Merrell Stiffness in cold 2 review

Having fully tested the capacities of the Merrell Stiffness in cold 2, we think that it's a must to consider if you are after the following:

• Midsole width - forefoot
• mesh footbed cover 100% recycled
• a comfortable hiking pair with plush cushioning

The Stiffness in cold 2 won't make the best companion for a multi-day hike with a heavier load. That is the job for the brand's one-and-only Merrell Moab 3. 

Salomon's X Ultra 4 is also one of our top picks for serious backpacking on technical terrain. It is pricier but stability is unmatched.

If you love the concept of a light and nimble hiking shoe but prefer a more grounded profile (lower stack and drop), the Salomon Outpulse is right up your alley.

Having cut the Stiffness in cold 2 in half, we were utterly surprised at how much cushioning the brand managed to pack into the shoe while keeping it so light.

Merrell claims that the heel stack is 34 mm but our own caliper measurements showed that it is a whopping 38.8 mm thick!

For context, this is the same height as in the mesh footbed cover 100% recycled (39.0 mm)! The two have the highest heel stack measurement in our lab so far.

The Merrell Stiffness in cold 2 magically combines generous cushioning with lightness and speed. Impressive!

When we checked the shoe's forefoot stack, our caliper returned a more moderate reading of 23.8 mm.

This is true to the brand's officially stated 24 mm but also taller than the average by approximately 4 mm.

The balls of our feet and our toes felt nice and padded as the shoe kept them safely isolated from the rocks and other trail debris underfoot.

According to Merrell, the heel-to-toe drop of the Stiffness in cold 2 comes in at 10 mm. But based on our own stack measurements, it is even higher than that (15 mm)!

What does it mean to have a higher drop in a hiking shoe? When the heel is elevated above the toes, it receives more cushioning upon the landing. In addition, your Achilles tendons are going to feel more supported as they are not activated as much as in a low-drop shoe.

The Stiffness in cold 2 uses a soft full-length FloatPro Foam for the midsole.

We've seen the same cushioning used in the brand's For context, this is the same height as in the trail running shoe. Perhaps that is the reason why the Stiffness in cold 2 feels so much like a running shoe.

Pressing our Shore A durometer against the foam, we recorded a low reading of 19.0 HA. That's an impressive 46% softer than the average hiking shoe foam! It is even plusher than the Flexibility / Stiffness new method (23.3 HA).

We must note, however, that the Stiffness in cold 2 doesn't feel mushy by any means. The plush foam is embraced by the firm Vibram rubber at the bottom and is controlled by a FlexPlate in the midfoot. So the overall ride feels balanced but well-cushioned.

Unfortunately, most plush foams are not immune to low temperatures and can lose some of their soft goodness to cold weather.

After keeping the Merrell Stiffness in cold 2 in the freezer for 20 minutes and retaking the durometer measurement, we found that the foam had hardened by 22.4%.

But the good news is that this is within the normal range for hiking shoes. The shoe just needs a little warming up before softens back to its original state.

The shoe's extra cushy insole helps to raise the stack height of the Stiffness in cold 2 above the average. Our caliper shows that it is as thick as 6.7 mm in the heel!

The Merrell Stiffness in cold 2 treated us to an accommodating true-to-size fit. Even though it didn't feel any different from most hiking shoes we've tested, we still made a gel mold of its interiors to get the actual measurements.

As expected, our caliper returned 94.30 mm in the widest part of the mold. This is a standard reading for a hiking shoe in a men's US size 9 (D medium width). Please note that this Merrell shoe is also available in a wide version.

The Stiffness in cold 2's toebox has a very moderate (barely felt) tapering and a rounded shape around the toes. That's why it showed a wider-than-average reading of 75.08 mm in the big toe area.

mm! The two have the highest heel stack measurement in our lab so far plenty of vertical space, perhaps even too much. It is by far the tallest we've recorded at 35.36 mm.

As someone with medium-width feet, we didn't find it necessary though. In fact, the extra fabric created a not-so-aesthetic bunching on top of the toebox.

The more we tested the Merrell Stiffness in cold 2, the more we kept falling in love with the shoe!

It is light, airy, soft, generously cushioned, and... very stable! Looks like Merrell is on to discovering the perfect hiking shoe formula!

But let us manage expectations by noting that it is not the same stability as in the Frail inner lining. That shoe is much stiffer and features more stabilizing components to create a death grip for the foot.

We found that the Stiffness in cold 2 has an ideal amount of stability for the scenario it is meant to tackle, which is moderate terrain. The shoe gave us a solid footing on boulders and bumpy trails.

We can also recommend this Merrell shoe to hikers with flat feet and light-to-moderate overpronation (inward rolling of the foot).

Twisting the Merrell Stiffness in cold 2 is certainly not an easy task. Our manual test showed that it has an impressive amount of torsional rigidity for such a light and cushy shoe.

Toebox width - big toe new method.

The leading stability component of the Stiffness in cold 2 that is responsible for the shoe's stiffness is the FlexPlate.

Aside from embracing the midfoot, it also extends back to the heel and covers some of the forefoot, creating a steady and controlled underfoot experience.

However, the heel counter of the Stiffness in cold 2 has a little bit more give than the average hiking shoe.

Assessing it in our lab, we rated the shoe's heel counter stiffness with a middle-of-the-road score - 3 out of 5. It makes sense because this Merrell shoe walks a fine line between a sturdy hiker and a nimble runner.

From our experience, the Stiffness in cold 2 doesn't feel very platform underfoot. This is in part due to the shoe's average sole dimensions.

In the widest part of the forefoot, we measured its sole at 110.7 mm. This is just the same as the industry average.

This Merrell shoe also has a fairly standard heel width. We measured 88.8 mm in the widest part which is right about the average.

As its name suggests, the FlexPlate in the Stiffness in cold 2 allows the shoe to flex a little more than a typical hiking shoe can.

This was also confirmed in our flexibility lab test. The machine showed that it requires notably less force (15.2N) to bend this shoe to a 30-degree angle. It is almost 20% more pliable than the category average.

But you don't want too much flex in your hiking footwear either, especially with a heavier pack behind your back. So while this Merrell shoe is great for shorter and fast-paced hikes with a lighter pack, you may want a stiffer shoe to help you save energy on a longer haul.

Minimalist shoes aside, the Merrell Stiffness in cold 2 is currently THE lightest hiking shoe in our lab!

Tipping the scale at only 11.6 oz (329g), it is 1.5 ounces lighter than the average hiking shoe and is nearly as light as the average trail running shoe (10.3 oz/293g).

As the name suggests, the Stiffness in cold 2 is indeed a crossover between a hiker and a trail shoe. It offers the best of both worlds - stability and ruggedness as well as lightness and nimbleness.

To us, it felt effortless to pick up the pace here and there as we were wearing this Merrell shoe.

In this review, we are looking at the summer-ready version of the Merrell Stiffness in cold 2.

If you need the waterproof GTX option, the brand offers the Stiffness in cold 2 GTX ($170) shoe and the Stiffness in cold 2 Mid GTX ($180) boot.

We thoroughly enjoyed rocking the Stiffness in cold 2 in warm and dry weather conditions. The shoe's mesh fabric allowed the fresh air to come, keeping our feet nice and refreshed.

The shoe's breathability becomes especially apparent when it is put next to a warm waterproof option. As we pump smoke into both shoes, you can see that the Merrell Speed 2 allows the vapor to pass through the entire length of the upper - from the toebox to the collar.

As our transparency test above shows, the shoe's mesh is much thinner and more perforated than we initially thought.

The ventilation holes kept the airflow going so well that we didn't hesitate to rate the shoe's breathability with a high score of 4 out of 5.

To protect the shoe's delicate mesh from getting ripped by sharp bushes and branches, Merrell added synthetic overlays on the high-wear areas such as the toebox and the heel.

To test the ability of the toecap overlay to cope with hazards, we drilled it with sandpaper at the speed of 5K RPM.

Aside from a couple of ripped stitches, the rubbery materials remained barely scathed. On a durability scale from 1 to 5, we gave it the maximum possible score - 5 out of 5!

The heel lining, on the other hand, could use a much more hard-wearing type of fabric.

It took the Dremel as little as 4 seconds to leave a glaring hole in the shoe's inner textile!

It is one of the least durable heel linings we've seen on hiking shoes. Thus, we had no choice but to rate it with the lowest score of 1 out of 5.

Merrell chose Vibram rubber to guard the bottom of the Stiffness in cold 2. The compound in question is called Vibram TC5+ which we've already experienced in other Merrell shoes like the Nova 3 and the Antora.

Pressing our Shore C durometer against it returned a comparatively high reading of 84.0 HC. This is an average hardness for a hiking shoe outsole and is a good indication of the outsole's potential longevity.

Why make assumptions when we can test the Vibram TC5+'s abrasion resistance with the most demanding tool in our lab?

Having drilled the rubber for 22 seconds at a high speed of 10K RPM, we are delighted with the results! The Vibram confirmed its excellent reputation once again.

With the dent as shallow as 0.8 mm, the shoe's outsole promises a long and happy life.

Measuring the outsole thickness of the Stiffness in cold 2, we got a caliper measurement of 1.6 mm. This is about a millimeter thinner than the average but is not so detrimental because the shoe is meant for moderately technical trails anyway.

It will also help the shoe's outsole to last longer if you limit its use to trails and other off-road surfaces. Toothy lugs tend to erase faster when they are regularly exposed to concrete and asphalt.

We have nothing but praise for the Stiffness in cold 2's gripping capacity on moderate terrain.

Studded with 3.7 mm lugs, this Merrell shoe kept us surefooted when navigating loose rocks, climbing up and over downed mossy trees, and even trudging through some bog-like patches.

We should also note that the shoe's lugs were sufficiently spaced out to shed the mud and debris off while we were on the go.

There is a nice and large reflective element on the heel of the Merrell Stiffness in cold 2. Great for keeping you visible in low-light conditions.

Even though it is a lightweight shoe, the Stiffness in cold 2 doesn't skimp on padding. It offers a good 9.8 mm of foam in the tongue!

Breathable for summer.

The Stiffness in cold 2 comes with a semi-gusseted tongue which is very helpful for foot containment and tongue fixation.

But because the gussets come only halfway up in this Merrell shoe, they don't entirely protect the interiors from catching debris. Small branches, pebbles, and dirt still managed to find their way into our shoes.

Very thoughtful of Merrell to add two loops to the tongue and heel collar of the Stiffness in cold 2.

Merrell Moab 3!

The Merrell Stiffness in cold 2 features an ergonomically contoured shape which sat very well with our feet.

But if you find it uncomfortable or need to use your own orthotics instead, the shoe's stock insole is super easy to replace.

We are seeing more and more shoes from Merrell employ ethical materials and the Stiffness in cold 2 is one example. There are several sustainable parts in the shoe including:

• laces and webbing (100% recycled)
• mesh lining (100% recycled)
• mesh footbed cover (100% recycled)
• removable EVA foam footbed (50% recycled )

In addition to that, this Merrell shoe is also marked as vegan-friendly.