New Balance Fresh Foam X Hierro v8 review

We're convinced that the New Balance Fresh Foam X Hierro v8 is an excellent pick for:

• Comfort-seekers who value a plush midsole above all in a trail shoe.
• New trail runners looking for a rookie-approved first shoe to start their adventures.
• Hierro series enthusiasts eager to upgrade to the latest model for its familiar flexibility and versatility.

We're convinced the New Balance Fresh Foam X Hierro v8 isn't the best option for everyone, particularly those seeking a lightweight trail shoe. Despite its continuous improvements, it remains heavier compared to rivals like the Hoka Challenger 7 or the Saucony Peregrine 14, both of which weigh in under 10 ounces.

Additionally, while the Hierro v8's plush midsole offers undeniable comfort, it lacks the responsive feel that many trail runners prefer for faster, proprioceptive trail running. For those looking for a balance between plush foam and responsiveness, we recommend considering the Nike Wildhorse 8, or opting for the Merrell Nova 3 for a more balanced approach.

While the Hierro v8's 32.2 mm heel stack doesn't place it in the maximalist category like the Brooks Caldera 7, it still offers a substantial amount of foam under the rearfoot.

This makes the Hierro v8 an excellent choice for multi-hour training seasons and even ultras.

The absence of a rock plate emphasises the need for substantial rubber and foam underfoot. Although 24.1 mm might not seem like a lot, the thicker-than-average Vibram rubber compensates for this, making the lack of a rock plate acceptable in our view in terms of protection, especially because this shoe is not meant for hard, difficult trails at all.

We also believe that this thickness particularly suits the shoe's goal of maintaining flexibility and its beginner-friendly approach.

The Hierro series has traditionally featured an 8-mm drop, and despite New Balance's claims that the Hierro v8 has a reduced 6-mm offset, our precise measurements—aligned with World Athletics guidelines—revealed an 8.1-mm drop.

Plus, on our feet, it delivered the same running experience as previous models.

This isn't the first New Balance shoe with Fresh Foam X that we've analysed in the lab, the velvet-soft 1080 v13 being another recent example. But we initially thought that New Balance might have adjusted the foam's formulation to make it firmer for trail conditions.

However, our Shore A durometer reading of 9.1 HA confirmed that it remains incredibly plush compared to most other trail shoes.

However, there's a caveat. While the EVA foam itself is exceptionally soft, it is sandwiched by a firmer-than-usual insole and a thick outsole. This combination creates a firmer-than-expected overall feel, making the midsole less soft than equivalent plush road shoes.

Additionally, don't expect significant energy return. Fresh Foam X, while being New Balance's premier training foam, prioritises comfort over bounce.

After chilling the Fresh Foam X midsole in our freezer for 20 minutes, its softness was reduced by 30.6% (12.0 HA)—a decent performance, though there is still potential for enhancement.

The insole is crafted from recycled materials—hence its unique mix of colors—and measures 5.0 mm in thickness.

The latest trend in running shoes leans towards creating rockered silhouettes, and the Hierro v8 kinda embraced it. Our comparisons show that the toe spring in the Hierro v8 is more pronounced than in its predecessor, though it still maintains a more level design compared to other New Balance road shoes such as the Rebel v4.

While we've established that the midsole isn't particularly wide, our curiosity led us to measure the toebox. Our digital callipers showed a width of 97.9 mm at its broadest point.

We're confident that this dimension comfortably accommodates the needs of about 80% of runners, providing a good fit for most feet. Additionally, it’s important to highlight that New Balance makes this model available in a wide option in some markets (including the US) which a nice bonus.

Our second measurement, taken in the big toe area, confirmed the toebox's average dimensions at 78.6 mm. However, it's slightly narrower by 1.9 mm compared to the Hierro v7, meaning runners with square-shaped feet might find the previous model a better fit.

Those seeking stability in a trail shoe might want to bypass the Hierro v8 despite its gigantic midsole sidewalls. However, neutral runners will find it performs well on easy trails and gravel roads without any issues.

For New Balance aficionados with stability concerns, the Fresh Foam X More Trail v3 is a better pick with its broader sole.

As mentioned earlier in this lab review, New Balance prioritises comfort in the Hierro v8, which is evident from the shoe's low torsional rigidity we observed during bending and twisting tests.

In our lab assessment, this feature scores just a 2/5, indicating limited rigidity.

To boost stability, New Balance has robustly reinforced the heel counter, crafting it to resemble that of a road daily trainer. We rated this strategic enhancement a solid 3/5, as it fortifies stability effectively without making the heel too stiff.

Upon examining the midsole dimensions, we observed that New Balance has preserved the streamlined silhouette of this series at just 113.2 mm.

We endorse this strategy—while other brands are excessively broadening soles to boost stability, New Balance focuses on maintaining agility and hiking performance in the Hierro, staying away from an oversized design.

The heel mirrors the design of the forefoot, offering a width of 91.9 mm—again around the average and well-suited for multiple activities.

From the outset, the Hierro v8 won us over with its exceptional flexibility. New Balance has engineered this by incorporating multiple holes in the Vibram Megagrip outsole, enhancing the shoe's ability to flex in every direction—evidenced by a mere 14.9N in our 90-degree flexibility test.

While many modern trail shoes opt for increased stiffness to boost stability, the Hierro v8 stands out as a flexible yet cushioned trail shoe. We're happy to see it offer an alternative in a market trending towards rigidity, filling a much-needed gap for those who value comfort over everything else.

In the second freezer test, we examined how the stiffness of the shoe altered after being frozen. Remarkably, the stiffness only increased by 17.6%, which is excellent news! This minimal change underscores the Hierro's consistent feel, even under extreme cold conditions.

Upon examining the midsole dimensions, we observed that New Balance has preserved the streamlined silhouette of this series at just 113.2 mm.

We endorse this strategy—while other brands are excessively broadening soles to boost stability, New Balance focuses on maintaining agility and hiking performance in the Hierro, staying away from an oversized design.

We just discussed the need for trimming weight, especially since the Hierro tipped our digital scale at 10.5 oz or 298g.

This is notably heavier compared to other trail shoes. New Balance would do well to reduce the Hierro's weight to below the 10 oz mark, which would significantly enhance its appeal for those who favour lightweight trail shoes.

While trail shoes generally require less ventilation than road kicks, the Hierro disappointingly scored a 2/5 in our smoke-pumping test, making it suboptimal for hot summer activities.

Using our light test, we found that New Balance reinforced the upper everywhere but the toebox. However, despite apparent ventilation holes in that area, smoke remained trapped inside during our tests.

To solve this mystery, we moved the Hierro v8 to our microscope examination area.

It became clear that while the engineered mesh is of good quality, it doesn't effectively ventilate because it features a dual-layer design with the bottom layer trapping heat—great for winter but problematic for summer.

We also noted the upper's fantastic comfort. It's evident that weight was not a primary concern in its design at New Balance HQ, as the material felt quite plush and heavy when compared to other models.

The New Balance Fresh Foam X Hierro v8 boasts substantial protection in the toecap—dubbed Toe Protect—and throughout many other parts of the shoe. But the toebox itself felt fragile to us, prompting us to put it to the test with our Dremel.

What we discovered was deeply disappointing, leading us to assign it a dismal 1/5 rating. While this issue might seem minor since it affects only a small part of the upper, it's worth noting for those who have experienced wear in this area with previous models.

Interestingly, the Hierro might not quite live up to its name, which means "iron" in Spanish. However, this isn't a reference to the material but rather a nod to the rugged and beautiful terrain of El Hierro in Spain’s Canary Islands.

After a disappointing first Dremel test, we shifted our focus to the Hierro's heel, hoping for better results.

Unfortunately, our hopes were only partially met, as the heel showed a slight improvement but still earned a lacklustre rating of 2/5. This was yet another letdown in our series of Dremel tests.

Following two previous disappointments, we turned our attention to the Hierro's outsole, which held potential as a standout feature again, as it's supplied by the Italian industry leader, Vibram.

Our initial evaluation of the Vibram Megagrip outsole involved measuring its hardness, which registered at 81.5 HC—a very balanced approach. We're eager to see how it performs in our upcoming Dremel test.

Until now, it seemed that the Dremel tests and the Hierro weren't a great match, but that finally changed.

We revved up the Dremel one last time at 10K RPM and discovered that the Megagrip compound performed exceptionally well, showcasing a remarkable blend of grip and durability. The minor 0.7-mm indentation we observed truly impressed us, leaving us quite satisfied with this result.

We also measured the thickness of the outsole using our vernier callipers, which registered at 3.0 mm.

This is relatively thick and, considering the excellent durability of the rubber, it's possibly more than necessary. This likely represents a missed opportunity to reduce the overall weight of the shoe.

In line with its design focused on versatility, the lugs on this shoe measure 4.0 mm deep—ideal for tackling easy challenging terrain effortlessly.

Of course, it's evident that these lugs aren't suited for more demanding terrains, so it's best to steer clear of muddy or slippery conditions or exhilarating downhills. However, they excel on simpler trails, a performance that's we found it's enhanced by Vibram's Traction Lug technology.

A proper trail running shoe should include reflective features, yet the Hierro v8 fails to include them. While not a deal breaker, we are quite disappointed with this oversight.

The only upside to the tongue is that it includes 6.6 mm of padding, which provides adequate comfort in the instep area.

However, our disappointment deepened when we discovered that, not only is the tongue non-gusseted, but it is also completely detached, lacking any integration with the lacing system—a standard feature in almost any other running shoe.

One crucial feature of a proper trail shoe is a tongue that is fixed to the sides, which provides two significant benefits: enhanced lockdown and better protection against debris entering the shoe.

Regrettably, New Balance opted for a non-gusseted tongue in their latest Hierro, a choice we found quite disappointing here in the lab, especially because this is not a cheap shoe at all. This omission compromises both the fit and the shoe’s ability to keep out small debris.

The heel includes a convenient finger-loop heel tab, a useful feature retained from its predecessor, thankfully avoiding any downgrade in this aspect.

We appreciated that the insole of the Hierro v8 is crafted from recycled materials, although this does result in a firmer feel than usual. Fortunately, if you prefer a softer footbed, you can easily remove the original and swap it with one that better suits your comfort preferences.