Salomon S Lab X-Series Update – a continuing great performer

I have reviewed the Salomon S Lab X-Series “road” shoe previously with initial impressions here and, after some use on varied terrain, in comparison to the S Lab Sense 4 Ultra trail shoe here. Initial and continued use of the S Lab X-series “road” shoe revealed that it not only performs very well on roads but also on the trails, at least on the trails here in the Northern Rocky Mountains of the US.  This post is an update after considerable additional use of the X-Series on a wide variety of terrain.

I now have about 700 km (435 miles) on a first pair of X-Series and have recently introduced a second pair of X-Series in rotation. A third pair is being set aside for races. As should be obvious, I have committed entirely to the use of the X-Series for all trail and ultra-trail races and associated training going forward in 2015. When compared to the Sense 4 Ultra, the X-Series has sufficient trail prowess to be a good choice for all but the most demanding of technical trails (think Trofeo as an example of where you might choose the Sense 4 over the X-Series). At the same time the X-Series offers significantly increased comfort over the Sense 4, particularly on long (>30 km) runs. The following is a summary of my experience using the X-Series “road” shoe on trails.


As expected from a “road”- trail hybrid shoe, performance on flatter and buffed trails is outstanding. But, as has been indicated in previous reviews, the X-Series exhibits surprising performance on trails in general and specifically on rocky and “technical” sections, both on the ups and the downs. Based on the Salomon literature and introduction material, the X-Series was not designed as an all-around trail shoe, yet my experience is that it is and it is a great performer.

The X-Series has continued to shine on anything that the Rockies can dole out with the exception of deep mud where the larger platform and ground contact area of the X-Series lead to a fair bit of “float” when compared to the Sense 4 and FellCross 3*. I have been able to run with confidence on all of the trails that I have run in the Sense line in the past 3 years and notice very little if any difference in performance. What is different is comfort, where the X-Series is much superior, at least on my 60 year old feet. It is not clear why the X-Series is so comfortable on longer runs, although I suspect that the midsole design in the midfoot is playing a large role. Overall from a performance perspective, I can highly recommend the X-Series as an outstanding trail performer and as a shoe quite ideally suited to ultra trail events.


As noted previously, the X-Series utilizes some materials that have not been seen on Salomon shoes in the past- specifically the Lycra forefoot upper and the super-thin mesh on the outside mid-foot upper. In addition the outsole wear layer is glued onto the midsole material in segments which is a design approach that Salomon have had issues with in the past. These are the areas of the shoe that I have been keeping an eye on.

As of this juncture and with about 700 km (435 miles) of use, it is apparent that these “suspect” areas and the shoe in general is holding up exceedingly well. There is no evidence of excessive wear on any section as can be clearly seen in the following images.



Salomon S Lab X-Series after approximately 700 km (435 miles) of use. No evidence of excessive wear anywhere on the upper, the outsole, or in the construction.

A closer look at the outsole shows that the wear layer is quite durable, more so than what I have experienced with the Sense line of shoes over the past three years. As a supinator I typically see increased wear on the outside of the mid-forefoot and on the outside of the heel area. As can be seen in the image below neither of these areas show an increased wear relative to the rest of the outsole. I am not certain as to why this might be but the increased footprint and increased area of contact may be playing a role. The geometry of the shoe design (including increases in footprint, area of contact, the “rocker” element, and the details of the midsole structure and composition) is likely the reason for such even wear of the outsole.


Outsole of the X-Series after 700 km (435 miles) of trail running including about 30% rocky technical, 60% buffed singletrack, and 10% road use.


I have experienced no significant issues with use of the shoes- the fit has remained excellent, the stability and traction have not diminished, and the materials are holding up well. I have, however had one incident that is making me focus a bit more on the applicability of this shoe in truly technical terrain.

Although this incident could have been entirely stochastic, I have never had such a thing occur in over 35 years of running. While on a long run through some very technical terrain I noticed that there seemed to be a small stone in the shoe. After a while I stopped and took the shoe off and emptied out any debris that had collected inside the shoe. Some small stone chards fell out. I put the shoe back on and continued running however the stone I felt previously seemed to still be in there. So I stopped again and emptied the shoe, something else fell out and I thought that would be it. But after continuing I still felt the stone. So I took the shoe off again and felt very carefully and realized that there was a stone under the insole, something that has never happened to me. I removed the insole and finally found the culprit- it was a small sharp stone that had penetrated through the exposed midsole (EVA) material, through the ProFeel rock plate, and into the interior of the shoe. The following images show this.


Looking into the shoe with the insole removed showing the puncture from a sharp stone.


Image of the outsole, the sharp stone, and the place where the sharp stone penetrated the outsole area (I saved the stone after removing it).


The insole removed where the penetration can be seen in the lower section of the trailing end of the forefoot.


The opposite side of the insole showing the penetration point.


The penetration point on the underside of the insole and the offending sharp stone.

It took quite an effort to remove the sharp stone from the shoe. I was never able to get it back in either. I expect that this was likely a chance event- the right sharp stone in the right orientation, the right location on the sole, and the right placement of the shoe on the stone. But I will be keeping a peeled eye towards any further events- both with or without puncture. It still seems unusual that such a stone would penetrate the ProFeel film, but that seems to have clearly happened.

Bottom Line

The Salomon S Lab X-Series hybrid “road”/trail shoe is an outstanding trail shoe that is very light, has excellent fit, durable upper and outsole, and is exceedingly comfortable on long (>30km) runs. The shoe handles anything from buffed singletrack to highly technical rocky terrain to wet rocks/roots and medium mud. Deep mud conditions will be challenging in this shoe (as they are in the Sense 4 Ultra) so if deep mud is common in your running there are better options.

I can highly recommend this shoe for both training and racing trail and ultra-trail events.

Note 12 July 2015

It seems that Kilian used the S Lab X-Series for some portion(s) of his 2015 record-breaking performance. Here he is changing shoes at Telluride aid station before climbing 1400 m (4500 feet) up Bear Creek on road, then trail, then snow fields over Oscar’s Pass and then a 950 m (3100 foot) decent into Chapman. Looks like he is changing into the X-Series (with an all black wear layer) from the 2016 Sense (or some new prototype). This is a testament to the versatility of the X-Series, a supposedly “hybrid” road/trail shoe!

Kilian Hardrock w_2016 shoes

Kilian changing shoes at the 2015 Hardrock 100 Telluride aid station before a difficult 1400 m (4500 foot) climb and 950 m (3100 foot) decent. Looks like he is changing into the 2016 X-Series from the 2016 Sense. Photo credit:


*Generally, US trails do not include wet grass conditions as most trails are developed, are substantially dirt and rock, and it is not encouraged to deviate from the established trail. Fell running on the other hand is very much the opposite. I have not tested the X-Series in “Fell” conditions so all comments here exclude application to Fell running.



11 thoughts on “Salomon S Lab X-Series Update – a continuing great performer

  1. I had a few runs in these as well. The first run was on pavement, below freezing. I found the shoe to be rather rigid. I told myself “these are going to need some breaking in”.
    Rather, I think it was material physics coming to haunt Salomon. Certain materials behave a certain way at “normal” temperature, but quite differently below freezing.
    In this instance, the outsole and the fabric above the forefoot were quite stiff, with the fabric above the forefoot creasing in a manner that applied pressure downward towards my toes.
    The shoe also had a very peculiar (“loud”) sound signature on pavement.

    My other runs were on non-technical trails and there the shoe really shone. These runs were in much warmer weather and the materials appeared a lot softer. The fabric above the forefoot, in particular, softened rapidly as my feet started releasing heat, so there was no discomfort whatsoever resulting from creasing or otherwise.
    On those trails, I thought the shoe performed even better than the Sense Ultra, but I noted, as you did, that the rock plate is a lot thinner, obviously. I did not have that extreme piercing incident you experienced, but I distinctly felt some rocks at times.

    What’s my conclusion? Too early to tell.
    But, at this time, I am not sure the X-Series reaches its official goal of doing for pavement what the Sense has done for trails.
    I will have to see how they perform after more of a break-in period.

    • Hi Laurent,

      I have not noticed the “stiffness” of the materials at low temps. I have had these shoes out in weather in the 20’s F and still found them to be flexible, but perhaps you were out in colder conditions. I did see that Salomon uses a 60C EVA for the higher density protective layer and a 55C EVA in the forefoot area for cushioning. Neither of these compositions should be significantly stiffer at 20F but things get more non-linear below 20F.

      Running style may be playing a role in your experience- I am forefoot-strike-dominate and have not noticed any sort of “loud” planting noise. As far as the rock plate, I am not sure if it is any thinner than in the Sense at least from what literature I have been able to obtain. I did note that the ProFeel film that is used has narrow lateral cut-outs along the length of the film for flexibility. I think that the sharp stone just happened to puncture into one of the cutouts. Only time will tell as far as consistent protection, but, with over 400 miles on trail, it seems to be OK.

  2. Thank you for this update that I devoured like all your gear reviews, THANK YOU!
    I am very tempted to try those shoes but I am actually waiting for the S-Lab Wings who might be THE Salomon shoe to come (July 2015), they actually look really similar to this S-Lab X but with a trail sole.

    I just received the Mantra 3 and will try them for the next 3 months. I was looking for a trainer/long runs shoe as I can’t log my long runs in a S-Lab Sense (I wish though) since i dont feel that it provides enough cushion for me.

    • Hi Fred,

      Glad you can make use of the reviews and use updates.

      What I know about the upcoming S Lab Wings is that it will have a 9mm drop, weigh in excess of 9 oz (255 gms), and is intended to replace the S Lab XT Wings (with a slightly lower drop). Both regular and softground. More cushion than the Sense or X-Series. I think this is the updated Ryan Sandes shoe…. where the Sense is the “Kilian” shoe. “Cushion” is the new “proprioception” so I think we will see the Sense line adapt.

      I’m looking forward to what comes of the input and direction of King going forward. He has recently hinted at working with Salomon on shoes less than 6 oz (170 gms) both for trail and road. Time will tell.

      Based on what Ian Corless has put forward in his review, the Mantra 3 is a good choice for additional comfort, and at a price point.

      Best in your training!

  3. Hi Robert,

    a new pair arrived yesterday, took them for 10k on light trail. First impressions, great shoe, really glad for Your reviews and insights.
    Keep up a good work!

    • Hi Erik,

      Thanks for your comment. It is good to know that others are finding the X-Series to be a great trail running shoe. I was out in the high (10,000 feet (3000 m)) mountains here in Idaho and put the X-Series to additional tests including traversing 500 m snow fields and a long scree traverse and descent. They worked very well and I was surprised at how little debris accumulated inside the shoe. I normally have to empty out the Sense after this type of scree section but really did not have to with the X-Series. Still getting good wear as well.

  4. Can I ask whether the fit is the same, size wise, between the sense and the x-series? If I use my sense size, will that fit similarly?

    • Hi Patrick,

      For my size (US 7.5 / EU 40 2/3) the fit is the same. I should expect the same to be true for other sizes but I have no direct experience. One advantage of the X-Series for ultramarathoners is the slightly larger toe box that accommodates the inevitable foot swelling during long runs and races. Many ultramarathoners “size up” a half size for a bigger toe box but sacrifice a best fit elsewhere. With the X-Series this is not necessary so the overall fit is superior. I have not “up sized” on the Sense in the past as my feet do not swell that much, partly due to a predominant forefoot strike and partly due to a sub-19 BMI, although I think the BMI is the dominant factor in swelling.

      As I have mentioned previously, it is best to order up a range of sizes from Running Warehouse, try them on in the comfort of your own home (and away from the gibberish-spewing running shop employees), and send back the sizes that do not fit. Running Warehouse has free 2-day shipping and free return shipping so other than the 2 day wait it is no different than going to a local running shop, except that RW has a very deep inventory, particularly in small ( size US 11) sizes. If you have a good running shop nearby you are lucky but even the best shops seldom carry much stock in the high-end shoes like the Sense and X-Series.

  5. Robert,

    Thank you for the excellent reviews on the S-Lab X. Everything about this shoe looked good to me, except its “city trail” designation. I run mostly on fire roads which vary from hardpack clay, to jagged base rock, to 1″ loose and sharp gravel. I’ve been looking for a shoe that I can take out on 20+ mile training runs and races on similar roads/trails in the 50M to 100k range. I decided to pick up a pair and so far I have been very happy with them, but I’m still breaking them in.

    Prior to this I was running in Sense Mantra (original, and the 2) and just ordered the 3 because I wanted to directly compare. Initial impressions of the X gave me the impression that I was riding lower than the Mantra, even with the thicker stack and increased drop. They feel very nimble (to me, a guy who doesn’t run on racing lasts) and interestingly like you, I didn’t really notice the increased cushion until I hit the pavement.

    On the trail I get the impression that the Mantra has a thicker rock plate. Since the actual thickness of the Pro Feel Film is not given on a per model basis (is it?) one can only guess, but I do feel like I have to be a little more careful where I place my steps with the X.

    I wonder if Salomon will adapt this overall design idea into a trail shoe? It seems to be a nice middle ground to me between the high protection/high drop models and the more minimal S-Lab models.

    • Hi Jacob,

      Glad to hear that the X-Series is working out for you. I do not think that there are different thicknesses of the ProFeel film in the Salomon line. As it has been explained to me, the ProFeel film is a carbon-based fiber composite material that has very high penetration resistance but is still flexible as well. So, in the case of a sharp rock or other sharp trail feature, the film responds by transferring localized vertical displacement (strain) into a larger area strain across the film. This strain accommodation effectively, from a user perspective, makes a sharp protuberance feel much more like a rounded one. The physics are pretty straightforward. The key is the material that the film is made of. To increase flexion of the shoe the film is segmented by cutting out oblong regions that are transverse to the long length of the film (and shoe). The technology works very well as it appears to be applied through the Sense/Mantra/X-Series lines in the same way.

      It seems that Salomon will be introducing additional high performance (light) road and road/trail hybrid shoes as King has indicated that he is currently working on such, including a super light road flat. As far as trail running, the X-Series has proven (for me anyway) that the aggressive wear layers and high structure of many “trail” shoes are overkill for the application. The X-Series has also shown that the S Lab Sense is perhaps a bit too much on the minimal side as far as cushioning. We all do not have (nor do we all want) the battered, super calloused, nerve-nummed, and gnarly feet of professional mountain runners like Kilian. For long runs and races a bit more cushioning goes a long way toward performance durability for the rest of us… and, with the X-Series, without any additional weight when compared to the S Lab Sense!

  6. Pingback: Salomon S-Lab X-Series « Hike It. Like It.

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