Karhu Flow 3 Trail Review

First Impressions:

Upon receiving the Karhu Flow 3 Trail shoes I was immediately struck by the box colors of gold and black highlighted with a description of the “fulcrum technology” integrated into many models of the Karhu running shoe line.

Myself, I love the look of the shoe. It is neither flashy, nor imprinted with needless bling or highlights to dress it up- just the Bear logo, Karhu name, and “fulcrum” decal impregnated into the midsole in the appropriate area. The shoe feels solid, yet surprisingly flexible for a trail shoe. It isn’t super lightweight but certainly within acceptable limits for a good quality trainer.

The Karhu brand has long been a part of my life, albeit in the ski and boot arena. Given that the reputation for high quality and durability from Finland is already ingrained in me from the outset. I spent many years traversing the alpine and nordic terrain of Stowe Vermont often utilizing both classical and backcountry gear from the “bear” of Finland.


I like to start here because when running in a trail shoe I want to be sure of grip, yes, but also, I really don’t want to be doing extra weight work by carrying the trail with me. So often shoes have oddly placed, arranged, shaped lugs, patterns and cracks that trap small stones, sticks, extra mud and the like- the Karhu Flow 3 Trail has none of that.

The sole here is a base of blown EVA with hearty patches of compression molded high abrasion rubber lugs for gripping and wearing. The company calls these grippers counter-directional “t-lugs” designed to be great up or down hill, as the Fins understand, one begets the other on most of the planet.

Well, the t-lugs are a sweet set up. The fronts angle just slightly back for gripping on the ups and forward propulsion of course. The rear t-lugs angle forward a bit providing a grab on the declines when one so chooses. If you are just letting it fly on the downs there is nothing slowing you down- the overall base is relatively flat but gets a good bite for sure.

I have been able to attest to the hold of the outsole on the following surfaces with great results so far: grass, packed dirt, loose dirt, sand, rocky & rooted trails, rock covered steep grades sometimes wet. I have not yet had the opportunity to test stream beds or thick and gooey mud. When I do, I will update the post accordingly.


The midsole is two different densities of EVA- the primary being a black softer version from toe to heel located below the denser “fulcrum” level of yellow encompassing the heel counter and flowing forward to the front of the arch area. This Fulcrum Technology is a feature Karhu integrates in to the entire line. The data suggests that it assists the runner with forward momentum vs. vertical movement- I’m a fan of that for sure. Fortunate to have decent form and didn’t notice the difference, but I doubt it’s a gimmick. Karhu supports many serious athletes.

I find the midsole combination of the Karhu Flow 3 Trail to be pretty efficient. I like the firmness of the lop layer in the zone of my heel, yet the base layer of VEA seems to absorb the little things on the trail- thereby diffusing the impact including roots, sticks, rocks fairly well.


This is yet another basic sock liner variety- no extra arch cookie or anything. Even the shoe itself is not putting much emphasis on the arch outside of being shaped to fit the anatomy of the foot. This is great as far as I’m concerned, don’t really enjoy arch support, and allowing the foot to regulate this is probably the best way to prevent some basic injuries.

At this point, I might also mention that inside the heel cup are two bumps to either side of the achilles tendon that protrude (by design) apparently to hold the heel in place during a run. Honestly, I wasn’t sure what to make of this, but once the shoe was on, I never even noticed it and haven’t yet. I can only imagine this would have been a plus back in grade school to prevent the pranksters’ “flat tire” trick, but an untested theory so far.


The upper is a simple, yet interesting layer combination of materials. The exterior has a meshy pattern allowing a fair amount of stretch in every direction- but only to a point. This mesh firms up once the slack is taken up making it fairly good support even laterally. The inner layer is a much finer weave that has even less pull. The combination provides for a surprising level of support without restriction.

The lower layer on the outside of the upper is a denser formed material with some level of dirt repelling, which might keep fine grit and sand from seeping into the footbed keeping you comfortable longer in dusty conditions. The stitching is a “Z” pattern between the materials and does not protrude at all, so no catches on shrubs and weeds along the trail. Quite nice.

This stitching methodology is also evident on the inside of the upper- with virtually no rub at all, which makes this a candidate for sockless runners. The style and function of the Flow Trail 3’s upper is excellent and I look forward to cranking a few hundred more miles on these babies to see how they hold up.

One thing that was sort of a surprise was that the inside of the Flow 3 Trail bled a blueish color onto my socks for the first few runs. I started the trial with a new pair of Injinji Lightweight No Show socks in gray. They are still discolored after several washings. The second pair I used was the Balega Hyper Thin sock in white- which even after a few runs the shoe still bled on them a bit. No big deal for me, but for some of you more fashion oriented folks, it could cramp your style.


The heel integrates yet one more layer on the inside, a softer padded style mesh tightly woven and wickable for pulling moisture away from the sock.

Again, I will mention the bumps on either side of the achilles. Haven’t noticed these while running, but I do have a pronounced heel. I worry about the rubbing, but so far so good. Otherwise, the heel has a very basic collar straight up no pillows or tightness at all, that I like.

Toe Box:

The toe box is relatively low cut and symmetrical, including reinforced material right where it could bump or snag something along the trail- offering some extra protection. The toe box is a bit straight and narrow. I find it very similar as the Saucony Peregrine 2 feel, only not as restricting- the mesh materials on The Karhu Flow 3 Trail are much better ventilated.


The Tongue is constructed from the same materials inside as the lining in the heel. On top, it sports the same wider mesh as the upper- only in yellow here. This is a classic tongue, mounted below the lacing system at the toe box and free to roam with the exception of a well placed eyelet 3 lace sets up. It stays in place and it is quite comfortable. No snags here.


The lacing is a straight pattern of six on each side, with a seventh set back a tad into the heel collar area for those who like to bind them up tight. The eyelets are cut through the upper material, which is reinforced from behind with a strip of rugged poly-ish material. Each eyelet is stitched for added reinforcement. The laces provided are oval nylon variety, black in color which matches the shoe, of course.

Usage So Far:

Have had a fair chance to put the shoe through it’s paces- at least the way I tend to train. Number one for me is a good ride on a variety of crushed gravel. On the gravel roads I predominantly train, the size of the stones vary significantly size-wise from peas to ping pong balls and in all shapes imaginable. I should point out, I am in Idaho where all the gravel is crushed rock, so pointy edges galore. I grew up in New England where the gravel is natural glacial deposits and simply sifted by stone size, smooth stones for the most part- big difference. So here in Idaho, many outsoles grab chunks of rock, and when you transition back to pavement it’s like wearing a mutant tap shoe- the Karhu Flow 3 Trail sole is awesome- no chunks, grit, sand, nothing- smooth and enjoyable.

Regular trails of dirt have been a breeze too- good response, good grip, cool and smooth to run in at any pace. Handling regular roots and stones in this environment is no problem at all. In more challenging, loose shaky stone they perform as expected. No shoe makes this easy, but I never felt that the shoe impaired my ability to navigate the trail.

I also love to get cruising on good ol’ fashioned grass- be it an athletic field or in my case, open meadows with a variation in pitch and roll- all good with the Karhu Flow 3 Trail.

On the road, this shoe transitions to pavement and concrete very well. I mentioned that there is never any crap stuck in the soles, which is most important because I hate stopping to clean out my shoes to avoid the annoying clicking you get when debris is in the outsole. Beyond that, the shoe cruises nicely in all conditions I’ve expereinced.

Even after a few miles on the track, I wouldn’t consider this shoe my top choice for interval work, but I wouldn’t be afraid to us the shoe either. I happened to be doing some trail work, poached some golf course, got chased off and wound up on a local track to finish up, no problem outrunning the golf cart ;-).

UPDATE: Took a Sunday long run in the Karhu Flow 3 Trail, mostly gravel roads, some pasture edges and such too- just over 18 miles and felt great on the feet, even in the heat.

Closing Impressions:

I really like the shoe. As mentioned, I train on gravel a lot and it is a good solid performer for this need. I also try to get on grass in a local arboretum with lots of strange angles and steep terrain (near the golf course). On regular trails, including the standard rocks, roots, loose and packed dirt it was a flawless shoe. On anything like loose rock, large rock slabs, or more technical terrain it was more than ok. I have to say I like the Merrel Ascend Glove on the rockier terrain as it sits closer to the ground. However, the Merrell is a zero drop with far less midsole material for protection so it isn’t really a direct comparison as the Karhu has about a 6mm offset from heel to toe and 23mm of midsole too. I love the switch up between these two shoes for most of my runs on appropriate surfaces.

Overall the Karhu Flow 3 Trail is a genuine and solid running shoe. I like the no frills, high quality build. I feel like I can attack almost anything with these- even roads feel nice. I do hope to get a crack at the Flow 3 trainer or even the Flow Light in the near future- maybe both. Don’t overlook Karhu because you haven’t heard much about them. These are very well designed running shoes. I’m proud to support Karhu as they have always been very committed to producing great products for serious athletes. Karhu has been around since 1916 (Karhu History) and is no slouch when it comes to quality athletic footwear. Finland is a country where the running tradition is very long, strong and impressive.

The shoe weighs in at 11.1 oz on my kitchen scale in size 13. Yes, I do have some bigger hooves for sure, my weight is in the 160lb range, so I’m light on my feet for my 6’4” frame…

View the Flow 3 Trail at Karhu.com

Description from Karhu:

Rugged enough for the toughest single track trails, yet accommodating to road surfaces, the Flow Trail features a counter-directional T-lug design equally adaptable to both uphill and downhill running. The lower profile maximizes the feel of the terrain without compromising the Fulcrum Technology’s ability to increase propulsion. A durable waterproof mud guard protects the runner’s feet from harsh wilderness elements including creek crossings, rocks and roots while the faster transition through the gait-cycle makes it easier to flee from angry moose.


  1. Anatomically sculpted air mesh for maximum ventilation combined with a highly abrasive and water resistant side vamp wall.
  2. Gusseted tongue is anatomically mapped around the instep and features a soft touch logo top.
  3. Welded eyelets and reinforced forefoot weld.
  4. EVA padded lasting board.
  5. Dual-pronged memory foam heel collar.
  6. Moisture wicking collar liner.


  1. Lightweight, breathable and with strong mid foot support and protection from the trail elements while still allowing evaporation.
  2. Keeps dirt out and ensures the laces form correctly over the foot.
  3. Lightweight and durable ensuring a proper fit by resisting up and down hill pressures .
  4. Locks heel comfortably in place.
  5. In-shoe moisture management.


  1. Precision engineered compression molded EVA midsole with tuned durometer hardness.
  2. Directly placed EVA Fulcrum: 70 durometer.
  3. Compression molded EVA insole.
  4. Expanded zones of compression rubber in counter grip pattern with center deflection channel.
  5. Lateral fulcrum reflectivity.


  1. Provides ultimate forward efficiency.
  2. Propels runners transition onto their forefoot and into toe off efficiently, reducing breaking forces and heel drop in the landing phase.
  3. Arch support, moisture management step-in feel.
  4. Lightweight, proper up hill and down hill grip for back country conditions.
  5. Essential visibility against angry Moose.


  • 9.0 oz (255 g)


  1. Upper
  2. Logo
  3. Lining
  4. Midsole
  5. Fulcrum Technology
  6. Outsole


  1. Air mesh and ballistic synthetic
  2. Textured synthetic wicking and ventilating liner
  3. 56 durometer EVA
  4. 70 durometer EVA
  5. Compression molded high abrasion rubber, counter grip molded.

View the Flow 3 Trail at Karhu.com

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