The SLAB Ultra is a maximum feature trail shoe by Salomon that is built to take on any trail and any distance. The SLAB Ultra is built on a stable platform with an 8mm drop, and provides two layers of underfoot protection with Profeel Film and a TPU insert. The SLAB Ultra has a unique decoupled upper that uses four Sensi-fit wings on each shoe for lateral support. I’ve been wear testing the SLAB Ultras for the last few months, and recently walked the 150-mile Camino Portuguese in them. I have put close to 250 miles on this shoe and will share my thoughts in this review.
The Salomon SLAB Ultra is a very different shoe than the similarly named Salomon SLAB Sense Ultra. If you loved the SLAB Sense Ultra, be prepared for a very different fit and on-trail experience with the SLAB Ultra. The SLAB Ultra was designed with input from Salomon athlete Francois D’haene and is the shoe he won during his Ultra Trail du Mont Blanc 2017 victory and his John Muir Trail ‘fastest known time’ effort.
Fit and Feel
Sizing and Weight
I wear a size 12 in the SLAB Ultra, which is the same size I wear for the XA Elevate and Sense Ride. The SLAB Ultra has a similar fit to the XA Elevate, but with a little more length overall and a slightly more tapered toebox.
My size 12 US of the SLAB Ultra comes in at 12.4oz, which is a lot lighter than I thought they would be when I first saw this shoe’s feature set.
The toebox is a little narrow on the SLAB Ultra, but this hasn’t been much of an issue for me since the shoe also runs long. Lengthwise, I could have probably gone with an 11.5, but at that size the toebox felt like it could become an issue. While walking the Camino Portuguese, I had consecutive days of big uphill hikes followed by foot pounding cobblestone paths into town. I’m glad I stayed with the size 12, because when my feet began to swell, the size 12 was perfect.
This is also a toebox that gets better with time. Salomon uses a flexible plastic laminate on the upper of this shoe that feels a little stiff at first. After 20-30 miles the upper starts to break in and get more comfortable. Mine started to feel like a soft glove once I passed the 50-mile mark.
The midfoot of the SLAB Ultra fits much like the XA Elevate, slightly tight at first, but really nice once broken in. Much like the rigid Sensifit lateral support found on the XA Elevate, the support wings on the SLAB Ultra take some time to break in. Before walking the Camino Portuguese, I broke in my pair of Ultra’s with a mix of trail running and hiking. I was initially worried that the midfoot fit was too tight, but quickly realized I just had to dial in the lacing. Unlike the quick lacing on many of the other Salomon shoes that I own, the SLAB Ultra allows for more varied tension from top to bottom.
The heel fit on the SLAB Ultra is a bit off for me. It could be that the shoe really is too long and I need to size down, but I think the heel width is more than my narrow heels prefer. Even when I have the lace tension at full cinch, I get a tad bit of heel slip at toe off. This has improved a little as the thick and firm midsoles have broken in, but not as much as I would like.
The heel area on the uppers of the SLAB Ultra are thin, malleable, and have no counter. This makes for a very comfortable fit, just not the most precise for my foot shape. I haven’t had any blisters or hotspots on my heels though, so I won’t complain about this too much.
The upper on the SLAB Ultra uses a breathable anti-debris mesh for it’s base, with a laminate overlay on top to provide additional protection. I was surprised how well this upper breathed on hot days reaching triple digits towards the end of my pilgrimage, and on a few hikes here in Southern California. I also had three days of rain on the Camino that soaked the SLAB Ultras straight through. They drained really well when submerged and were dry and ready to go each morning.
Long time Salomon fans will be glad to hear that the SLAB Ultra has a top-loading lace garage for the quicklaces! This may seem like a small thing, but it makes a big difference for quick adjustments on the fly. The comfort and performance of the Endo-fit/Quicklace combination is excellent, just as I’ve come to expect from all of my Salomon trail shoes.
So far the durability has been great, without any premature seams, tears, or holes as I approach 250 miles.
The standout feature on the uppers of the SLAB Ultra are the stability wings. I wasn’t quite sure what to make of these wings when the shoe was first announced. Now that I’ve used them, I’m a huge fan of the support they provide, but am still not sure why they need to float above the shoe. It would be preferable if they were welded to the upper of the SLAB Ultra like all other Sensi-fit support systems. There were a few times when rocks or pebbles would get stuck in the gap. Not a huge deal, but probably avoidable.
The midsoles on the SLAB Ultra are simply amazing. Salomon uses a firm and stable EVA for the base of this midsole, with 26mm in the heel and 18mm in the forefoot. At the base of the forefoot, Salomon uses a visible PU insert. PU is denser than EVA, making it more stable and more protective. In between the PU insert and EVA top bed, Salomon adds a Pro-feel film insert for additional underfoot protection from rocks and sharp surfaces.
Having used the SLAB Ultra on rocky trails, talus fields, dirt roads, and cobblestone streets, I can say that this is the most dynamic midsole I’ve ever used. The protection underfoot is enough for the roughest trails you’ll come across, and yet the shoe still has the cushioning for comfortable miles on asphalt and hard pack. This really is a Goldilocks midsole.
I’ve been wearing this shoe as a trail runner with no pack, as a hiker with a kid carrier, and on a pilgrimage with a 15lbs backpack. I never once felt that the midsole was too much cushion or too little cushion on any of those outings. Over 10 days, I averaged around 15-miles per day walking from Porto to Santiago de Compostela. Each day my legs and feet felt fresh, healthy, and easily capable of walking 25-30 miles. My daily distance at home tends to max out around there, but I have no doubt that these would perform very well for those that cover ultra distances.
At 250 miles, the midsole still has a ton of life left. I tend to wear midsoles out in the forefoot, but the durable PU insert on the SLAB Ultra seems to be balancing things out. This is easily a 400-500 mile shoe for me, and could go much further for those that weigh less than my 180lbs.
If it isn’t broken, don’t fix it. I’ve raved about Salomon’s latest outsoles on the XA Elevate, Sense Ride, Sense Ultra, and other models. This Premium Wet Traction Contragrip outsole paired with a trapezoidal lug pattern performs well on all surfaces. I’ve taken this shoe on steep rutted downhills, muddy sidehills, slick granite, and sandy washes. In all cases, this outsole just works.
At 250 miles, you can see the lugs on the lateral side of the heel are almost gone. I’ve worn this shoe on a lot of asphalt and cobblestone through Spain and Portugal though, and I don’t think I’d see this wear for strictly trail use. Still, the tread in the forefoot area is still looking brand new.
The Salomon SLAB Ultra has been an amazing performer for me, both on the mountains here at home and on the trails through Spain and Portugal. The midsole can handle any distance and keeps my legs feeling fresh and spry. The outsole provides excellent grip and traction on just about any surface. The uppers provide ample stability and protection while still remaining breathable. I just wish the fit through the heel was a little more precise for my foot shape. At $180, the SLAB Ultra isn’t cheap…but anyone looking at Salomon’s SLAB footwear will already know this. Salomon’s SLAB shoes offer maximum performance with minimal weight. If you find yourself seeking some of the best trail shoes money can buy, you’ll want to give the SLAB Ultras a close look.