Monday, August 07, 2023

Salomon S/Lab Ultra FDH 2023 Review: François x Salomon 7 Comparisons

Article by Sam Winebaum

Salomon S/Lab Ultra FDH François x Salomon ($240)


The S/Lab Ultra François x Salomon is an all new ultra trail focused shoe originally designed for the needs of Salomon athlete François D’haene, a 4 time winner of the UTMB and many other tough ultras including Hardrock 100 in 2021. 

In contrast to his former team mate Kilian Jornet who raced minimal in Sense and Pulsar, François  has always gone for denser cushioning, more protection, and stable rides. The original “Ultra” and 2 subsequent editions, all tailored to his needs and to an extent to his narrow foot, have been his shoes of choice for all his recent victories until he started testing the new Ultra.

So enter the next generation of Ultra, an all new shoe with a big stack height so more cushioning than prior Ultra and with Energy Foam instead of the prior and firmer EnergyCell foam and a somewhat flexilble fiberglass protection/propulsion plate. The upper is Matryx in a very light mesh and we have the usual 3.5mm lug Contagrip outsole.  

Extensively tested and iterated over the last couple years, it joins 3 other Salomon in the ultra/distance category: S/Lab Genesis, the prior Ultra (3) staying in the lineup, Ultra Glide, and the new Glide Max TR. In the article, I will give you my take on the Ultra how it has performed trail running more mellow trails and some road and hiking paces on extremely rocky rugged terrain in the White Mountains of New Hampshire. 

I also compare to 6 other similar shoes including all the current Salomon long distance shoes at end of the article.


  • About as protective a trail shoe as I have ever run with lots of not overly firm cushioning and rock protection

  • Smooth and friendly at all paces from power hiking to flat hard surface running 

  • Fiberglass plate is a better choice than carbon: clear propulsion, some flex, not harsh at any pace, protective

  • Energy Foam gives plenty of stable and consistent rebound/return.

  • Any surface, any distance versatility: ideal shoe for the longest of hauls yet can also do short and quicker, and this despite its weight 

  • Matryx upper is adequately secure and airy and accomodates up to medium volume feet as mesh is light and pliable

  • Particularly well executed QuickLace: easy to store, variable areas of tightness adjustment and stays that way.


  • Somewhat heavier than ideal at 10.3 oz / 292g but we have a big 39/29 stack height, plate and a full outsole. 

  • Big forefoot stack and springy if flexible plate along with relatively narrow midfoot platform and light upper make it not as stable/ground conforming upfront on sharp off angle rock obstacles as would be ideal or as other big Salomon shoes. 

  • A more substantial heel counter for more tech terrain and to better lock the light upper to the foot is in order along with potentially some midfoot underlays

  • Pricing at $240..Supercritical foam to lighten and give more energy return would make it a better value. 


Sample US men’s 9: 10.3 oz / 292g (10.48 oz / 296g right, 10.21 oz / 289g left) 

Stack Height: men’s 37 mm heel (measured) / 29 mm forefoot ( 8mm drop spec) 

$240  Available August 8, 2023 at Salomon HERE

First Impressions, Fit and Upper

Sam: No surprise the upper is Matryx and it’s lightweight and breathable. The mesh has Kevlar fibers in the mix for durability and to lighten the upper. Salomon S/Lab loves Matryx for these characteristics and here it is the lightest and thinnest Matryx I can recall on any shoe.

I guess you could say the surprise is the colorway here. No S/Lab red beyond the quick laces and tongue logo and not even the black of the prior Ultras with here a grayish blue mesh with thin longitudinal green fibers which I assume are the Kevlar. 

The overlays are navy blue on the lateral side with the big full rear overlay an avocado green which on the medial side starting as a lighter green blue than the lateral side. 

It ends up in one word, classy and simple, and a conservative design which stands up to dirt really well.

Of course we also have a bit of a billboard on the lateral heel with Francois X Salomon and the tagline “Born of a decade of shared vision”. No question whose S/Lab shoe this is! And the S/Lab is dedicated first and foremost for creating shoes and gear to the particular specifications and needs of Salomon athletes in all sports with wearable usable prototypes created at Salomon’s Annecy Design Center. I was lucky to visit it in 2019 and in house indeed everything can be made: molds, midsoles, uppers, and apparel. 

The mesh itself is far more pliable than the Ultra 3, thinner and more open. Compared to the Genesis the mesh is also thinner, a touch less dense and more pliable. The mesh is single layer (other than the gusset) and completely unlined, including upfront, but for the overlays. The shoe is very breathable and decently draining and drying but the full lower rand overlays for durability and support are a factor in draining.

While one cannot say it is a broad fitting shoe, the mesh and unstructured toe box with and extensive but pliable toe bumper make the fit accommodating for sure for narrower to medium feet but this is not the high volume somewhat stretchy upper of the Ultra Glide 2. 

The quicklace and tongue is particularly well done. 

The gusset tongue is a dense almost neoprene like mesh with a small pad behind where the quick lace sits. 

Unlike most quick lace garages, here we have top loading one that is far easier to use than the usual bottom loaders where laces are often in the way of stuffing the laces and clip in.

I will highlight that lace up is super effective with some ability to have different tensions along the length of the lacing and I have never had to readjust much even after miles of wet feet on off camber rocks.

We have more changes at the heel. The heel counter is more pliable than either the Ultra 3 or the Genesis as here and in both of those there is no internal heel counter I can detect. 

All rely on an external heel counter or overlay and here it is a single uninterrupted panel of leather like overlay extending around the heel, up to the lace up and along the rand all the way to the front. 

At the front the single layer creates the top layer of the toe bumper with what feels like a second thin layer up front but no stiffeners. 

The toe bumper is similar to the Ultra 3 and Genesis but a bit more extensive in coverage over th toes for lockdown given the super pliable main Matryx mesh which is thinner and more pliable than the usual from Salomon. 

Back to the heel area. The top edge is more conventional than S/Lab 3 or Genesis in not having a knit collar but having a lightly padded more rolled top edge. 

I do think more debris sneak in more than in the other S/Lab with their knit collars as I got some small sand in during my hike test.The inner padding around the achilles and first part of the ankle are thin, dense and similar to the other S/Lab ultra focused shoes.

Rear support is adequate but I do wish for a touch more of it to control lateral motion. I did find less play than in the Genesis (which has a broader rear and midfoot volume) and which, unlike my half size up Ultra is true to size. My half size up Ultra 3 is clearly more secure the heel. 

In terms of fit my pair is a half size up from my normal and fits my narrower to medium fits well and comfortably. Here in the new Ultra the more relaxed mesh and overlays up front are really an improvement in comfort even though the shoe remains not the widest. This said in a pair I would go true to size to potentially improve overall hold. And I think the fit would be further improved by bringing back the internal underlays of the Ultra 3 and its stretch knit tongue and rear collars.

I have not taken them to great distances yet, beyond a 6 hour hike on very technical terrain and I had no issues beyond a single moment when I felt my small toe was being pressed a bit hard. I will note the Ultra 1 had big issues for me and my fellow tester Jeff Valliere at the smallest toe. Way too tapered. And we know Francois has a very narrow foot. This is a much more toe friendly fit due the upper materials and front volume.


The midsole is Salomon Energy Foam EVA / Olefin copolymer block compound in a single density as far as I can tell. It is very forgiving without being overly soft. I suspect it is the exact same foam as in the Genesis and Ultra Glide but not the Glide Max TR which to me is more energetic with the shoe lighter and at a higher stack height.

There is lots of cushion here with a 37 mm heel / 29mm forefoot stack height with protection and propulsion from the plate. It is clearly softer than the Ultra 3 and not quite as soft as the Genesis but more energetic in ride overall.  I will cover in more detail in Comparisons but the Max Glide TR is slightly more cushioned in stack and on foot in feel but lighter as well. 

In the mix, and in a big change from the Ultra 3 and Genesis, is a  ProFeel “ground filter” fiberglass plate. Yes, not carbon and while maybe a bit heavier than carbon I think it is a good call. 

The plate is moderately propulsive and has a long flex, so not totally rigid and for sure not as rigid as the Pulsar Pro Trail with its stiff fiberglass plate.  Its flex is unlike either the more flexible and easy flexing Ultra 3, also a long flex or the Genesis which has a snappier front flex point. I found the Genesis climbs steeps slightly better as does the Ultra 3 with the new Ultra having distinctly more front cushion than either and I would say also propulsion due to the plate and especially so on smoother moderate terrain up, down, or flats.  

The downside, and a small one, is they are not as ground conforming up front and I found a bit tippier on sharp angled rocks than either of the other two S/Labs. 

At the heel the cushion is deep and there is a decisive sensation of “planting” of the heel on landings as we have a 90mm wide heel platform and 34mm of stack and that is followed by an easy transition through the a relatively narrow 70mm midfoot to the plate and front. They power walk well although the front flex of the others, their lower stack heights and slightly narrower front platforms (105mm for Genesis and Ultra 3 with 110 for the Ultra)  make them somewhat better climbers on steeps and slightly more stable overall with their more secure uppers are also taken into account.


Nothing particularly special about the outsole. It’s Salomon’s Contagrip with 3.5mm lugs.  The Genesis has 4.5mm lugs while the Ultra 3 5mm lugs  It appears to be the usual Contagrip although it may be a touch softer than the rubber in the Genesis and Ultra 3. 

There are 6 front cutouts to the plate to help with flexibility (Genesis and Ultra 3 have none), and they are effective giving the Ultra a smooth ride on harder smooth surfaces, even road. I have not noticed pebbles stuck in the cutouts. 

Within a week I took the Ultra, Salomon Thundercross (also with Contagrip) and boots/shoes with Vibram MegaGrip and VJ’s Butyl rubber in higher lug heights on the same rugged rocky hiking terrain and with similar wet rock conditions.  

I found a bit more occasional slipping on wet gritty rock with both the Salomon than with the others. Not a big issue as overall the outsole here is very versatile handling the more technical but also smooth and even roads better and with less “noise”.

Ride, Conclusions and Recommendations

The S/Lab Ultra takes Salomon top distance racing shoe into the land of max and softer cushion and plates “daring” to be different. Instead of carbon they go with a friendlier and flexible yet still very protective and propulsive fiberglass plate. Maybe Francois tested versions with carbon and chose this more long distance and I would say slower paces suitable approach.  

The ride is highly cushioned, decently soft and reactive and most of all protective especially at the forefoot while never getting bogged down or mushy given the big stack and even at slow paces or for that matter getting over firm and harsh as carbon plated shoes can. 

The very light, breathable and pliable Matryx upper is comfortable, adequately well held and as with the ride designed for long long hours on trail. I do think the rear construction and heel counter could be stouter/less pliable and tie in better to the lacing as its predecessor did and the midfoot might benefit from a touch more support than the gusset tongue as there are no underlays or underlays and no stretch knit construction of tongue and rear as before which was also a benefit in keeping out debris.

At $240 one might say: “Wait. No carbon plate, only fiberglass?”  I am OK with the fiberglass plate as it is more friendly in flex and feel than carbon might be and especially at relatively slower ultra paces. I do think value does suffer due to weight as at 10.3 oz / 292g one would think such a pinnacle shoe would be lighter as its key competitor the $225 Hoka Tecton X is while, while the that shoe is also slightly lower stack and carbon plated.

Value on the other hand is improved from that starting point by the “deep” versatility and protective ride of the Ultra. It has plenty of kick and get up and go while totally protective and comfortable underfoot and up top.  Head out the door on any surface at those ultra type paces and you can imagine going on nearly forever! Or pick up the pace and it can kick into high gear.

Sam’s Score: 9.32/ 10


Ride (30%): 9.4, Fit (30%): 9.4, Value (15%): 8.5,  Style(5%):9

Traction(15%): 9.2 Rock Protect(10%):10

7 Comparisons

Index to all RTR reviews: HERE

Salomon Comparative Chart

Salomon S/Lab Ultra 3 (RTR Review)

The Ultra 3 has been Francois (and Courtney Dewalter) go to ultra shoe. Francois has moved to the new Ultra and Courtney to the Genesis in recent races.  The Ultra 3 is a big 8mm lower in stack and has firmer more responsive EnergyCell foam. Its front protection is a dense PU insert.  It weighs slightly less than the new Ultra and sits on a narrower platform. 

The new Ultra is clearly more cushioned with an easier sense of front propulsion from its plate.The Ultra 3 is more flexible. It is more stable particularly upfront and overall and with more ground feel. The Ultra 3’s Matryx upper is denser and has both a knit bootie tongue and rear wrap and overlays at midfoot. It has a more secure upper than the new Ultra,  Its heel is more stable and midfoot more securely held. 

I am a half size up in both and the new Ultra due to its lighter mesh and less extensive upper construction is clearly a more ultra roomy fit, if I think on the same last and with the same basic volume. The Ultra 3 remains in the line for good reason. It is a better go to for more mountainous runs while the new Ultra is a better S/Lab choice for longer less technical terrain.

Salomon S/Lab Genesis (RTR Review)

The Genesis is the lightest S/Lab ultra oriented shoe at 265g / 9.35 oz so weighs about 1 oz /28g less than the Ultra. That said, it sits on a 7mm lower heel platform that is also somewhat narrower on the ground than the Ultra. Originally designed for Ryan Sandes who has a very broad midfoot, like the Ultra 3 it has a stretch knit tongue/bootie construction and TPU side panels that adapt to different rear of foot widths. Its front upper is slightly broader in fit as well, even if its Matryx mesh is notably denser. I am true to size and just fine in them but find the rear width a bit much with the heel hold sitting between the Ultra 3 and new Ultra. 

Underfoot we have a softer if slightly less cushioned ride than the Ultra with no plate but ProFeel film with the Genesis having a more pronounced easier front flex for climbing. The Genesis also adds 1 mm of lug height so is a slightly softer ground distance shoe with a more ground conforming and stable feel on more technical terrain than the Ultra.

Salomon Max Glide TR (RTR Review)

Sam: Not really promoted much and even as new now discounted, the Max Glide TR has 1 mm more stack height at the heel and 3mm more at the forefoot than the new Ultra and is 0.5 oz lighter. It has a denser conventional mesh upper, a regular tongue with no gusset and real laces, and a solid heel counter with nearly the same 3.5mm lug outsole. It has the “same” Energy Foam but due to the light weight and springier foam feel I think the foam is different, wild guess a supercritical foam? 

It has a nice rocker plus a more pronounced front flex point than the Ultra but no fiberglass plate.  Not quite as “edgy” as the new Ultra it is $80 less it is a far better value. It is my favorite Salomon shoe of 2023 for the same more moderate trails where I would take the Ultra and also for road to trail.

Salomon Ultra Glide 2 (RTR Review)

Sam: The broadest fitting Salomon ultra focused shoe with a somewhat stretchy upper the UG2 continues the more mellow than the Ultra vibe with a softer ride, easier flex for slower paces but with less protection (5mm lower heel, 3mm lower forefoot stack and no plate). My sample is a half size up from my normal and plush all around and I would say overly relaxed in fit compared to the Ultra at the same size up. It is my least favorite distance Salomon.

Hoka Tecton X  1 (RTR Review)

The Tecton X is more than 1 oz / 29g lighter with the same heel and forefoot platform width as the Ultra and a 10mm wider mid foot platform. The Tecton is 4mm lower at the heel and 1 mm lower at the forefoot in stack height helping at least in part explain the weight difference.

Tecton has a dual density midsole with a layer of supercritical foam and dual parallel carbon plates along with a Vibram MegaGrip LiteBase outsole. Compared one on each foot in an A/B run,  the Tecton X is more stable and flat on the ground (wider mid foot, stiffer plate and lower drop)  underfoot, has a more secure heel counter and a somewhat stiffer and springier (plate and foam) ride. 

The Ultra climbs at slower paces easier than the stiffer Tecton X which requires more power to really activate the plate.  Same on flats. The Ultra feels a bit deeper in cushion. My Tecton is v1 and its upper is clearly more secure with its toe box lower feeling and narrower due to its denser mesh and shape.  I was true to size (barely) in the Tecton 1 and half size up in the Ultra and its more relaxed lighter on the foot mesh and fit is clearly felt. For speed Tecton X, for distance comfort Ultra

Nike Ultrafly Trail (RTR Review)

Slightly lighter at 10 oz  / 284g (US9) with a bigger 38.5 mm heel / 30 mm forefoot stack height, Nike’s first entry in the plated ultra trail shoe race with the famous Zoom X foam and is the first Nike with Vibram MegaGrip. At $250, it is priced up there, as is the Salomon. It has a similarly light upper and one that is notably broad up front. My sample at TTS could actually be sized down. Both have very comfortable uppers with the Ultra’s more secure except at the heel where the Nike with a real heel counter is superior. Ultrafly has a completely rigid carbon plated shoe but doesn’t feel like it that much until things get more technical and on steep uphills. 

The Ultra with its more flexible fiberglass plate adapts to rougher terrain better and its forefoot is more friendly in its protection while the Nike pulls ahead on smoother, faster terrain. For fast smoother terrain and door to trail the Nike pulls ahead. For long runs at moderate paces on trail terrain the Ultra .      

New Balance FuelCell SC Trail (RTR Review)

Sam: Carbon plated, lighter at about 9.25 oz  and considerably lower stack at 31 mm heel /21 mm forefoot  and with a bigger 10mm drop, the New Balance for most will be more shorter distance oriented than the Ultra. 

Its plate has some flex but does require faster paces than the Salomon to really activate and not feel “in the way”. 

The SC Trail’s FuelCell foam is more energetic in feel if less consistent and smooth overall in the context of the feel of the entire platform with the plate in the mix. 

My sample was a half size down from my TTS and is too small for all but shorter runs. I would be true to size as I should be in the Ultra.  If your trail runs are shorter and faster, the $200 SC Trail is a joy to run. For most if you go long and want some propulsion and more protection, and at pretty much any pace, then the Ultra is a more friendly and versatile choice.

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Tester Profile

Sam is the Editor and Founder of Road Trail Run. He is 66 with a 2018 3:40 Boston qualifier. 2022 was Sam’s 50th year of running. He has a decades old 2:28 marathon PR. These days he runs halves in the just sub 1:40 range if he gets very very lucky, training 30-40 miles per week mostly at moderate paces on the roads and trails of New Hampshire and Utah be it on the run, hiking or on nordic skis. He is 5’9” tall and weighs about 164 lbs, if he is not enjoying too many fine New England IPA’s.

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'.

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70's Teen said...

How would you compare its ride to the Thundercross?

Sam Winebaum said...

@70's Teen,
Very different other than that they have the same foam. The Thundercross is more flexible has more aggressive traction and overall a shakier upper upfront. Thundercross has very decent cushion but is not as dynamic or as deeply cushioned as Ultra with no plate upfront. Thundercross for softer terrain and more casual trails, Ultra for the long. Sam, Editor

Anonymous said...

What’s the release date? Didn’t see it listed with the specs

Anonymous said...

Any quick comments compared to the Nnormal Killian shoe?

Sam Winebaum said...

Compared to NNormal Kjerag the Ultra is far far higher stacked and has the fiberglass plate. The Kjerag is way way lighter as it has supercritical foam midsole and lower stack. Both have Matryx uppers but different as the Kjerag's has more polyester and is softer and a bit thicker, I think more supportive for tech terrain. In terms of ride the Kjerega is more flexible, more agile decently protected by a more minimal woven ground filter instead of plate. Kjerag is faster more fun very versatile even road is great with a somewhat broader toe box than Ultra. Most won't ultra in it compared to..Ultra but for shorter races, everyday runs and more tech terrain where agility is key it beats the Ultra. Ultra will outdo it on long runs and if you want max cushion and a plated if flexible ride.
Sam, Editor

Anonymous said...

Thanks for the review. How does it compare to the Saucony Edge?

Anonymous said...

How does it compare in cushioning, stability and ride to TNF Enduris III ?

Sam Winebaum said...

@anonymous compared to Endorphin Edge
The Ultra is far more suitable for.. Ultra than Edge even though heavier. Its plate is more flexible being the key difference. The Edge had superior cushion feel but is far more rigid and less stable so a shoe really for fast and shorter for most.

@anoymous Enduris II
Sorry we have not tested but from recollection of v1 the Ultra is more dynamic and quicker with similar cushioning.

Anonymous said...

Got mine from Running Fanatic via eBay. Going to race the Loup Garou 100 in Louisiana’s Cajun Country in two weeks and this will be my choice. This is the ultramarathon shoe from Salomon that we’ve been waiting for. Much more comfortable underfoot than the S/Lab Ultra 3. The plate in the d’Haene is noticeably springy but not harsh, making for a better overall running experience than the Speedland GS. Will keep using the S/Lab Genesis for most of my training while adding the d’Haene Ultra for long races.

Anonymous said...

Really curious how these compare to the Hoka Mafate Speed 4. Any comments would be appreciated. Thank you in advance.

Sam Winebaum said...

Sorry I did not test the Mafate Speed 3 but by spec and purpose similar: lots of cushion and traction for long rough Ultras.
Sam, Editor

Anonymous said...

Awesome review!!!! It looks like these shoes are available now . Might try these out along with the 2 different Genesis models. These shoes were really under the radar. I have no issues paying more than 200 dollars for a max stack WELL DESIGNED tail shoe that doesn't collapse in off chamber scenarios, feels fast, has a flex--able fore foot for climbing, and runs nicely during flat boring sections of trail. Mafate Speed 4 and GS-PGH get close, but both a bit clunky for different reasons. Your guys" reviews and comps are super awesome.... Gus

Sam Winebaum said...

Thanks for the kind shoutout ! Our Genesis review is here. Also a fine option and at $150 a very solid value but not quite the tank the Ultra is.
Sam, Editor

Tim Finocchio said...

Hi - how come the Salomon website lists a different stack heights of 20m and 28mm vs what you have quoted? Is the Salomon website wrong?