Salomon S Lab Modular Shorts System – Update

I reviewed the Salomon S Lab Modular Shorts System a couple of years ago and found the system to be very comfortable, flexible, and of high quality. After two years of use on a daily basis during the running season (April-November), I have confirmed those initial impressions and found the system to be exceedingly durable, particularly given the ultra-lightweight materials that the system is comprised of.

Salomon S Lab Modular Shorts System used by the author: boxer base layer, 4″ top layer, and integrated belt. Image taken after 2 running seasons (or approximately 4000 miles (6500 km) or 400h of use over 3-6 boxer layers and 1-2 top layers). The base layer shown has been laundered about 60-70 times.


The parts of the S Lab Modular shorts system that I use are the boxer base layer, the 4″ top (vanity) layer, and, for racing and long runs, the integrated belt. I have logged over 4000 miles or about 400 hours of mountain trail running in this shorts system and have laundered the individual elements up to about 60-70 times in a standard european-style washing machine (Bosch Axiss).

Running conditions have generally been in temperatures from about 40 F to about 85 F with generally low humidity (<50% rel., typically <20% rel.). Although I expect that the shorts system will perform similarly in more humid environments, I have no direct experience with these shorts in high humidity (>50 rel.) conditions.


Long-term experience with the system echoes my previous review:

“An “uber” comfortable, flexible, and high performance shorts system for trail running and racing.”

The comfort of this system is outstanding which means that one never actually thinks about the shorts while running. They go on, stay in place, and essentially disappear. The base layer articulations provide excellent support whilst being very lightweight and breathable. The top layer (or vanity layer) is so light and breathable that it is very much just what it is intended to be- a vanity layer. If not for social norms, one could run in just the base layer.

Boxer base layer after two running seasons of use. Still very comfortable and soft. Hem-less hems show minimal wear and a very small amount of fraying.

Close-up of the boxer base layer showing the extent of fraying on the hem-less hems- surprisingly very little.

Area on the front edge of the waist of the boxer base layer after two seasons of running showing delamination of the “sticky” silicone “stripes”. This is the only area where the “stripes” have delaminated. The delamination has not affected the performance of the shorts in any noticeable way.

After trying the 6″ variant, I have opted for the 4″ top layer with the boxer base layer. This selection is the most minimal pairing of the modular system and doesn’t try to provide anything other than functional support and a bit of protection. Initially I used the 6″ top layer and found it to be too long and then found the 4″ top layer to be too short. After extended use of the 4″variant I have now converted entirely to this length as it really does disappear and not interfere with any running activity yet provides sufficient coverage and protection.

4″ top layer after two running seasons of use. With the exception of a bit of stretch-out of the elastic waist sections, the top layer is fully intact and continues to perform to expectation.

Close-up of waist area on 4″ top layer showing absence of fraying and no delamination of the silicone “stripes”.

The other options in the system include compression support base layers (both “exo” and conventional) and longer form factors for top layer (up to 9″). These other options attempt to provide additional functionality and protection neither of which I have found to be necessary or efficacious. I suggest that one stick with the minimal system until which time that there are data that support the utility of compression wear for athletic endeavor. At this juncture the entire compression wear industry is based on hype and conjecture. See Aschwanden’s book for a full review of the efficacy of compression wear and compression technology in sports. I still do not understand the recent trend for “basketball” length shorts for running.I don’t understand them for use in basketball as well so perhaps I missing something.

The durability of this super lightweight system has been surprising given how little fabric there is. I was concerned about the durability of the hem-less hems and the grippy silicone “stripes” at the waist, thigh, and in other strategic places. Both of these features have held up well over this two year period and the only noticeable degradation is with limited delamination of some of the silicone “stripes” and a small amount of fraying at the hem-less hems. Otherwise the system is entirely intact and remains as comfortable as when new. Even after over 60 launderings, the layers are comfortable and have not lost any function and the fabrics have stayed soft to the touch.

Although I have only used the boxer base layer and the 4″ top layer, it is pointed out that since similar materials are used in the other variants in the system it is expected that similar comfort and durability will be experienced.

Modular integrated belt

I regularly use the integrated belt for longer runs and longer races and find that it provides sufficient carrying capacity for 30-50 km training runs and for supported 30-50 km races in the mountains. With the highly stretchable pockets I can load sufficient calories and water for a good 4-5 hour jaunt through the mountains at aerobic training pace. Add with some protection (light windbreaker (S Lab Light jacket), long sleeve shirt, warm beanie hat, and gloves) in case the weather turns and you are entirely sufficient. I no longer use a vest unless it is on an adventure (typically off-piste) run where additional equipment is necessary (e.g. traction devices, heavier clothing, etc.).

Salomon S Lab Modular Belt after two running season of use. Great carrying capacity, comfort, and flexibility.

Although designed to be integrated with the base layer via a series of three snap attachments at front and rear, I find that the belt is sufficiently secure that one does not have to use the snaps if this is preferred. It also means that the integrated belt can be used with other set-ups beyond the modular system.


As I explained in the initial impressions review, the S Lab Modular shorts system can appear to be expensive at first glance. But I noted then and have adhered to an approach that makes the system much less expensive than it would appear. Since the top layer is essentially just a cover-up for the base layer (it never really touches the body and rarely gets moist with sweat) it can be used numerous times prior to laundering. In addition, even if the top layer did get “crusty” it is easily rinsed out and will dry in less than 30 minutes (at least here in a low humidity western US environment). As a result of this, I will use the top layer for 3-5 runs before laundering it. Since the base layer is in direct contact with one’s body these are laundered after single use. I have six base layers but only a couple of top layers. The base boxer layer is $60 US and the top layer is similarly priced and therefore a “single” short system is $120 US (this is actually less than the pice of the prior  S Lab Sense short ($150 US) that was replaced with the modular line). Add to this that you actually get 3 shorts by buying three base layers and one top layer for a total cost of $240 US, or $80 US/”short” which is competitive with other high quality, high technology shorts currently being offered.

bottom line

A very comfortable and highly durable trail running short system that offers a wide range of options to suit individual needs.

2 thoughts on “Salomon S Lab Modular Shorts System – Update

  1. A very comprehensive review, as usual. Love it. I use the shorts and base layer on all my runs and have for the past 2 years and absolutely love them. My only complaint is with the shorts, which have quite a bit of elasticity and when they catch on the more resilient trailside brush (scrub oak) they tend to pull until the point of ripping at the split hem.

    • Hi Jamie,

      Thanks! It is an excellent shorts system- the most comfortable that I have ever used. Yes, the top layer does “float” and can catch on the vegetation. This is one reason that I switched to the 4″ variant as there is not as much “float” as in the 6″.

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