Review - Vibram Fivefingers KSO Trek

By now, almost everybody should have at least heard about Vibram Fivefingers, one of the first shoes to really bring the minimalist footwear phenom to the fore. I've reviewed and talked about "barefooting" or - more accurately - minimalist footwear on this site before, and today we're going to take a look at another model from Vibram, the KSO Trek.

The Trek, as I'm going to refer to it from here on out, differs from the previously reviewed KSO in a number of ways, despite the commonality in name. However, the KSO still stands for Keeps Stuff Out and the KSO Trek inarguably does a better job of that task than the original KSO does!
We're going to look at those differences in closer detail, but first we'll start with the few specifications that Vibram provides.

Materials:

UPPER - Kangaroo Leather

SOLE - 4mm EVA Midsole & TC-1 Rubberr

FOOTBED - Kangaroo Leather

Machine washable. Air dry away from sun or heat source.

Weight:

Men's size 43 - 6.7oz. each, 13.4oz./pair

So, an immediate difference that should be apparent is the use of kangaroo leather for the upper and footbed. This may seem an odd choice at first, but the leather that Vibram used for this is no ordinary leather; rather, it is a high-tech material that is not only extremely durable and washable but also anti-microbial. These qualities are all very desirable when it comes to footwear like Fivefingers. There is a very good reason that the Fivefinger Funk is somewhat infamous, and the kangaroo leather used in the Treks does an excellent job at keeping stench to a minimum. 

Another big difference is the thickness of the mid- and out-sole. On the KSO, you have a 3.5mm out-sole and a 2mm midsole. The out-sole on the Trek is a full 4mm of lugged TC-1 rubber and the EVA mid-sole is also a full 4mm. So, a substantial difference in thickness. 

With that extra thickness you do sacrifice some ground-feel, but it does provide you with better protection against rocks on the trail and street; and against heat and cold surface temperatures. Here in New Mexico, during the summer the pavement can get enormously hot and wearing regular KSO's can be quite uncomfortable. The Trek manages to almost completely mitigate this issue for me personally. And while some ground-feel is indeed lost, I find it a worthwhile trade-off. 

The leather upper also benefits the Trek when worn during the winter or in otherwise inclement weather. It is also quite comfortable even in very warm conditions. I have not found that my feet sweat more than they do in the mesh fabric of the KSO's. The breathability is really quite excellent. 

The KSO Trek is shown here in a side shot that shows the exposed EVA midsole. You can see that as the lighter, greyish-brown material above the black of the TC-1 rubber.

The upper is, as can clearly be seen, almost entirely leather. This upper is vastly more durable than that of almost any other Fivefingers model, short of the newly released all-leather models. The ankle/instep area is gusseted with stretch fabric, which allows for easier on and off.

The sole is relatively heavily lugged, although the lugs on my pair have been worn down significantly. The sole provides excellent grip in most circumstances, especially on soft terrain. 

The toe lugs are especially pronounced and work exceedingly well for gaining purchase while going up steep climbs. 

Despite the thicker sole, the Trek is still very flexible. This flexibility combined with the sole design still allows for a great deal of ground feel, although it is somewhat muted in comparison with the thinner KSO.

Another demonstration of how flexible the Trek is. There is no arch support at all and of course, no heel lift.

The strap arrangement is almost identical to that on the regular KSO. Note that the pull-loop is leather. 

Here you can see the biggest structural difference between the straps on the original KSO and the Trek. The Trek is designed to let you replace the strap. I am unsure though how much a replacement strap might cost from Vibram. 

The toes have panels of stretch fabric in between the toes and on the outsides of the big toe and little toe, respectively. I would vastly prefer it if they used leather here as well. 

Now we come to an area of contention between the Trek and I. On my old KSO's, the velcro strap was long enough to cover all of the exposed hook material, when being worn. Vibram drastically shortened the straps and not just on the Trek. This is how I normally wear them. 

And here the strap is tightened as much as possible. This would not be comfortable for very long for me. The strap really needs to be longer. 

I have worn the Trek in almost any conceivable condition. I've gone off-trail with them in the New Mexican mountains, worn them into abandoned mines, run on both asphalt and trail, used them at work; and traversed the urban landscape with them on a daily basis. They are an exceptionally comfortable shoe and I am a huge fan of the leather upper. It is amazingly durable compared to the mesh fabrics typically used, even when the PU reinforcements that have become common are taken into consideration. Despite the leather upper, the Treks are not waterproof. They do keep the elements out a little better and certainly are warmer in windy conditions, but being as low to the ground as they are, the mesh between the toes does let water in almost immediately. Luckily, they dry fast and as I prefer to wear them with Injinji NuWool socks, the wet-feet feeling goes away quickly. 

But, all is not roses. There are areas where Vibram could make definite improvements. 

One of the biggest challenges for Vibram in the last couple of years has been to just keep up with demand. As word spread, demand for Fivefingers rose so drastically that despite increasing their production capacity over 1800% in the last few years, supply can still be spotty. And this increase in production has come at the price of quality control, which is probably Vibram's biggest weakness at this point. I would strongly suggest buying any Fivefingers at a store that allows for returns if something does turn out to have slipped through quality control. The first pair of Treks that I purchased had a bad seam on the heel pull strap. It came off in my hands only a short time after I bought them. 

Also, as mentioned above, the shortened strap is rather annoying. I understand that not everybody has as tall an instep as I do. Fair enough. But the original straps were designed so that you could easily shorten them without it looking like a complete hack-job. And they were just long enough to work fantastically for us high-volume-foot folks. The biggest part of my annoyance is that it's the hook part that is left exposed by this shorter strap. As you can see in the pictures, the strap picks up all sorts of debris and has to be picked clean on a regular basis. It also has the unfortunate tendency of sticking to certain fabrics. Highly annoying! This really should be fixed. If nothing else, fixed so that it's the soft loop part that is exposed as that won't be so prone to sticking to other fabrics or picking up debris. 

As I mentioned above, the mesh fabric used between the toes and on the sides could stand to be replaced with the leather. Vibram has implemented this on the all-leather Trek LS, but I'd really like to see it done for the KSO Trek. On a recent trip, where I had to walk through some rather dense brush, I had to stop multiple times and pick sharp seeds out from between my toes. The leather would prevent this almost entirely. 

Lastly, I would prefer if the EVA mid-sole material wasn't exposed. As you may be able to see in some of the pictures, it is looking a little frayed. Having that area covered with the much tougher TC-1 rubber would go a long way towards improving the durability of the Trek. If it gets worse, I may purchase some FiveTen Stealth Paint and cover that area with it. 

Other than that, however, the KSO Trek is probably one of my all-time favorite shoes. I find them far more comfortable than the TrekSport, which uses the same sole but replaces the leather with a coconut-based stretch fabric; and just as comfortable as the original KSO. The leather even washes in a regular washing machine just as easily as the fabric Fivefingers and dries quite quickly. 

I fully intend to wear these shoes until they literally fall apart. And I'm not just saying that because I'm cheap... Highly recommended, if you are interested in minimalist shoes, they are well worth checking out.