Salomon S Lab X-Series – Review – a nice addition to the S Lab group

I recently received a pair of Salomon S Lab X-Series a “new for 2015” road shoe. As far back as I can remember, Salomon have never offered a road running shoe. And if they have offered a road shoe in the past, they certainly have not considered such shoes as a core part of the brand. So it was with a bit of apprehension that I slipped on the Salomon S Lab X-Series for some mixed miles of road and buffed trail. This apprehension soon evaporated into the unseasonably warm air here in the central Idaho mountains and was replaced by pure confidence in Salomon’s ability to enter the road shoe market.

Note: 3 April 2015- I have posted about a direct comparison of the X-series and the Sense 4 including a couple 100 miles (300 km) on each model both on trail and off-trail in a variety of conditions here.

Note: 23 April 2015-  I have posted an update on the performance of the S Lab X-Series at about 700 km (435 miles) of use here.

Note 30 May 2015- I have posted a final update on the S Lab X-Series at about 1200 km (750 miles) here.

Salomon X series overall

The Salomon S Lab X-Series- a road shoe from the trail experts.

The S Lab X-Series shoe is basically a road version of the Sense trail running shoe. What this means is that all of the fit technologies that make the Sense such a great trail shoe have been incorporated into the X-series along with a much cushier midsole and less aggressive outsole. The end result is outstanding.


The upper is constructed of materials and design that is expected for a road shoe that will not see much, if any, technical trail conditions. As such, the front portion of the upper is made of lycra with some side mesh panels on the outer side for ventilation. The rear portion of the upper and the inner side is made from a much beefier nylon as expected and needed for proper heel structure and protection from opposite shoe heel scuffing. The design includes no toe protection other than a small front bumper- you do not want to stub your toe on a rock in these shoes.

Salomon X Series side veiw


Th interior of the shoe incorporates the Endofit construction as is utilized in the S Lab Sense line of trail running shoes. This feature has received uniform rave reviews and general acceptance as a superior design element in current running shoes. The Endofit approach produces a secure yet very comfortable fit via an inner “sock”. This fit is often described as “slipper-like” and I concur.

Another feature to note is that the ankle cup topology is symmetric, meaning that the curved cup is the same on both the inner and outer sides. This is not the case for the Sense where the inner cup is taller than the outer cup as will be shown below.

Salomon x series ankle cup

Symmetric ankle cup in the Salomon S Lab X-Series.

The polymer overlay reinforcements take the familiar zig-zag shape but also wrap around the toe area for some minimal protection. The toe box is substantially wider than that in the Sense trail shoe line as will also be shown later.

Salomon X series viewed from above

View from above of the Salomon S Lab X-Series showing a toebox and forefoot that is wider than that in the Sense 4 Ultra.


Perhaps one of the most differentiated features of this shoe to the Sense line is the EVA cushioning. On Salomon’s 1-5 scale of “cushion” in their technical literature, the Sense 4 Ultra ranks at “1” whereas the X-Series is rated “5” where a larger number indicates more cushioning. This difference can be seen in the reported midsole thicknesses where the X-Series has a 19 mm heel and 11 mm forefoot EVA thickness whilst the Sense 4 Ultra has 13 mm heel and 9 mm forefoot thicknesses. So 6 mm more EVA at the heel and 2 mm more in the forefoot. Both models use the cushier “dual density” EVA construction (where a cushier EVA is strategically placed in a matrix of a less cushy formulation).

The X-Series also uses the ProFeel film technology developed for the Sense series shoes so there is good protection from rocks if one uses this shoe on trails.


The outsole of the X-Series is a hybrid trail/road configuration that combines some deep lugs asymmetrically with smoother areas of a design similar to other lightweight road shoes. Salomon claims that this design allows for both good grip on flat paved surfaces (wet or dry) as well as non-technical trails. There is also a deep cutout extending from the midsole into the heel region, which is likely a weight saving feature but may also provide additional longitudinal rigidity.

Salomon X series outsole

Outsole of the Salomon S Lab X-Series showing asymmetric tread pattern and deep lugs toward the outer portion of the forefoot. The wear layer is glued in numerous pieces to the EVA midsole, something which has proven to be problematic in the past- time will tell.

The outsole utilizes Salomon’s proprietary “Contragrip” polymer compound that has been in use on many Salomon models over the past few years. The wear layer is glued to the EVA midsole in segments much like the original Sense model of 2012. This gluing proved troublesome as the individual segments had a tendency to peel off and thereby limited the life of an otherwise sound shoe. Salomon seemed to fix this problem in the Sense 2 but went to a single molded piece in the Sense 3 (and 4). The single piece construction limits the linear area of exposed glue lines and seems to be a better choice for durability. Perhaps Salomon have figured out how to reliably use the segmented design but I will be casting a wary eye as I put miles on the X-Series.

Salomon S lab Sense 4 outsole

Salomon S lab Sense 4 Ultra outsole showing the single piece wear layer construction.

Running Geometry

The overall construction of the shoe has a significant “rocker” geometry similar to that found on many other trail and road shoes, and particularly on the Hoka line. The rocker geometry is said to better enable a forefoot strike when combined with a low drop. Many have noted favorably how well this has been executed on some of the Hoka models.

Salomon X seies side view

Side view of the Salomon S Lab X-Series showing the significant “rocker” element in the forefoot.

The drop of the X-Series is quoted as 8 mm with total stck heights of 23 mm heel and 15 mm forefoot. This drop is something of a hybrid between a “traditional” high heeled road shoe and a low drop trail shoe. I would prefer a lower drop but will defer judgement until I accumulate a significant volume of miles on the shoe.


The S Lab X-Series shoe is quoted as weighing in at 218 gms (7.7 oz) for a size 9 (US). My size 7.5 (US) (40 2/3 (EU)) tipped the scales at 215 gms (a little less than 7.6 oz). That is lighter than the quoted 238 gm for a size 9 (US) in the Sense 4 and the actual measurement of my Sense 4 Ultras in size 7.5 (US) at 227 gms, so a light shoe indeed. This is a good thing as weight matters- a lot, particularly for lighter weight (sub 125 lbs) runners like me.

Comparisons with S Lab Sense 4 Ultra

Since many of those who currently use the S Lab Sense shoe are likely to consider this shoe for road (and buffed trail) use, a comparison of the significant differences with the current Sense 4 Ultra model are presented below. The first comparison shows the larger toebox and forefoot area.

Salomon X series comparison forefoot

Comparison of the forefoot area of the Salomon S Lab Sense 4 Ultra (left) and the Salomon S Lab X-Series (right). Both the toebox and the forefoot width are larger.

A second comparison shows the substantial “rocker” geometry compared to the Sense 4 Ultra.

Salomon X series compared to Sense 4

Salomon S Lab X-Series (upper) and Salomon S Lab Sense 4 Ultra (lower) showing the substantial “rocker” geometry incorporated in the X-Series when compared to the Sense 4 Ultra.

A third comparison shows how similar the heel cup support structure is on both shoes.

Salomon S Lab X-series back comparison

Rear view of the Salomon S Lab Sense 4 Ultra (left) and the Salomon S Lab X-Series (right) showing similar heel support structure but very different ankle cup configurations.

However the ankle cup area is quite different with the X-Series having an symmetric cutout design whereas the Sense 4 Ultra has an asymmetric design and more rear roll-over in the padding.

Salomon X Series ankle cup comparison

Ankle cup comparison showing Salomon S lab Sense 4 Ultra (top) and Salomon S Lab X-Series bottom. The Sense 4 has an asymmetrical cup whereas the X-Series is symmetric. The Sense 4 also has much more rear roll-over of the padding.

Initial Running Impressions

I have had the X-Series shoe out for about 50 km of mixed use- about 30 km of road and 20 km of buffed trails. If you are a S Lab Sense user, you will note that the fit is very much like the very comfortable “slipper”-like feel of the Sense 3 and 4. The X-series is comfortable from the outset and I have noted no change in these first 50 kms. Also, if you are a Sense user you will immediately notice the “rocker” geometry and the way the shoe subtly prods your posture forward and on to the forefoot. I found this to be a nice feature of the Hoka Stinson trail shoe particularly given the maximal cushioning of that shoe. With the highly cushioned shoes there is the reality that when the cushion is deformed and your foot forms deep into this deformation one must overcome the not insignificant physical barrier thus created. The “rocker” geometry does a good job of dealing with this. And so it is also with the X-Series which has a much more padded midsole when compared to the Sense 4 Ultra.

Continuing with this, the second thing one will notice is the substantially greater cushion when compared to the Sense 3 and 4. On road surfaces this added cushioning is very apparent and quite welcome. It almost makes one want to actually consider running on roads from time to time (heresy!). On the trail the difference is not really noticeable although I have not taken the shoes on any technical and rocky stretches yet. Stay tuned.

I really like the feel of these shoes while running. The combination of fit, cushioning, geometry, traction, and weight seem to provide a near optimum balance between comfort and efficiency on roads. As far as trails, I will be giving these shoes a full workout once the snow recedes in the next few weeks. Based on these initial impressions, I think that this shoe will be a nice option to have available in ultra races where there is a lot of dirt road and/or buffed trail. I am likely to put these into a drop bag at an aid station in a 100 km race this year where the last 13 miles are a downhill charge into town on graded dirt roads. The cushioning and rocker geometry will be just the ticket!


$160 US. Steep but if these shoes last as long as the other S Lab shoes I have used then the “cents per mile metric” will be more than palatable. Only time will tell.

Bottom Line

A very nice entry by Salomon into the road shoe arena with all expectations that this shoe will be an outstanding performer- stay tuned.

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:



16 thoughts on “Salomon S Lab X-Series – Review – a nice addition to the S Lab group

  1. Now, Salomon just needs to discover that there are colors beyond red, black and white.

    I know, shallow comment, I would wear any color if the fit, performance and reliability were right, but still…

    • Hi Laurent,

      Yes, the limited color palette could be considered “boring” but I sort of like the timelessness of the systematic use of a racing color, much like is done in automobile racing where each country has an assigned racing color.

      For more excitement Salomon really juices it up with the other lines… SpeedCross comes to mind!

    • Thanks Jeff, I am looking forward to putting some miles on them as I think they are going to be more functional on trails than might be readily apparent.

  2. Thank you for a fantastic review. I have been anxiously awaiting such a comparison to the Sense Ultra. I may have missed it, but would you say that the sizing is the same? I wear an 11.5 in the Sense Ultra 3, and they are my best fitting shoes- do you think I can order an 11.5 in these? Thank you again!

    • Hi Sean,

      Thanks and I am glad that you found the review useful.

      As far as sizing, I feel no difference in the fit between the Sense 3 Ultra, the Sense 4 Ultra, and the X-Series with the exception of the slightly wider forefoot and toe box on the X-series. I should think that this should hold at your size as well, but you would do well to order a couple of sizes from Running Warehouse and try them on. Running Warehouse offers free 2-day shipping and free return shipping so other than the 2-day wait it is just like going to a local running shoe shop- except that Running Warehouse have a very large inventory and you will not have to put up with a poorly trained salesperson babbling shoe-speak gibberish.

      • Thank you Robert! I am a big RW fan, and will certainly order through them. (I seriously doubt I’d find these in any stores near me anyway!) I’ve honestly never loved a shoe quite like the Sense 3 Ultra, and every time I wear them have wished for a road model for those necessary- but unfortunate- road days. These really sound like a winner. Will have to hope that Salomon eventually releases a lower drop version closer to the Sense Ultra line up, but I will probably appreciate the extra cushion on the pavement.

  3. Would you say the drop feels like a true 8mm? I have talked to a few people and they say it feels like less then that, perhaps from the slight rocket?

    More importantly how does the drop feel compared to the Sense Ultra? Does it feel like double as the numbers would suggest?

    • Hi Rory,

      What I can say about the feel of the drop is that I noticed no substantial difference from the Sense 4 (or any other Sense). I found this to be curious given that the X-Series drop is doubled from the Sense, but as you mention, the “rocker” is likely playing some role with this. A higher drop with a different design (like the SpeedCross) is very noticeable to me.

      So I would offer that you are not likely to feel much of a difference from the Sense, but you should try them on and do a few strides to make sure. I do this with shoes from Running Warehouse by taping the outsole with blue painters tape and doing some limited striding on pavement, grass, and smooth trails. If the “feel” is not right I just take the tape off and send the shoes back since there will be no marks on the outsole. Just a suggestion.

    • Hi Drew,

      No, I do not have flat feet so I cannot help with recon on the X-Series. Not sure what might be the best approach for someone with flat feet. Good luck finding something that works for you.

  4. Do you wear the same size with both the sense and the x-series or would you recommend to seize down with the x-series version?

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