These lightweight trail running shoes provide great grip, superior lockdown, fantastic trail feel and breathability on hot days - great for speed runs
Ultralight and breathable
Grippy soles with 5mm lugs
Good trail feel
Not much toe protection
May not be the most durable shoe
You can trust Advnture Our expert reviewers spend days testing and comparing gear so you know how it will perform out in the real world. Find out more about how we test and compare products.
Merrell Skyfire 2: first impressions
With the Skyfire 2, Merrell have made their lightest trail running shoe yet and for speed demons, that’s good news. If you’re lacing up for race day, you’ll love the ultralight design of these shoes that boast light, breathable uppers for warm days and supremely grippy soles with deep lugs that look almost like a track cleat. Though they might not exactly bite into the earth the way a spike does on the track, they produce a similar effect, giving you brilliant grip on grass, mud and steep descents while helping to propel you forward with each step. The design of the outsoles means there isn’t all that much rubber covering the midsole, so we can’t see these holding up against regular heavy use, but if you save them for fast days they’ll do the trick.
• List price: $200 / £170
• Gender specification: Men’s and women’s sizing available • Sizes: US: Men’s 7 - 14, Women’s 5 - 11, UK: Men's 6/5 - 14, Women's 3.5 - 8.5
• Lug: 5mm
• Drop: 6mm
• Stack: 25 - 19mm
• Materials: Vibram® MegaGrip outsole, Lightweight FlexPlate, FloatPro Foam midsole, Mesh upper
• Weight (per shoe): 5.6oz / 160g (women’s UK 4)
• Colors: Orange/White/Black
• Best use: Trail running
Forward momentum is assisted by a carbon plate sandwiched into the midsole which provides a noticeably responsive ride even without a maximalist sole. That means you get good protection underfoot without losing too much trail feel, while a conservative 6mm drop means these shoes work for many gaits. Meanwhile, light, breathable uppers don’t provide a lot of protection from stubbed toes or flying scree, but they also mean your feet don’t get hot and sweaty and they dry quickly, which is good because these shoes aren’t waterproof. A socklike fit means you get a really secure fit without having to lace these up too tightly. And finally, we think it’s worth mentioning that these shoes get bonus points for using heaps of recycled materials.
Merrell Skyfire 2: in the field
I recently wrote an article on the three best trail running shoes I’ve tested so far this year, and I’m afraid I may have jumped the gun a little now that I’ve got the new Skyfire’s out on the trail. I’ve had these out on a few runs in recent weeks and they’ve been a revelation now the warm weather is here.
Here’s how they performed:
Sizing and fit
I went up a half size to a 4 as always to give my feet room to swell and at first, I was a little worried I’d made a mistake. Though they felt good on, I can insert a whole finger into the cuff on the inside of my foot. However, the socklike construction makes for a really secure fit; so secure that when I took these off to photograph them on a hot day, I had trouble getting them back on. In short, I think that for some of us, the design means a bit of a weird gap on the inner foot but it doesn’t translate into my foot moving around inside the shoe when I run (though I suppose it could be an opportunity for more annoying pebbles in my shoe).
Once laced up, they’re snug around my midfoot without causing any rubbing and there’s plenty of room in the toe box.
Comfort and breathability
These light shoes offer heaps of comfort, thanks in part to a soft midsole and also to a snug, but not tight, fit of the upper. I’ve experienced no rubbing anywhere in these shoes and was able to wear them for a 10k right out of the box. The breathability is great – you can see the daylight through the uppers – and that of course adds to the comfort. It’s been quite warm here lately and I run in merino wool socks but still haven't found my feet getting too sweaty.
Weight and protection
At 160g per shoe, these are officially the lightest pair of trail running shoes I’ve tested out, which feels great for long runs. The mesh uppers are extremely thin but the main way they’ve saved weight is by only putting the minimum amount of outsole on and leaving a lot of midsole exposed. Overall, I’m guessing this won’t make for the most durable shoe in the long term, but it’s ideal for when you want to move fast and light in warm weather.
If you hadn’t guessed, the upper doesn’t provide a lot of protection against rocks and I did get a painful stone bounce off my foot so I’d be cautious about wearing these for rocky mountain trails.
Responsiveness, grip and stability
The rock plate combined with great flex in the toe means a really responsive run in these shoes, which balance good trail feel with stability thanks to a not-too-high stack. Even though I said I’d be wary of wearing these on rocky trails due to lack of protection, the lugs mean you get great grip even on steep, rocky descents.
Julia Clarke is a staff writer for Advnture.com and the author of the book Restorative Yoga for Beginners. She loves to explore mountains on foot, bike, skis and belay and then recover on the the yoga mat. Julia graduated with a degree in journalism in 2004 and spent eight years working as a radio presenter in Kansas City, Vermont, Boston and New York City before discovering the joys of the Rocky Mountains. She then detoured west to Colorado and enjoyed 11 years teaching yoga in Vail before returning to her hometown of Glasgow, Scotland in 2020 to focus on family and writing.