with the MTL stands for Merrell Test Lab. It features a Matryx kevlar fibers upper, FloatPro dual density midsole foam, Flexplate and 5mm Vibram Megagrip high performance outsole. It weighs in at just 8.1oz / 230g in my US men’s sample size 10. The Skyfire 2 is a serious contender for any shorter, fast, technical trail races/PR attempts.
Pros:
Light, fast, stable, agile, secure, protection, traction: Jeff V/Renee/Mike P
VERY dialed in fit Mike P
Cons:
Could use a touch more cushioning in the heel, but a VERY minor nitpick: Jeff V
Agree heel is firm, but slightly more rounded than Long Sky 2 Mike P
Lack of cushion (not really a con; for its shorter faster purposes the cushion works): Renee
Not a tight seal around the ankle collar Mike P
Stats
Approx. Weight: men's 7.6oz / 215g (US9) / women's 6.17oz / 175g (US8)
Samples: men’s 8.1 oz / 230g US10 // women’s 6.56 oz / 186g US8
Midsole Stack Height: men’s 25mm heel / 19mm forefoot (6mm drop spec)
Approx Full Stack Height: 31.5mm heel / 24mm forefoot (6mm drop spec)
$210 Available March/April 2024
First Impressions, Fit and Upper
Jeff V: Merrell!!??!! What? I will admit that my exposure to Merrell has been very limited and have not taken the brand very seriously from a trail running or running standpoint as I relate the brand to being a leader in the hiking boot industry.
When Skyfire 2 arrived, at first I thought the box was empty, it was so light. The moment I pulled them out of the box and onto my feet, I was impressed by the no nonsense race ready look and knew this shoe would be a hit. T
he Matryx upper combines multi filament threads of Kevlar and high tenacity polyamide, creating a single layer of material that is lightweight, with better breathability and abrasion resistance.
The Skyfire 2 fits true to size, with a secure heel, midfoot and forefoot, the whole doing an excellent job of providing a flexible, minimal, breathable and secure upper.
While the upper has a very secure and race like fit, there is enough wiggle room in the toe to feel comfortable/not confining and allow for a bit of swell and splay. I have pushed the Skyfire 2 Matryx fast on technical trail descents, off trail, off camber-foothold and stability were excellent.
Breathability is very good, with excellent air flow. The toe bumper is minimal, but offers just enough protection from minor dings, but overall the upper is not very protective and this can be an issue in talus and choss.
Lacing is secure and it is easy to achieve proper lockdown, first try. Merrell also adds a lace loop here that is much higher than all other lace loops I have seen.
At first I was a bit thrown off by this placement, however after a few tries at optimal positioning, I think it makes sense.
The heel counter is somewhat thin and flexible and has an internal strip of padding inside at mid height, yet also is perhaps a bit rigid, requiring a bit of break in.
The padding helps, but is a touch pronounced and not particularly soft. I noticed a bit of rubbing on my heel on one of my very early and super steep uphill runs, but that discomfort seems to have gone away without any real consequence. Softening this a bit though would help I think. The collar height is just right for me, but I do find that the design easily allows in trail debris. I would love to see a light stretch “gaiter” (or higher collar) as the Hoka Zinal 2 has to keep out debris.
The tongue is gusseted in a very wrap around manner, cradling the foot which keeps the tongue well centered and adds to the overall great fit and security of the shoe. To note the inner black linings are treated with 37.5 natural mineral based temperature regulating technology.
Renee: Like Jeff, my running experience with Merrell is limited, and by limited, I mean this is the first Merrell trail shoe I have ever run! The Spring 2024 releases look fantastic, and after running in the Skyfire 2 Matryx (and the upcoming Morphite), I think Merrell’s plan to become a respected brand in trail running is working.
The
The upper is race-oriented in terms of security, yet I found it to be accommodating and comfortable for training runs.
The platform looks narrow, but the fit is not. I have a regular width foot (low volume), but I do like a roomy toebox and forefoot. The balance between a secure trail shoe and comfort with the Matryx Kevlar upper is great. I thought the shoe would feel like a cleat, but it really just disappears on foot while running. My first run was hill repeats in a soybean field (very uneven) and I thought the frozen stalks would pierce the upper. While I did have some damage to the exposed sections of the outsole, the Kelvar upper had perfect protection. Jeff makes a good note about the lack of a toe bumper, but for my terrain, it worked well. The upper is breathable, and when running through snow I could feel the cold (although with wool socks on, it wasn’t an issue).
Mike P: I’m late to this review, and all the fine details have been well covered by both Jeff V and Renee. I’ll be focusing my review on the direct comparisons to the Skyfire’s close sibling, the Long Sky (both new Matryx versions).
I was absolutely blown away by the Long Sky 2 Matryx - especially as it came out of nowhere from Merrell, a trail brand which was not on my radar. I found it to be an amazingly versatile shoe - almost old fashioned in the way that it disappears on foot, doesn’t seem overly fancy, yet produces a fun and fast ride suited for seemingly any trail terrain.
Long story short - the Skyfire 2 takes everything great about the Long Sky, and just dials it up a notch. In terms of the upper - the streamlined, foot hugging Matryx material has been streamlined just a touch, but in all the right places. Midfoot hold is snug like a glove, yet the forefoot shape flares to produce an exceptional, almost custom fit for my foot. The Long Sky upper also has a great fit - but slightly more relaxed in comparison - mainly around the midfoot.
[Left - Skyfire 2, Right - Long Sky 2]
I also notice slightly more taper up front toward the toes, but again, width is maintained across the forefoot, so it’s no issue. Again, just a bit more dialed in.
One area for improvement with both shoes is the heel area. Myself and others have commented that it does seem to be a bit rigid, and could use some more padding or softness on the interior. Interestingly, I find the Skyfire to have a slightly more rounded shape around the heel bone - less vertically straight than the Long Sky, which seems to cup my heel better and feel less rigid.
[Skyfire 2 heel cup is slightly less vertical and more rounded]
Both shoes also leave a bit of space between the ankle collar and the foot - allowing some small debris to get in at times. A knit collar here would be a great and welcome improvement here - something similar to Salomon’s Pulsar.
Midsole
Jeff V: The FloatPro midsole consists of a two part dual density foam that is light, resilient and responsive. Merrell tells us there is no supercritical type foam in the mix. Sitting between the two FloatPro midsole layers is the Flexplate, a BZM-8 Rislan engineered rock plate with we think 8% fiberglass fill, produced from a renewable source. The midsole is light and responsive and with the Flexplate, provide enough cushioning and protection to blunt hard landings on sharp rocks and roots and have enough give for several hours of fast running in technical terrain.
The midsole here is on the somewhat minimal and light end of the spectrum and while not plush by any means, feels surprisingly well cushioned and not harsh or overly firm. It is perhaps a middle of the road density that balances cushion, protection, performance and predictable stability.
Also of note, the footbed is essentially non existent in line with the stripped down, minimal nature of the shoe. I have tried adding a thicker insole in order to add just a bit more cushioning (only because I just want to run in them more and longer), but found that throws off the fit of the shoe and ended up abandoning that idea. If you want a bit more, perhaps opt for the Merrell Long Sky 2, which has that little bit extra you might be looking for. Overall, the midsole feels light, airy and really fun!
Renee: Jeff covers the details. The shoe is meant for distances less than 25k, so the cushion is minimal, but not hard or uncomfortable. The complete underfoot feel is perfect for fast efforts, and I think the shoes work best for “sky” runs or running steep ups and downs. That said, I’m not running rocky, mountain terrain.
I was surprised at how well the midsole and ride worked for hill repeats in a field and on woodland single track trails, which, comparatively, aren't remotely close to the vertical gain of mountain runs. My longest effort with the shoes was 145 minutes, and my feet felt great. I wouldn’t choose the shoes for running on flat, hard surfaces, but for short spurts on that type of terrain, it’s a fast shoe too.
Mike P: The slight stack differences between the two models are interesting - 23.5/19.5 for the Long Sky, and 25/19 for the Skyfire. The 2mm difference in drop is only vaguely noticeable. There is quite a difference in feel though underfoot - I’d say the Long Sky feels noticeably softer and more comfortable underfoot. Even though both forefoot heights are essentially the same, the Skyfire’s Flexplate makes it feel much thinner in comparison. The difference in outsole volume also likely plays a role here in this feeling.
Ultimately, while the Long Sky feels like it can just cruise, I don’t quite get the same feeling from the Skyfire. It wants you to be up on the balls of your feet, minimizing ground contact time, and going fast. Jeff V mentions wanting to run longer in the Skyfire - I agree, and having both shoes in hand, that’s exactly what the Long Sky is for.
Having noticed the Long Sky’s thin TPU insole, I immediately checked for the same in the Skyfire. That’s not the case here - the Skyfire uses a standard foam insole, which is in fact glued down. Just another small detail of separation between the models.
Outsole
Jeff V: The Vibram Megagrip outsole with 5mm lugs provides exceptionally good traction on a wide variety of terrain and conditions. The lugs are aggressive directional chevron shaped and the outsole has a lattice like design with the intention of minimizing weight and perhaps at the same time increasing flexibility (though I think much of that is more influenced by the FlexPlate).
There are also 12 perforations on the top of the lugs (8 in the forefoot and 4 in the heel), presumably to add screws or hobnails for traction. I have not tried this, as I have not found the need given my use of the shoe, but the option is there.
I have been able to test on all my usual Boulder trails, steep rocky technical, off trail, loose off trail and off camber, rock slabs, wet, dry, fresh snow, packed snow and even some icy-ish packed snow and I always felt confident in my footing. So far, durability is proving to be average to above average.
I have some minor damage to the exposed sections of the outsole after running on frozen soybean stalks, but I’ll add that the shoe works great for off trail terrain.
Mike P: In comparison to the Long Sky, Skyfire’s more spaced out lugs in conjunction with the web-like design of the connecting sections do tend to “grab” or “bite” a bit more, especially in soft or loose ground. The Long Sky’s lugs are oriented in a denser grid, leading to a smoother feel underfoot, and also giving the feel of a bit more “effective stack” between the foot and the ground. As mentioned in the midsole section - despite very similar stack heights, the Skyfire just feels so much closer to the ground.
I haven’t racked up as many miles in the Skyfire yet, but I easily put 50+ miles into the Long Sky’s after receiving them. There was hardly a scuff in the outsole, so durability is not a question.
Ride, Conclusions and Recommendations
Jeff V: The Sky Fire 2 is one of the most exciting shoes I have run in in a long time and certainly one of the biggest surprises.
The ride is fast, exciting, lively, dynamic and is overall is just a blast on the trails. They are so much fun despite them being a lightweight racer and on the minimal side, I find myself wanting to run in them all of the time. I’ll definitely reach for them in the future when I am feeling like a spirited run in the range of up to 3 hours (which is about the max for this shoe), and for PR attempts or shorter races.
While the Sky Fire 2 is an ideal pick for going all out fast on a wide variety of mountain terrain, no matter how rugged, I would however exercise caution in loose scree and talus, as the upper is pretty stripped down and offers little protection when mixing the choss.
My longest run in them was a 13.3 mile run over 3 local summits, with over 4,400 feet of gain (and loss). This run had a mix of everything, very steep technical trails, cruiser singletrack, dirt road and some scrambling, with some snow and ice mixed in for good measure. The Sky Fire 2 handled this run perfectly, though by the end of the run (3 hours), I was wishing for a bit more cushion (though I was perfectly fine up till about 2.5 hours).
Merrell has really knocked it out of the park with this shoe and I cannot wait to get my feet in other models of their trail running line.
Jeff V’s Score: 9.8/10
Ride: 10 - for the intended purposes and distances, the ride is amazing! Fast and well cushioned/protected for such a light shoe.
Fit: 9.8 - Amazing secure fit from Matryx upper, but I think heel could be improved a bit.
Value: 9.8 - $210 is pricey, but you are getting exceptional, top of the line, performance
Style: 9.5 - The look is racy, sharp and eye-catching.
Traction: 10 - for such a minimal shoe and design, traction is great everywhere I run.
Rock Protection: 9.5 - for such a light and minimal shoe, rock protection is excellent.
😊😊😊😊😊
Renee: Kudos to Merrell for making a shoe that is fun and exciting. I’m always interested to read what my fellow RTR runners think of shoes, especially if they run different terrain than I do. Jeff is running mountain terrain, and I’m running in fields and woodland single track. The fact that the Skyfire 2 is fun on these varied terrain types is a testament to its design. The ride is exciting, secure, and fun.
The shoe will work best for short, fast efforts especially when inclines and declines are steep or constant. The $210 price is hefty, but with its Kevlar upper, Vibram outsole, and lightweight, I think the shoe is priced comparative to its competition. I’m inclined to say it’s best for racing in mountain/steep terrain, but I enjoyed it for training runs in fields and woodland terrain. For its intended purpose, the Skyfire 2 Matryx is basically perfect.
Renee’s Score: 9.8/10 (-.20 cost)
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Mike P: I think the Long Sky 2 will ultimately work better for most runners, especially considering the price point ($160 for the LS vs $210 for the SF). It’s just a bit smoother, more comfortable, and a lot more versatile for everyday running as well as racing. BUT, if you want to go (very/extremely) fast - for a short-mid distance - it’s hard to beat the Skyfire.
The Skyfire 2 in my US 9.5 weighs in at 7.7 oz (218g) compared to the Long Sky 2 at 8.8 oz (250g). Both are extremely light shoes, but the Skyfire feels even lighter than the 1.1 oz difference - due to its highly enhanced ground feel.
No, you don’t get an overly fancy foam or carbon fiber plate, but it’s a shoe whose Matryx upper just feels like a glove on your foot. At times, it almost feels like you’re wearing nothing at all (on your feet). The heightened sensation of ground feel, without any interference from unstable bouncy foam, or levering plate action, is truly something special and dare I say, unique, these days.
I think this would be a top pick and perhaps ideal for something like a VK, or any type of full-gas short distance event, especially if twists and turns are in the mix, and traction considerations are on the table. Perhaps in some regards this is the “pro” shoe to complement the “elite” Long Sky? However you want to call it, Merrell has hit a home run with both models.
Mike P’s Score: 9.75 / 10
Ride: 10 - Similar feel to the Long Sky 2, but lighter, faster, closer to the ground
Fit: 10 - Slightly more rounded heel cup in comparison to the Long Sky
Value: 8.5 - Quite pricey, but this one is highly performant and specialized
Style: 10 - Gorgeous color design on top of the Matryx upper
Traction: 10 - Megagrip + 5mm lugs + flexibility
Rock Protection: 9.0 - You’ll want to dance in these
Smiles 😊😊😊😊😊
8 Comparisons
Index to all RTR reviews: HERE Roadtrailrun
MTL Long Sky 2 Matryx (RTR Review)
Editor’s Note. Jeff and Renee did not test the Long Sky. It weighs 8.6 oz / 244g (US9) so 1 oz /28g more, we assume mostly due to its fuller coverage outsole but also maybe due to a different FloatPro foam. It shares a Matryx upper with the Skyfire.
It has a 1.5mm lower heel and 0.5mm higher forefoot, so it is a 6mm drop shoe. It has no nylon plate as the Skyfire has and has a single density foam midsole. Its platform is almost identical with only the midfoot being 5mm wider. At $160 it is $50 less expensive than the Skyfire. Mike Postaski in his review scored them the same Jeff and Renee did the Skyfire 2 at 9.8 /10.
Mike P: Compared closely throughout my review - see above. Sizing is the same for both models, with the Skyfire being just a bit more dialed in. Neither shoe is for wide feet, the Skyfire especially so. Both have excellent forefoot fit though. The Long Sky can do practically everything, and the Skyfire is a speedster focused on shorter stuff. If I had to pick I’d recommend the Long Sky based purely on versatility. Both shoes are amazing.
Hoka Zinal 2 (RTR Review)
Jeff V: The closest comparison I think, the 2 shoes are very close in weight with advantage going to Sky Fire 2 as they have comparable fit, security, fast/nimble/agile performance, traction, etc…
The Sky Fire 2 offers a bit more performance I think, with an edge in response, a little better traction and is a little more adept in technical terrain with better protection and cushion underfoot. The Zinal has a slightly more protective upper and I LOVE the snug stretch mesh around the ankle collar to keep debris out. Not sure why all trail shoes do not have this? Zinal is $30 less.
Salomon S/Lab Pulsar & SG (RTR Review)
Jeff V: Aside from the Pulsar SG being lighter, I cannot think of any reason to pick it over the Sky Fire 2. The Pulsar SG does have a more glove like custom feeling upper, but it is really snug and unforgiving for all but the shortest runs with no leeway for wiggle room. Because of its lower weight, the Pulsar SG might be a slightly better choice for all out uphill efforts, but if you have to come back down (which we often do), the Sky Fire 2 has better traction, better cushion, better protection.
Mike P (9.5): I have the original (gray, V1) Pulsar. Similar, snug, race fitting uppers for both shoes. But the Pulsar is a bit narrower at the forefoot and really a tight squeeze. The Skyfire upper is more “shapely” around the forefoot, yet still wraps like a glove. The Pulsar does have more cushion giving it more distance range, if you’re a lighter runner. But it’s higher off the ground, giving the Skyfire the edge in stability and overall ground feel. One thing the Skyfire and Long Sky could steal from the Pulsar is the well-fitting knit ankle collar.
Salomon Pulsar Pro 2 (RTR Review)
Jeff V: Much of the above comparisons on the S/Lab Pulsar SG holds true, though the Pulsar Pro 2 weighs a good bit more and despite having more cushioning, the cushioning is hard and unforgiving. I will also mention that the Pulsar Pro 2 feels particularly tippy with the inflexible plate and narrow heel.
Mike P (9.5): The Skyfire is so good, this is not really a fair comparison. The Pulsar Trail Pro 2 has more cushion, and a nice, wide forefoot, but it’s a very stiff ride. I don’t feel safe in technical terrain in them, and generally prefer a more flexible ride. I think the Long Sky is a closer comp, and the Long Sky wins by a mile.
VJ Spark (RTR Review)
Renee: Both shoes are meant for short, fast distances and have a look that reminds me of a cleat. The Skyfire 2 is a much lighter shoe. Sizing is comparable, although the toebox of the Spark is a bit shallow. The midsole of the Spark has a bit more softness, but still not enough for long distances. Overall, the performance of the Skyfire 2 is better, albeit at a much higher cost.
Jeff V: Agreed with Renee, but I think the Sky Fire 2 has better cushioning and protection underfoot, at least on the rocky terrain I frequent. Spark has a better outsole with even better traction.
Mike P (10.5): Agree with Renee - similar cleat-like outsole design. The Spark does get a slight edge in grip and traction. I also find the shape of the shoes to be similar, but the Skyfire’s Matryx upper seems like it has about 5 less layers than the Spark’s. The Spark is missing something around the midfoot, and transition is a bit lacking on the run. It really feels more suited to OCR type stuff than true running.
VJ XTRM 2 (RTR Review)
Jeff V: See Spark comparison above. While the XTRM 2 is a better shoe IMHO than the Spark, many of the same comparisons hold true.
Mike P (10.5): I like the XTRM 2 over the Spark, but it’s such a burly and heavy shoe relative to the Skyfire. I’d go with the XTRM 2 for extremely rough, off-trail, jagged rock type stuff, but the Skyfire wins in anything remotely close to actual running.
TNF Vectiv Sky (RTR Review)
Jeff V: The Vectiv Sky is not as light, nor is it as agile or adept in technical terrain and although it has a similar stack and fit and feels more firm and less forgiving, maybe due to its carbon vs the nylon plate of the Sky Fire. The Sky Fire 2 is quicker overall, more responsive and has better traction.
Mike P (9.5): The TNF feels blocky under the midfoot, and you get lots of impetus from the plate as well as the rocker design. That’s the big difference between the Vectiv and both the Long Sky and the Skyfire. There’s no such technologies getting in the way with either shoe, leading to a much more pleasing ride. I’d say the Long Sky is more comparable than the Skyfire, and I’d go with the Long Sky all day.
NNormal Kjerag (RTR Review)
Jeff V: Close in weight, fit, comfort and performance, both are great options for fast trail running/racing. The Sky Fire 2 I find to be a bit more protective with the plate and for sure has better traction and I think a bit more responsive uphill.
New Balance SC Trail (RTR Review)
Renee: The SC Trail has a carbon plate and is a higher drop shoe at 10mm vs. 4mm for the Sky Fire. For runners needing more cushion, the SC Trail might work better (the shoe is heavier, but still light weight for a trail shoe). The Skyfire 2 is the better choice for rugged terrain or steep inclines and declines. The plate of the SC Trail will help with speed on mellow terrain (while not being unstable elsewhere despite the high drop). Sizing is comparable.
Jeff V: Agreed with Renee on all points.
The Skyfire 2 Matryx will be available March-April 2024
Renee is a former U.S.Marine journalist, which is when her enjoyment of running and writing started. She isn’t that awesome of a runner, but she tries really hard. Most of her weekly 50-60 miles take place on rural country roads in Nebraska, meaning mud, gravel, dirt, hills, and the occasional field. She has PR’s of 1:30:59 for the half marathon and 3:26:45 for the marathon.
Mike Postaski currently focuses on long mountainous ultras - anywhere from 50K up to his favorite - 100M. 5'10", 138 lbs, midfoot/forefoot striker - he typically averages 70 mpw (mostly on trails), ramping up to 100+ mpw during race buildups. A recent 2:39 road marathoner, his easy running pace ranges from 7:30 - 9:00/mi. From 2022-23 Mike has won the Standhope 100M, IMTUF 100M, and Scout Mountain 100M trail ultras. He also set a CR of 123.74M at the Pulse Endurance Runs 24H and completed the Boise Trails Challenge on foot in 3 days 13 hours, besting the previous record by 7 hours. Mike's shoe preferences lean towards firmer, dense cushioning, and shoes with narrower profiles. He prefers extra forefoot space, especially for long ultras, and he strongly dislikes pointy toe boxes.
Samples were provided at no charge for review purposes. RoadTrail Run has affiliate partnerships and may earn commission on products purchased via shopping links in this article. These partnerships do not influence our editorial content. The opinions herein are entirely the authors'.
7 comments:
Jeff V- You also noticed the lace loop - I liked the higher placement in the Long Sky 2 as well.
It's so frustrating cause we know they are a banger but we have to wait....
I have heard these run a half size big, but the review says true to size? I am size 10. Should I stick with US 10?
Definitely go true-to-size. I've got a perfect fit in my TTS US 9.5. That goes for both the Long Sky 2 and Skyfire 2 Matryx models.
If anything, I'd say they're more on the snug & secure side as opposed to running big.
hi! any chance you could tell us about your foot lenght, mike or jeff? that would also help in a lot of other reviews to judge the sizing
I'm 26.5 cm, size 9.0 (barefoot) on one of those standard foot scales in the stores
thank you so much for the quick response - that helps a ton!
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