Salomon S Lab Ultra at 1000 km – a great shoe gets better

About a year ago Salomon began showing the Spring 2018 product line-up for trail running. They decided (for reasons not obvious) to replace the outstanding and very popular 2017 S Lab Sense Ultra entirely- i.e. no update to the current model, no Sense Ultra 2, just drop the model (the Sense Ultra was still in the SS18 catalog but availability was clearly limited to the in-stock production from 2017). Given that this shoe was the best selling S Lab shoe ever, many did not understand the logic behind the decision. I too questioned this decision and,  based on my substantial experience with the Sense Ultra, purchased additional pairs for the upcoming 2018 running season.

The 2018 replacement for the S Lab Sense Ultra model is the S Lab Ultra (this shoe appears in the Salomon SS18 catalog as the S Lab Sense Ultra 2, a name that was dropped by by Salomon by Spring 2018 and replaced with the simpler “S Lab Ultra”). The S Lab Ultra is a very different shoe with a narrower last, a new upper with much more protection, a new midsole construction, and, most prominently, external (not laminated) Sensifit “straps” that are integrated with the footbed and the lacing. It is also about 50-75 gms heavier. Salomon worked with professional mountain trail runner and 100+ mile race specialist Francois D’Haene on the design and they focussed on performance optimization for the UTMB (Ultra Trail Du Mont Blanc) race terrain. The shoe is rumored to be based on D’Haene’s actual foot shape that is very narrow and long.

I did not do an initial impressions review of the S Lab Ultra because I was rotating it through with a couple of pairs of Sense Ultras and did not feel that I was giving it enough testing time. Now that I have about 1000 kms on the S Lab Ultra I feel confident in what I have experienced.

All of the additional “stuff” on this shoe comes at the cost of increased weight- 285 gms for my size 7.5US/40 2/3 EU. This is to be compared with the Sense Ultra which weighs in at 260 gms. This is a small but not insignificant difference particularly for long runs/races.

Salomon S Lab Ultra 2018. A new shoe in virtually all respects when compared to the S Lab Sense Ultra of 2017, including new external sensifit straps.

A critical eye will immediately question the need for the external SensiFit “straps” in a running shoe. Given that there were no significant issues with upper stability and foothold in the Sense Ultra on challenging mountain terrain, this feature seemed to be either “gimmicky” or actually added some level of performance. Only individual testing would suffice to answer this question. One can also immediately see the heritage of the external straps in current and past Salomon S Lab Skate boots for cross country skiing. The latest (super light) iteration includes a monocoque carbon fiber shell for the lower part of the upper, a carbon fiber cuff, and an integrated strap (all for the measly sum of $1,200 US!).

Salomon S Lab Carbon Skate Boot (left) and S Lab Ultra (right) showing the cross country skiing heritage for external straps on footwear, where such straps have been included in Salomon’s top line models for over a decade.

But cross country skiing, and skate skiing in particular, is a very different situation as it comes to footwear. The fundamental skating motion involves powerful lateral strides where a stiff sole and upper are critical for efficient force production against the snow and the integrated straps assist in further immobilizing the foot to ensure no lateral movement within the boot. This scenario is not something that plays any important role in mountain trail running so it was an open question as to why Salomon put these straps onto their flagship mountain ultratrail running shoe. Well, it turns out that there are reasons and I will get to that below.

I am still looking to see if Salomon will ever use their substantial knowledge of the use of carbon fiber reinforced technology in their running shoes. It seems to be a natural progression for certain areas (like the stiff carbon fiber plate under the foot in Nike’s Zoom Vapor Fly 4%) but nothing yet from Salomon.


The upper is very different from the Sense Ultra with a different mesh, much beefier toe bumper, substantial polymer overlay protection, and, of course the SensiFit “straps”. Salomon also returned to a “top loading” lace garage seen on Salomon shoes in the early part of this decade. I never had a problem when Salomon switched to a “bottom loading” configuration, but many users complained that it was difficult to get the laces into the garage due to the interference with the tightened laces. There is a simple technique that avoids this issue but some never mastered it. Now it seems that Salomon might go back to the original “top loading” approach.

Salomon S Lab Ultra uppers after 1000 kms. Notice, when compared with the Sense Ultra of 2017, the beefed-up toe bumper, substantial polymer overlay protection, and SensiFit “straps”. I expected the shoe would run warmer but it hasn’t.

Given all of the “beefing-up” of the upper I expected that the shoe would run warmer than the Sense Ultra but this did not happen. Apparently there is still sufficient ventilation, even with all of the overlays, to keep my feet as cool as they are in the Sense Ultra.

I was initially concerned about the interface between the mesh portion of the upper and the polymer overlay protection. Such interfaces typically yield the highest localized strain and can often lead to increased erosion and wear. However, even after 1000 km (600 miles) there is only the slightest evidence of erosion in these areas.

Close-up showing one of the high strain areas in the marsh-overlay area and just the very beginnings of some erosion wear along the flex axis.


The midsole is a new construction with some new materials as well. Included in the forefoot is a material that Salomon calls Energy Save that is reported to provide substantial cushioning as well as dampening- similar to the “opal” inserts used on other models. In the forefoot there is an Energy Save layer under a thiner Energy Cell+ layer as can be seen from the side of the shoe- the Energy Save is the white layer and the Energy Cell+ is the red material. Other parts of the midsole (midfoot and heel) use the Enery Cell+ material exclusively which has good cushioning characteristics but less dampening. Also included in the forefoot is a ProFeel Film layer situated between the Energy Cell+ and Energy Save layers. This combination gives ample rock protection- at least for this 128 lb runner.


The outsole is essentially the same as that of the Sense Ultra with the exception that the Sense Ultra uses a black version of the Premium Wet Grip ContraGrip compound. The S Lab Ultra uses a red version. The primary difference is that the black version has carbon particles dispersed within the polymer along with the wet-grip-inducing nano-sized silica particles and nano-sized porosity. The red version has no carbon particles. Some have noticed reduced wet-grip with the red compound. I have not experienced any significant performance reduction in this regard.

Also, the outsole does not have lugs in the middle quarter (in the arch area) similar to the original S Lab Sense “Killian” shoe from 2012. There is no ProFeel Film layer in the area but I have yet to have any issue with protection.

I am getting the same outstanding level of wear performance on the outsole as was evident with the Sense Ultra. Given the current state of the outsoles at 1000 kms, I expect to get the same kind of use that I experienced with the Sense Ultra, i.e. in excess of 2000 kms of use.

Salomon S Lab Ultra outsole after 1000 kms of mountain running in a 50/50 mix of buffed single track and rocky, technical terrain. As usual the only area that shows any wear of significance is the outer right foot rear lug- a place I scrape regularly on downhill braking.

fit and performance

The fit of the S Lab Ultra is a bit on the narrow side for Salomon and Salomon shoes have always been considered narrow when compared to the chunky, high volume fit of most shoes designed in and/or marketed in the US. I was a bit concerned but found the fit to be snug and comfortable but definitely narrower. The narrowness has some advantages when in technical terrain as the shoe will fit in between rocks that I otherwise would have had to sidestep with the slightly wider Sense Ultra. I found this to be very helpful on super technical rocky downhill trails and mountainsides where I was able to keep a rhythm that otherwise would have been necessarily syncopated and therefore slower. Nice!

I have never noticed the increased weight over the Sense Ultra in runs as long as 5 hours however one might begin to tire earlier in longer runs/races.

After these first 1000 kms, I find the fit continues to be comfortable and have had no issues with hot spots or pinching. The shoe does feel very different than the Sense Ultra however. Specifically the S Lab Ultra is stiffer and the exteroception* is reduced. Although this is generally not considered a good thing, there are trade-offs occurring that, depending on terrain, can lead to advantages. The cushioning is just slightly less than the Sense Ultra but it has not affected my comfort level even in longer runs

One of these trade-offs is stability on sharp rock. The Sense Ultra, although very good does not hold a candle to the S Lab Ultra when traversing a sharp rock field at speed. The stiffer, less compliant S Lab Ultra provides, under similar conditions, a significant increase in placement stability and a much reduced lateral displacement at the footbed. This is where the “straps” come in. One can feel the straps lock your foot in when you hit high-level technical terrain (e.g. loose, sharp rock on steep slopes).

I tested the S Lab Ultra against the Sense Ultra on multiple back-to-back intervals on a steep (25-35% grade) 300 m climb followed by a return run down. Both my sense of stability and “sure-footedness” were superior in the S Lab Ultra and my times were about 5% faster at the same exertion level (HR and RPE). 5% is a big number here and it may be much smaller on less demanding terrain but I’ll take that improvement particularly on long steep climbs and descents!


$180 US and well worth it. With the miles that this shoe is giving along with the comfort and performance it is a hard to beat value.

bottom line

A great replacement for the Sense Ultra with enhanced rocky terrain stability that comes at a slight cost in weight.

*many manufacturers and reviewers of trail running shoes (including me in the past) often utilize the term proprioception to describe how well a shoe allows one to “feel” the trail. However, proprioception is actually defined as: the perception of joint and body movements as well as position of the body, or body segments, in space. Whereas exteroception is the sense of the outside world’s interaction with our body mainly through touch. Exteroception is an input to the determination of proprioception. Proprioception is a much bigger thing and studies have found that it can be learned to some extent but also has a genetic component as well. As it concerns shoes, one should use the term exteroception since this is the information one is getting from the shoes to allow the brain to then compute a proprioceptic understanding of the instantaneous position of the body in space. It’s the difference between “trail feel through the feet” (exteroception) and “total body position feel” (proprioception).

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