Vibram’s Trek Ascent Insulated is a fantastic variant of the Trek Ascent for a variety of winter activities. Featuring a wool sockliner that does a fantastic job keeping you warmer than you would expect from a toed shoe, the Ascent Insulated is great for snowy runs, and this new model just might be the most comfortable shoe that Vibram has ever created. Read on for the full review!

About the Trek Ascent Insulated

Here’s what Vibram says about the Trek Ascent Insulated:
Ideal for those who don’t slow down as the weather gets cooler, the Trek Ascent Insulated keeps feet warm while battling the elements. Engineered with an ICETREK outsole, this dynamo provides unparalleled grip and balance on icy cold surfaces.
MSRP at time of review — $130 Weight (Also see comparative model weights listed)
  • 7.44 oz – Trek Ascent Insulated (men’s euro 42) (model reviewed in this post!)
  • 6.60 oz – Trek Ascent LR (men’s euro 41) (reviewed here)
  • 4.06 oz – Bikila EVO (men’s euro 42) (reviewed here)
Total Stack Height — 8mm – 4mm outsole + 4mm EVA midsole (same as all Trek Ascent Models). For comparison, the Bikila EVO WP was 8.5mm Barefoot scale, Ideal Uses — Hiking, trail running, winter road running, light snow work Pros
  • This was a trait that is shared with the Trek Ascent LR
  • Perhaps the most comfortable Vibram, ever
  • ICE TREK compound is great on both trails and good on slippery surfaces
  • Nicely-padded collar
  • Slightly more (!?) flexible than the standard Trek Ascent
  • Adequate cold-weather insulation
  • Toe pockets are roomier than the EVO WP
  • Grooves improve flexibility
  • Good groundfeel for the stack height
  • Good protection from ice, rocks, roots, and branches
  • Traditional laces instead of the superior button and lace system from the Ascent LR
  • NOT waterproof and barely water resistant
  • Fit is slightly different from the standard Ascent LR (42 insulated is LR)
  • Would benefit from a heel pull tab
  • Toes feel “lifted” due to the flex grooves and thick stack height
Sizing — Sizing with the Trek Ascent Insulated is slightly smaller than the Trek Ascent LR. A size 42 in the Ascent Insulated version is somewhere between the Ascent LR 41 and 42. This is most likely due to the added bulk of the wool sockliner and other insulating materials that have been incorporated to the original Trek Ascent platform. Like other Trek Ascent models, the Insulated platform is slightly wider and roomier than the Bikila EVO all around, but the toes feel shorter because of the thicker sole. Unlike the Bikila EVO, which had a bit of a molded interior, the Trek Ascent LR is mostly flat and does not dictate your foot movement as much; your foot is hugged in a fashion similar to the KSO TREK or older Bikila LS.
If you liked the Trek Ascent and Trek Ascent LR, you are going to love the Ascent Insulated with its more comfortable interior and better collar. Here’s a visual walkaround of the Trek Ascent Insulated via photos:


The Trek Ascent and (Trek Ascent LR) has proven itself to be an excellent platform for all-terrain running, hiking, and as a more rugged alternative to the road-centric Bikila EVO, and all-arounder KSO EVO. This is thanks to its wide toebox, versatile tread design, and “middle-ground” stack height consisting of 4mm rubber and 4mm EVA. The Trek Ascent Insulated uses the same exact sole as its popular non-winter brethren, but with subtle tweaks. The Trek Ascent LR feature Vibram’s MEGAGRIP compound in its tread, while the Insulated version uses ICE TREK for superior grip on icy surfaces and lower temperatures.
The very aggressive Trek Ascent tread design
The very aggressive Trek Ascent tread design
At first glace, the ICE TREK sole does not look ant different at all from the MEGAGRIP version. This is unlike the Bikila EVO WP’s ICE TREK sole, which had more texture and detail than the standard Bikila EVO’s MEGAGRIP sole. I was actually expecting the Trek Ascent Insulated’s sole to feature more little dimples, divets, or texture, but I will concede that the Ascent sole design was already the most aggressive of the Vibram’s lineup. What is different is how the rubber FEELS. Much like how a snow tire rubber is different from an all-season tire, the ICE TREK is made for better low temperature performance. It is noticeably softer to the touch and less hard and plastic-like than the MEGAGRIP used in the Trek Ascent and Ascent LR.
As the sole is the same design as the other Trek model, the lugs in the sole are still very aggressive with tons of cleats that are larger in size towards the heel and toe and smaller towards the middle. Each individual lug has a spiked texture and the lugs on the forefoot and toes are angled for uphill surfaces, while the heel section is slightly angled for downhill terrain. Overall, these lugs are more plentiful and more aggressively textured than even the Spyridon MR. The sole features “flex grooves” in all of the toes in a manner that is very similar the Bikila EVO for enhanced flexibility with the somewhat thick sole. These cuts are about 2-3mm deep and allow for easy upward toe flex AND a bit of a downward toe flex. In fact, I found that the Insulated version of the Trek Ascent to be more flexible than the Trek Ascent LR that I tested last year. This was completely unexpected and a pleasant surprise considering how Vibram’s last winter mode, the Bikila EVO WP, was much more inflexible and cramped than the non WP platform that it was made from. While in the Trek Ascent LR, I was not able to flex my toes downward, I was able to a small degree with the softer ICE rubber in the Ascent Insulated. The aggressive sole, ICE TREK compound, and flex grooves make the Trek Ascent Insulated an excellent winter trail hiking and trail running shoe. Having individual toes gave my more dexterity and control over closed-toe trail shoes and huaraches. This added sensitivity can spell the difference between a slip or a clumsy recovery during snowy runs.
The Trek Ascent sole with ICE TREK rubber: Flexible and grippy for winter running
The Trek Ascent sole with ICE TREK rubber: Flexible and grippy for winter running
Overall, it’s a great sole; grippy due to its rubber compound, lugs/cleats, and tread pattern and provides plenty of protection, while still giving you the benefits and flexibility you come to expect from a Vibram shoe. The deep lugs can handle a bit of snow before slipping and the ICE TREK compound performs marginally better than the standard MEGAGRIP for cold weather activities. Unlike the Trek Ascent and Ascent LR, I would recommend these for road running when there is a bit of snow as the lugs make a huge difference in the winter, while those same lugs were a hindrance for road running in the summer.
A primal footprint. There must be a fast yeti somewhere in beantown
A primal footprint. There must be a fast yeti somewhere in beantown

Fit and Materials

High Tenacity Nylon + Polyester + Wool sock liner The Trek Ascent Insulated feels like a plushy and premium product in the Vibram lineup and sets a very high bar for materials and an overall comfort. It feels substantially more comfortable than the LR and is arguably the most comfortable shoe that Vibram has ever made. Your foot is cushioned all around with a nice wool sockliner and the uppers are made of a soft water resistant nylon to keep the wet stuff out…for a little while at least.
I absolutely love the padded heel collar and tongue of the Trek Ascent Insulated. If you were a fan of the padded collar of the original Bikila and Bikila LS, you will absolutely love the extra comfort and security that the Trek Ascent Insulated provides. This is a nice contrast to the Trek Ascent LR, which had some people complaining about its scratchy, high-set collar. The Trek Ascent Insulated feels like your favorite winter blanket is hugging your foot.
The ankle collar in the Trek Ascent and Trek Ascent LR was a bit irritating for some folks as it rode slightly higher than other Vibram models. The issue was mainly isolated to talus–the bone that sticks out to the sides near the hinge of the foot. With the Trek Ascent Insulated, you will have a talus.
The padded collar keeps stuff out, maintains warmth, and is very comfortable
The padded collar keeps stuff out, maintains warmth, and is very comfortable
The Trek Ascent Insulated eschews the awesome lace system of the Trek Ascent LR for a traditional lace system. These laces are super thick and plushy for really strong tying, but I prefer the bungee and velcro lace system of the Trek Ascent or the reinforced bungee and button variation in the LR.
 Cold-weather-ready Trek Ascent Insulated with the fairweather Trek Ascent LR
Cold-weather-ready Trek Ascent Insulated with the fairweather Trek Ascent LR
The footbed in the Trek Ascent Insulated is the same as the non-insulated variations and can be characterized as…squishy. This 4mm footbed is not removable and while other Vibram soles may have similarly thick EVA, the Trek Ascent’s EVA is more plush and forgiving than other shoes in the lineup. This soft footbed is well-advertised by the aforementioned “soft” button on the bottom of the sole. The overall ground feel is more diminished as a result of this soft footbed and thick sole; a degree less than the thicker-stacked Bikila EVO (8.5mm vs 8mm).
Trek Ascent LR and Trek Ascent Insulated. Note the difference in collar padding and lace system vs traditional laces
Trek Ascent LR and Trek Ascent Insulated. Note the difference in collar padding and lace system vs traditional laces
In my testing of the Trek Ascent Insulated, the wool sockliner does an admirable job at keeping my feet warm. During a snow day in Boston, I went for an 8-mile run through snowy roads and trails and my toes did feel a little cool, but never froze (completely different from my experience in the non-insulated, yet waterproof Bikila EVO WP). Because barefooters typically run sockless and this is a toed shoe, Vibram had a difficult problem to overcome with keeping all of our toes cozy in freezing temperatures. The wool sockliner, “high-tenacity” nylon, and polyester uppers do a very good job of keeping everything relatively warm for my runs in the snow—definitely warmer than any other Vibram shoe to date.
Trek Ascent Insulated vs Bikila EVO WP: The Trek is warmer and more capable, while the WP is truly waterproof, but less flexible and colder
Trek Ascent Insulated vs Bikila EVO WP: The Trek is warmer and more capable, while the WP is truly waterproof, but less flexible and colder
The wool sockliner is also very sweat-friendly! Unlike many fibers, wool readily absorbs moisture better than most fabrics. I was very surprised to find my feet NOT feeling like a swamp after my runs during snow days despite being pretty warm in temperatures ranging from 20-30 degrees Fahrenheit.
Wool all around
Wool all around
The water-resistant nylon and wool combination was pretty good for keeping out the cold and keeps the wet stuff at bay, but it does not last forever. Eventually, water can get through the layers of nylon and wool to reach the poor piggies underneath. Provided you avoid puddles or very deep snow, you should be just fine. Unfortunately, this is an insulated shoe, NOT a waterproof shoe. In terms of stack height, it does not take very deep snow to sink the uppers past the protective rubber and as snow contact increases over a long run, you can get water inside the toe area. The rest of the foot remains pretty dry throughout and it is always the toes that get wet first. As a test, I stood in a puddle of icy water and the shoe gave me about five seconds of protection before I felt the water begin to soak in. The low collar suggests that this is not a deep snow shoe and it really is not meant to be used as such. I would say that this is great for trails and road running that is around an inch of snow or less. Provided you are running in places that are routinely plowed or shoveled, you will have a good time; venture too deep into icy territories and you will find yourself with a case of cold feet.
The rubber lugs will provide roughly 4mm of lift before you start soaking the water-resistant, but not water-proof, uppers
The rubber lugs will provide roughly 4mm of lift before you start soaking the water-resistant, but not water-proof, uppers
Together, the 4mm tread and soft 4mm footbed provide a good amount of protection with tough terrain and helps keep things a bit less jarring upon landing. The groundfeel should be plenty for most new runners, while giving enough protection to learn proper form. You will still feel rocks and awkward ice patches, but there is enough plush and protection to keep your foot safe, yet enough transmission of textures and impact to keep your eyes looking forward for obstacles and good trail-running technique. Strangely enough, Vibram removed the pull tab from the Trek Ascent and Trek Ascent LR when they designed the Insulated version. A pull tab would have been very help to aid in taking the shoe on and off as it is a slightly more substantial shoe than the other Treks, which takes a bit more time to fit. I believe that a pull tab should be mandatory for all shoes from Vibram as they really do make wearing them so much easier. I also think that every shoe should padding of some sort around the collar and tongue, just like with the Bikila LS and Trek Ascent Insulated. It really makes the shoe feel more locked in and comfortable as you move around.


In the Vibram lineup, this is one of my favorite shoes because the Trek Ascent Insulated is so comfortable and does a great job for winter running. Vibram has attempted to create a premier winter shoe for a while with the Lontra and Bikila EVO WP, but I think that the Trek Ascent Insulated is the closest to hitting the mark. I am hoping for a truly insulated, capable, and waterproof shoe, but the Ascent Insulated strikes a balance between comfort, grip, and polish that few minimalist shoes can provide for winter fun. If you want a minimalist shoe for the winter and are not expecting to encounter deep snow, this is the running toe shoe for you. Check them out for yourself and enjoy the nice wool hug! NOTE: Looks like the Trek Ascent Insulated is a little hard to find right now. One place that has at least a few sizes available is EMS.