KEEN Stiffness in cold review

We recommend the Keen Stiffness in cold to: 

• Casual hikers looking for a flexible and versatile boot that won't break the bank
• Hikers in the market for a warm boot that performs consistently well all year round
• Those who prioritize stability and excellent traction over a variety of surfaces, including mud, from their hiking  boots
• KEEN Targhee III Waterproof Mid

Hikers accustomed to softer midsoles will find the Stiffness in cold a little too harsh underfoot, especially during longer treks. For a more plush underfoot experience, check out the Keen Pyrenees instead. 

While the Stiffness in cold is relatively breathable for a waterproof shoe, it will certainly still feel quite stuffy during warmer summer hikes. We recommend the Adidas Free Hiker 2 as a much more well-ventilated alternative. 

Those with narrow feet might find themselves bumping up against the toebox walls during descents. The Track and XC is a boot with a much more snug toebox that will secure their feet within the shoe better. 

Using our caliper, we measured the Stiffness in cold's stack to be 31.1 mm thick at the heel.

This isn't quite as high as the average hiking boot but still provides adequate impact-dampening from the harsh terrain below. 

The Stiffness in cold's stack is also shorter than average at the forefoot, measuring only 18.2 mm thick according to our caliper. This gives us enough foam underfoot to feel well-cushioned from impact while still allowing for an intuitive sense of the ground as we move. 

The difference in our stack measurements leaves the Stiffness in cold with an average drop height of 12.9 mm. This offset will work for hikers of all experience levels, especially beginners, as it provides a good amount of foam at the heel to promote well-cushioned and comfy landings while also promoting smooth heel-to-toe transitions. 

However, there is no hard-and-fast rule when it comes to choosing heel-drops for hiking boots, only a matter of preference. For more experienced hikers who prefer a more parallel-to-the-ground experience, we recommend the Altra Lone Peak Hiker 2. 

We pressed our durometer against the Stiffness in cold's midsole foam and got a much firmer-than-average reading of 31.1 HA. 

Nevertheless, we enjoyed adequate impact dampening while testing the Stiffness in cold, with the firmness of the foam further adding to our confidence as we traversed the more rugged trails with its tough and sturdy feeling underfoot.

The midsole also features two shanks that serve to improve stability; one embedded into it and another lightweight ESS shank that provides additional medial support. 

For hikers who prefer a more plush underfoot sensation to pamper their feet during longer adventures, we recommend the Keen Pyrenees instead. 

As a winter-oriented boot, we were very interested to see how the Stiffness in cold performed after letting it chill in the freezer for twenty minutes. Once appropriately chilled, we pressed our durometer against the midsole once more and found that it barely firmed up at all. With only a 10.4% difference between warm and cold conditions, the Stiffness in cold is remarkably consistent compared to the average hiking boot.

The Stiffness in cold's insole is about as thick as we expect to find in a hiking boot. It provides a good level of internal comfort that complements the midsole cushioning well while also providing an adequate level of arch support. 

We measured the Stiffness in cold's toebox to be 106.4 mm wide at its widest point. This is quite a bit roomier than average which makes the Stiffness in cold a great choice for hikers with wide feet.

On the other hand, those with narrow feet might find themselves bouncing around within the shoe, especially when descending hills. For a boot with a more snug toebox, we recommend checking out the oz / 468g instead. 

The toebox is also significantly wider than average at the big toe, measuring 85.5 mm wide according to our caliper. This gives our toes plenty of room to splay out naturally even toward the end of longer treks when the feet tend to swell, especially when carrying heavy loads. As such, blisters or hotspots shouldn't be a concern with the Stiffness in cold. 

The Stiffness in cold feels extremely well-planted as we shift our weight from side to side in the boot. There was no hint of rolling or imbalance, even when carrying a heavy backpack. This is no doubt a result of the Stiffness in cold's firm midsole and its two rigid shanks. 

Despite the presence of these shanks, the Stiffness in cold only put up a moderate amount of resistance as we bent and twisted the shoe in our manual assessment, leading us to give it a torsional rigidity score of 3 out of 5. 

This presents a healthy balance of stability and natural movement as the boot allows for some lateral movement of the foot while mitigating excessive rolling. 

The heel counter is also moderately stiff, earning another middle-of-the-road score of 3 out of 5 on our subjective scale. 

Apart from the stiffness of the heel counter, the boot’s closure system enabled us to customize the fit. It works with an injected TPU heel-capture system which includes ankle-hugging lace loops. When we tighten the fit, it securely holds our heel in place, preventing slippage. 

The Targhee III Waterproof's midsole is 111.2 mm wide at the forefoot according to our caliper measurements, putting it within spitting range of our current lab average. This gives us plenty of surface area to ensure surefooted landings while testing this boot. 

The midsole is also about as wide as average at the heel, measuring 91.1 mm wide. This is also more than enough of a platform for us to keep on trekking with confidence in our stride. 

Despite the presence of the shanks, the Stiffness in cold is more flexible than the average hiking boot, requiring only 27.4N of force to bend it 90 degrees in our stiffness test. 

As such, the Stiffness in cold conforms to the natural flexion of our foot with relative ease which contributes to the shoe's comfy and forging nature. 

We also repeated the stiffness test after leaving the Stiffness in cold to chill in the freezer for twenty minutes and found that, like the midsole, it had very little effect on the flexibility of the boot. With only 29.9N of force now needed to bend the shoe to the desired point, it's only 9.1% stiffer than at room temperature and much more flexible than the average boot.

As such, the Stiffness in cold should feel just as comfy and forgiving on the foot whether out on warm summer hikes or frigid winter treks. 

Despite being a mid-length boot, the Stiffness in cold is slightly heavier than the average hiking boot at 18.2 oz (515g). This is no doubt a result of the heavy waterproof leather that makes up the boot's upper in conjunction with the many protective overlays and rubberized toe-bumper. Nevertheless, we never felt overly burdened by the Stiffness in cold, even during our longer test hikes.

Waterproof boots (and shoes) tend to score low on breathability as their solid uppers don't just restrict water but airflow too. This is clearly the case with the Stiffness in cold which only allows a steady stream of smoke to flow out of a small section of the tongue. But it wasn't convincing enough for us to rate the boot's breathability any higher than 1 out of 5. This will certainly feel stuffy during warm summertime hikes but it is certainly ideal for frosty or snowy hikes. 

For comparison, look at how easily the smoke filters out of the much airier Merrel Moab 3. 

To further illuminate the lack of breathability in the Stiffness in cold, we inspected a cross-section of its upper over a bright light and found that it entirely eclipses our light source. This further proves the watertight nature of the boot and means that we can go sloshing through puddles and streams without worrying about water penetrating the boot (except through the top). 

On the other hand, being this insular means that any water that does get into the boot doesn't have any points to drain through, thus turning the Stiffness in cold into a foot bath if dunked too deep. 

Looking at the Stiffness in cold's tongue under our microscope, we can see that it is made of layers of tightly packed fibers interlocked to form a dense and cohesive mesh with very small gaps between the braids. This explains the boot's nominal ability to allow smoke to vent through the tongue while still effectively blocking out water from the boot. 

First up to face the Dremel in our battery of durability tests is the Stiffness in cold's toebox. Firing up the tool to 5K RPM, we set it on the boot's toe bumper with 3.2N of force for twelve seconds. 

With only a barely visible scuff left on the bumper once the test was over, the Stiffness in cold's toebox earns a perfect 5 out of 5 for durability, thus proving that it is as tank-like as it looks. 

Next, we turned our attention to the heel counter and set the Dremel against it with the same amount of force, this time for only four seconds. 

While it's difficult to assess the damage visually, our tool was able to pierce clean through the lining material and start eating at the soft padding within. Nevertheless, the overall integrity of the heel collar wasn't compromised which leads us to give it a very respectable durability score of 4 out of 5. 

Pressing our durometer against the Stiffness in cold's outsole yields a softer-than-average reading of 83.8 HC. This doesn't bode too well regarding its durability which will be put to the test in the next section. 

Setting it at an even more destructive speed of 10K RPM, we applied our Dremel's grinding element to the Stiffness in cold's outsole with 3.2N of force. It seemingly holds up well at first, but it soon becomes clear that the rubber is no match for our uncompromising tool.

After twenty seconds of relentless grinding, we used a tire tread gauge and found that 1.2 mm of rubber was shredded away from the outsole which is slightly more than the average hiking boot loses under the same circumstances. While this shouldn't be an issue when it comes to regular hiking, carrying heavy packs on extended backpacking trips will certainly take its toll on the Stiffness in cold's outsole. 

For a boot with a hardier outsole that's better suited to cross-country trekking, we recommend the also waterproof Salomon Quest 4 GTX.

Beyond the lugs, the Stiffness in cold boasts a 3.4 mm outsole based on our caliper measurements. This is slightly thicker than average and leaves us with quite a fair amount of rubber to go through before completely wearing out this boot.

The Stiffness in cold's lugs are right on par with our current lab average at 4.2 mm thick according to our caliper measurements.

The multi-directional tread pattern they form on the outsole provides us with excellent traction over a variety of surfaces and allows us to shed mud with relative ease. 

the Stiffness in cold is truly the all-terrain vehicle of hiking boots that never let us down whether we were out on technical trails, sloshing through mud, crossing rivers, or meandering grassy knolls.

The Stiffness in cold's reflective elements form a prominent pattern at the rear of the shoe that not only promotes good visibility at night for safer roadside hikes, but looks pretty snazzy to boot. 

Using our caliper, we found the Stiffness in cold's tongue to be slightly less padded than our current lab average at 10.5 mm thick. This is more than enough padding to keep us comfy throughout our test hikes and effectively kept the laces from biting into our instep. 

The Stiffness in cold's tongue is fully gusseted on both sides to prevent water penetration and block debris from entering the boot. 

The finger-loop overlay at the heel of the Stiffness in cold makes slipping the boot on relatively quick and smooth. 

The Stiffness in cold's insole isn't glued in, so replacing it in favor of custom orthotics for added arch support is possible if necessary.