Salomon Sonic Pro – Review – a stiffer, “Sense”ified X-Series

For 2016 Salomon is replacing the excellent S Lab X-Series shoe (reviewed here, here, here, and here) with a model called the Sonic in numerous versions- an S Lab version, a Sonic Pro version, and a Sonic Aero version. Salomon worked with Max King in 2015 to “improve” the X-Series hybrid road/trail shoe. It was mentioned that the major changes were in the upper mesh, the lacing system for the S Lab version (which uses a retro “standard” lace system), and the details of the TPU overlays on the upper. Well… there are more changes than just these. This review is of the Sonic Pro and will be followed by a review of the S Lab Sonic soon.

First let’s remind ourselves of how good the X-Series shoe was- it was received with uniformly excellent reviews from many reviewers from many different use perspectives. I particularly liked how the shoe performed on typical Western mountain trails in the US with surprising stability in even very rocky and rough conditions. With the exception of extended scree traverses, this shoe was a very versatile mountain trail running shoe coming in at flyweight numbers (218 gms for US 7.5, 40 2/3 (EU)). It remains my primary trail running shoe.

Now let’s talk about the difficult task of “improving” any good or great shoe. In my opinion this can only happen with very minor, evolutionary changes with the realization that the designers may not have a full grasp on why the shoe was so great to begin with. This can be analogized with fooling around with a many-term, non-linear, mathematical equation whilst not knowing what the term functionalities are and expecting to have predictive results- not likely! Such is perhaps the case here, but I will hold final judgement until I have fully investigated the S Lab Sonic. However, based on an initial 35 miles (50 km) in the Sonic Pro, things do not look very good. This is an initial impressions review however, and I will follow up with updates.

Sonic Pro

As mentioned above, the Sonic Pro is a 2016 derivative of the X-Series and carries a similar appearance and outsole. It is the heavier version of the S Lab Sonic, but is otherwise pretty much the same as the S Lab (I will have more on the S Lab version in a separate post). My US 7.5’s (40 2/3 EU) weigh in at 234 gms (8.3 oz) which is about 20 gms (8%) heavier than the 2015 S Lab X-Series. This is expected given that this is a “lesser” model in the Sonic line at a lower price point. The weight of the S lab version is on par with the 2015 X-Series.


The colorways include the black with orange shown here (Salomon calls it “tomato red” but it is definitely orange), a monochrome bright blue, a monochrome bright yellow-green, and a tomato red with black (the reverse of the shoe above) for men. For women there is a purple with bright yellow-green, a monochrome teal blue, and a monochrome pink. Salomon appears to be reserving the monochrome red colorway for the S Lab version.


The construction of the Sonic pro is essentially the same as the X-Series with the same midsole, cushioning, drop, and perimeter structure. The Sonic Pro (and S lab Sonic) shoe and the X-Series are basically road versions 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 Sonic Pro along with a much cushier midsole but with a less aggressive outsole.


The upper is constructed of similar materials and design that was used in the X-Series. The lycra front portion of the upper has been replaced with a new mesh material that looks like a cross between the X-Series lycra with the mesh of the Sense line.

Th interior of the shoe incorporates the Endofit construction as in the S Lab X-Series and Sense lines of trail running shoes. This fit 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. The TPU overlay reinforcements, called “Sensifit” by Salomon, take the familiar zig-zag shape, as usual, but also wrap around the toe area for some minimal protection.

Importantly, the upper shape has been changed- it now resembles much more of a Sense profile than the X-Series profile. The differences are primarily at the front of the ankle where the upper has been shaved down to look much more like the Sense topology. In fact the entire front profile is much more “flattened” when compared to the X-Series and can be described as a Sense-like upper grafted onto an X-Series chassis. This does affect fit and run feel as will be described later.

Slide2 (1)

Proflies of the Salomon Sonic Pro (top), Salomon S Lab Sense 4 (middle), and the Salomon S Lab X-Series (bottom) showing the Sonic Pro to be a a Sense-like upper grafted onto the X-Series chassis.

The side mesh panels on the outer side, the beefy nylon mesh rear portion of the upper, and the beefy nylon mesh inner side all remain essentially unchanged from the X-Series. As with the X-series, the design includes no toe protection other than a small front bumper. If you are a frequent “toe-stubber” then you may have some issues with this design.


View of the Salomon Sonic Pro from above showing the new mesh material on the front section.


A close-up of the new mesh material that seems to be a hybrid of the original X-Series lycra and the mesh used in the Sense line.

The ankle cup is still symmetric as was the case in the X-Series and the rear upper construction is unchanged.


The ankle cup of the Sonic Pro is symmetric as it was with the X-Series.


The heel and heel counter remain unchanged from the X-Series design.


As with the X-Series, the Sonic pro is a highly cushioned shoe, at least in the Salomon universe. On Salomon’s 1-5 scale of “cushion” in their technical literature, the Sense 5 Ultra ranks at “2” whereas the X-Series is rated “4” where a larger number indicates more cushioning. This difference can be seen in the reported midsole thicknesses where the Sonic Pro has a 24 mm heel and 16 mm forefoot EVA stack whilst the Sense 5 Ultra has 18 mm heel and 14 mm forefoot stack. So 6 mm more EVA at the heel and 2 mm more in the forefoot. Both models use the cushier “triple density” EVA “EnergyCell+” construction (where a cushier EVA is strategically placed in a matrix of a less cushy formulation).

The Sonic Pro 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 is nearly exactly the same as the X-Series right down to the widths and the specific grip patterns. This is acceptable given the great performance that this outsole exhibited on the X-Series. The only notable difference is in the rubber composition in the medial toe-to-midfoot area where a carbon rubber is used in the Sonic Pro. Such carbon-particulate rubber compositions are tougher and more durable than non-particulate reinforced rubbers so this may lead to better wear for some users. However, even after over 1000 km my X-Series showed very little wear in this area. But if you “scuff” your toe you may see better wear.

This same carbon rubber insert on the medial toe of the outsole was seen last year in prototypes that Salomon athletes were wearing in mountain ultras (e.g. Kilian Jornet and Anna Frost at Hardrock) so there may be a wet or dry grip advantage with the composition and placement. I have not had these shoes in any truly wet or muddy or technical rock conditions yet so I cannot make any evaluation at this point. I will note that the S Lab Sonic does not have the carbon rubber in this area- it is exactly the same as the 2015 X-Series.


Comparison of the outsoles of the Salomon Sonic Pro (top) and the Salomon S lab X-Series (bottom). The outsoles are the same with the exception of the use of carbon rubber in the medial toe area on the Sonic Pro.

Initial Running Impressions

I have had the Sonic Pro out for about 35 miles (about 50 km) on dry pavement, packed snow trails, some ice, and a bit of mud.

The Sonic Pro is so much like the X-Series that I expected it to run in very similar way. In some aspects it is the same- the same platform, the same cushion, and the same excellent mid-foot support. However the shoe is significantly stiffer than the X-Series and I have found this stiffness to seriously detract from the comfort of the shoe. It also detracts from the excellent proprioception that the X-Series exhibited. Perhaps the shoe will become less stiff with use but I am not sure what the purpose of stiffening the shoe is. With more miles this may become apparent, but I remain skeptical.

I have also noted a different, lower, level of support around the ankle as would be expected by the “Sensification” of the upper topology. This lower level of support has been felt in off-camber and other stability-challenging situations and for me detracts from the utility of the shoe. I expect that the Sonic Pro will not be as good a performer on trails and in the mountains as the X-Series was (is).

Other than the increased stiffness the shoe has performed similarly to the X-Series and, to first order, it represents a direct replacement albeit with a bit of a different ride, but still a nice ride. The cushion is nicely balanced and “natural” feeling and the grip on the road, packed snow, and mud is, as expected, the same as with the X-Series.

More miles will tell so stay tuned.


$140 US. Expensive but a bit lower than the 2015 S Lab X-Series, although the higher weight should account for the differential.

Bottom Line

A stiffer X-Series with a modified upper topology. Be sure to try these on first if you are an X-Series fan as they do feel different, and, for me, negatively so.



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