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.
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.
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.
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.
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!
*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.