Our reviews

/100 by , posted on .

With an integrated sock, state of the art lacing system, and top-shelf outsole, the New Balance Fresh Foam Hierro Boa should be a tough performer. Hierro means “iron” in Spanish.

Are these as tough as iron? Let’s take a look.


The basics

Size and weight: Normally, I wear a US 11. This shoe runs pretty true to size. It may be just a bit on the smaller size than usual, so if you are on the border, go ½ size larger. I weighed these in at about 13.1 oz per shoe, for my size.

Visual: No doubt about it, these shoes look clunky. The thick, brightly colored sole against the darker top, add to the oversized look. The distance from the outside of the outsole to the top of the sock liner is just shy of 6”.



The lack of laces, being replaced by three “straps” across the top of the shoe, along with the Boa dials on the side of the shoe, add to the chunkier look of the shoe. The colors are not the worst, but unless they are the colors of your alma mater, you may be indifferent to them.

One of the cool design elements of this shoe is on the outsole. If you look at the red over the black on the outsole, it forms an arrow facing forward.



Stack and drop: The NB Fresh Foam Hierro has an advertised 8mm of drop. The stack is 30mm at the heel and 22mm at the toe.




Uppers: The uppers are constructed of a reinforced mesh. The base fabric is a woven breathable material and is infused and overlayed with reinforced multidirectional mesh.

There are no seams over on the front portion of the shoe. And, the only seams on the back portion of the shoe are those that reinforce the lacing system (more on that in a minute).

The toe has a flexible rubber cap that creates a reinforced Toe Protect cap.



Insole: New Balance uses a non-specific, insole. Nothing fancy, but it does the trick.



Midsole: The midsole is injected Ethylene-Vinyle Acetate (EVA) using New Balance’s proprietary Fresh Foam technology. This midsole compound is durable and reasonably long-lasting.



Fresh Foam is used across a range of New Balance shoes and delivers good rebound and minimal degradation over time. The exposed portion of the Fresh Foam EVA midsole has an abrasion-resistant texture which has held up well.

Outsole: The outsole of the FreshFoam Hierro Boa is a Vibram MegaGrip compound. Going back to 1937, Vibram has a long history of high-performance outsole compounds and designs.



The MegaGrip compound is formulated to maintain traction and grip, even on wet surfaces. There are lugs of varying depth in the design—with the deeper lugs being on the ball and heel portion of the outsole.



In addition to having a fairly deep design, the lugs form a pattern, which maximize grip in multiple trail conditions.



Boa Fit System: The Boa Fit System started in the Rocky Mountains of Colorado and has been around since 2001. It is used on ski boots, snowboard boots, cycling shoes, and medical bracing.

The Fresh Foam Hierro comes with a Boa Fit lacing system, instead of traditional shoelaces. There are three straps which cross the top of the shoe (think kids Velcro-type straps).



These straps have a cord which runs through the ends, and into a Boa dial. Push/snap the dial-in and turn clockwise, and the cords tighten. Pull/snap the dial out, and the cords loosen.

Liner: Instead of standard tongue in this shoe, there is a built-in bootie-type liner. This liner is a breathable, stretchable mesh. It is attached to the collar of the shoe and forms the tongue portion, which is fastened on the sides of the shoe, down by the insole.


At first, I was skeptical of the overall durability of these shoes. The mesh upper, sock liner, and plastic Boa dials did not conjure up images of bomb-proof longevity and durability.

That being said, I have been duly impressed with the toughness of this shoe. The uppers have held up well against the standard abrasions that one encounters on the trail. The plastic Boa dials have not had any issues, whatsoever.

My disclaimer is that I have not fallen or scraped the side of the shoe where it would have caused a potential problem.

However, I have been running in 10-40 degree weather, and the plastic has not appeared brittle, and the Boa fit system functioned flawlessly, even when covered in snow.

The stellar component on this shoe has to be the Vibram MegaGrip outsole. This outsole has shown hardly any wear; even after using it on snow, ice, concrete, single track, and gravel.



Maybe I am biased towards Vibram, but if I am, it is because I have had really good luck with the Vibram soles in the past. Kudos to New Balance for putting in an outsole on a show that is on the more expensive side: pay more, get more.

Comfort and fit

I have to admit that this is the first pair of shoes that I have run in, which have a built-in bootie liner. In the past, I have gravitated away from them for a few reasons.

First, I normally run in low cut socks, and I do not like anything coming above my ankle. This is a personal preference.

Second, I had it in my mind, that the built-in bootie liner would stretch out, and appear saggy, and not hold tightly around my ankle.

Third, I am not a huge fan of the way they look (again, this is a personal preference). After logging some miles in the Fresh Foam Hierro, I can say that most of my reservations have been dismissed.

I got used to the bootie above my ankle, and after a few runs in the snow, I began to appreciate it. The bootie did a great job of keeping the snow out, where I may have needed gators on a different pair of shoes.



Whatever New Balance did to keep the bootie stretchy, and maintain its shape, worked. They fit as tightly now, as when they were new.

As for the appearance, I am still not a huge fan, but this comes down to what you, as an individual like. If you are a fan of knit shoes like the Nike FlyKnit or some of the Adidas Ultraboost, then you will probably like these New Balance.

The overall comfort of this shoe is excellent. They took no time to break-in, and even after moderate distances, they generated no hot spots. The Fresh Foam midsole worked well in balancing the right amount of rebound with the right amount of cushion.


I would not describe this shoe as an all-day mountain running shoe, but by the same token, I would not hesitate to take these out for 3-4 hours on moderate terrain.

The lug design of the outsole and overall ergonomics of the shoe, seem to lend itself toward trails that are “flowier”. When I was on these types of trails, this shoe seems to float over the terrain.

I also think that this shoe handles admirably in loose conditions like sand and snow. I really think that this has to do with the Vibram MegaGrip compound, but I had a difficult time getting them to slip on ice (relatively speaking).

What I like

I appreciated the fact that these shoes were comfortable to wear from day one. If you try them on and get the sizing correct, you will not be disappointed with them.

In fact, after a few runs, you will probably like them more. As I mentioned before, I really like the Vibram outsole. This sole is tough, provides omnidirectional traction, and inspires confidence on a variety of terrain. What did I like the most?

The Boa Fit System

I was skeptical at first, but the Boa Fit System provides an infinite amount of adjustment. Start off with your shoe too loose? No problem. Take 5 seconds and turn the dial a couple of clicks.



Did you over tighten them, or are your feet swelling? Again, take 5 seconds, pop the dial out, push back in and tighten it to where you want it.

The other part of the Boa Fit System that I like is that it has the three, wide straps across the top of the foot. This means that there are not tight portions, as there can be with a traditional lacing system.

Not all feet are the same, and this Boa Fit System really allows for adjustments to the comfort of the wearer.

What I don’t like

My negative comments with this shoe are few. I am not a huge fan of the look. While if feels fast running, it looks somewhat slow.

The straps and Boa Fit System that I love for performance, also, detract from the overall appearance of the shoe.

Final review

  • Appearance 75/100
  • Materials 90/100
  • Longevity 90/100
  • Value for the Money 90/100
    OVERALL 86.25/100


The New Balance Fresh Foam Hierro Boa show is an edgier looking shoe that provides excellent comfort, grip, and adjustability.

Is this on the higher end of the price bracket? Perhaps, but you get what you pay for, and this shoe has a well-knitted, nice fitting upper, Boa Fit System, and Vibram outsole.

There are a lot of features built-in here. If you are after a shoe that you can grab and just enjoy the run with, then the Hierro is a solid choice.


| Level 2 expert Verified
Hi, I’m Tim and I’m a Colorado ultra trail runner. As a true weekend warrior, I spend much of my free time logging training miles and challenging myself to reach the next level. When I’m not running in the Pikes Peak region, I love spending time with my amazing wife and three awesome sons.

/100 by , posted on .

The New Balance Fresh Foam Hierro BOA is an exciting new shoe, packed full of features. It is a trail running shoe designed for steep rocky trails. I have logged over 50 miles in these shoes, and here are what I found out. 




At 12 oz, they are a bit heavier than other trail shoes, but they, by no means feel heavy in the hand or on your foot. It is also designed as a mid-foot strike shoe with lots of cushion.

Technical specifications

  • 8mm drop
  • 34 mm heel stack, 26mm forefoot
  • Neutral pronation
  • High arch


The Hierro BOA has a heavy-duty toe bumper, which I like, and a seemingly durable upper. It also has a built-in sock-like ankle gaiter. All these will protect your feet from rocks and debris.



BOA performance fit system

The New Balance Fresh Foam Hierro BOA feels a bit heavy. I assumed this was from the BOA system as I had never used this before, but that’s surprisingly minimalist and built from seemingly ultralight components. The weight mostly comes from the massive midsole.




The best part of this shoe is the BOA performance fit system. I only live about an hour from the BOA headquarters in Denver, so I went down there to learn more about this tech since I had never used it before. 






At first, I was skeptical of the lacing system. I am a convert though—this technology is fantastic. It’s not a lacing system—it’s so much more. I honestly think that this is better than the traditional lacing system.


The fit system really helps you dial in the performance of this shoe. There are two dials to adjust the fit over the top of your foot and through the arch, as well as one higher up for more heel/ankle fit.




The dials are simple to use: Push them down and turn them to adjust, and then just click them up, and they completely loosen. 

It was very hard to get into, I have a slightly wider foot, and it’s not an easy shoe to slip on by any means. I have had to run very thin socks to help with this problem, but once they are on, I don’t feel any hot spots or pinching. 




At first, they felt like my foot was sitting high in the shoe. I normally like a heel cup that really hugs the back of my foot, but after a few miles, I started to feel like they fit fine. 

There is an internal heel pad that does add some grip above your heel. If you prefer a deep shoe though, this one does feel a little lower volume, so it may take some getting used to. 




The Hierro BOA feels great on your foot. It has a thick cushioned EVA midsole perfect in protecting your feet from sharp rocks. It struggled to get a ton of trail feedback, but on sharp rocky trails of Colorado it saved my foot a few times for sure. 

Those looking at Hoka or Altra may want to consider these shoes as an alternative.


Grippy Vibram Megagrip outsole does the trick without it being obnoxiously over lugged. It is not as aggressive as I assumed it would be, but it grips, so it does the job. 




My one concern with the BOA system is what happens if it breaks of the lace is cut? BOA says they test these to the max for durability. I even got to see their testing lab, and it’s impressive. So, they assured me they are tough, but they can fix broken product as well if needed. 




My biggest issue with this shoe is it feels big to me. I don’t know if it’s the massive stack height, 34mm in the heel, or the 8mm drop that’s throwing me off, but I’ve tripped a handful of times on rocky trails. 

I’m more used to my Inov-8 TerraUltra, which is zero drop and only have a 9mm stack, so the extra 20mm of foam under foot could be the culprit. I’ll have to adjust my stride a bit as I continue running in these. 


After every time I wear the New Balance Fresh Foam Hierro BOA, I like them a little bit more. The cushioning is thick so my feet are less tired or sore at the end of a long run on rocky trails.

After a month of wearing them, the ankle gaiter are starting to break in a little bit, making it easier to wear over time. If you are looking for a pair of Hoka or maybe Altra, you might want to consider the NB Fresh Foam Hierro BOA.

These are pretty great shoes, and I am excited to run in them again.


  • Comfortable even for wide feet
  • Breaks in nicely
  • Easy to adjust lacing
  • Feet are less tired after runs


  • Difficult to get on and off
  • Feels a little bit unstable
  • Shallow heel cup
| Level 4 expert Verified
Over the past 20 years, Paul has climbed, hiked, and ran all over the world. He has summited peaks throughout the Americas, trekked through Africa, and tested his endurance in 24-hour trail races as well as 6 marathons. On average, he runs 30-50 miles a week in the foothills of Northern Colorado. His research is regularly cited in The New York Times, Washington Post, National Geographic, etc. On top of this, Paul is leading the running shoe lab where he cuts shoes apart and analyses every detail of the shoes that you might buy.

/100 by , posted on .

Out of the box, the New Balance Fresh Foam Hierro BOA has a striking first impression, with lots of notable features, but above all the BOA lacing system is a show stopper and one that is sure to put a stranglehold on the competition.

That alone makes this shoe worth talking about, but the super burly toe guard, the built-in ankle gaiter, the bombproof upper, Vibram Megagrip sole and Fresh Foam cushion combine to make this trail runner a force to be reckoned with.

There’s a lot to talk about so let’s get started!



Use: Trail
Drop: 8mm
Weight: 12oz


The New Balance Fresh Foam Hierro BOA has a stretchy upper bootie that integrates seamlessly into a more rigid upper material that ties into the BOA lacing system.

The snug bootie provides a comfortable and secure ride. I really liked the well thought out injection of lateral cushion found right above the heel box on the inside.



This helped create a nice, secure feel for the heel. The three more rigid flaps of fabric that synch down on the top of the foot provide a well balanced and equally distributed pressure on the foot, creating a solid fit.

The bootie of the upper shoe climbs the ankle a couple of inches to create a very functional and integrated debris gaiter. This hugs the ankle snuggly and is effective at both keeping snow and dirt out, as well as finalizing the overall comfort and secure fit of the shoe.

Ultimately, this is a superbly comfortable shoe that felt like home to my foot.



The BOA lacing system is by far the star of the show when it comes to the New Balance Fresh Foam Hierro BOA. The system utilizes three wide flaps of semi-rigid fabric that are controlled by two dials.

The micro-clicks of the dials allow the runner to fine tune the fit of the shoe down to the millimeter. An easy outward pull of the dial releases the system and a simple push back in re-engages it.

What I loved about this was that it gave me the ability to easily adjust my shoe fit on the fly. Rather than having to unlace a double-knotted lace, kneel down and try to adjust the lace throughout the network, two dial clicks and some micro-adjustments happen in seconds.



The Vibram MegGrip sole of the New Balance Fresh Foam Hierro BOA is another favorite feature of mine. An industry standard, Vibram has always been something I look for when shopping for trail running shoes.



The time I have spent in these shoes has been entirely on icy and slushy roads that lead me to snow-packed hiking trails.

Not once have I been wishing I had brought some sort of traction device with me. The grip of the New Balance Fresh Foam Hierro BOA is amazing.



The Fresh Foam technology is without a doubt notable. While you’re not going to get the “walking on clouds” feeling from these shoes, that’s not really what you want in a trail running shoe.

What you do want is enough cushion to keep your feet from being assaulted by every rock and root you encounter, but enough firm, responsiveness to provide a nimble footed agility on the ever-changing trail.

You want a shoe with enough cushioning to keep your feet comfortable for the long haul, but not so soft that it eats up your energy return. The New Balance Fresh Foam Hierro BOA does exactly that. I was impressed with its comfort and cushion yet with its ability to feel responsive and reactive.



The fit of the BOA lacing system was mentioned earlier but it also deserves a shout out in the performance department. The ease of adjustment is a godsend but the design of the straps that tighten over the bootie provided great foot security and really help with the overall stability of the shoe.

The ankle collar felt a little snug the first time I put these shoes on but when considering the dual function that it fulfills as a debris gaiter it makes sense. The gaiter did an excellent job of keeping out all manner of things and it’s worth the minor inconvenience of wrestling into the shoe.



The toe guard is nothing short of a beast. The toe’s hard double layer rubber beacons of a steel-toed boot but with none of the cold rigidity.

Its durability is certain to provide ample protection and stand the test of time. I suspect that the rest of the shoe will wear out far before the toe guard.



The tight weave of the upper material is impressive. The fabric is among the burliest I’ve seen and while it’s not waterproof, it has a water-repellent coating that helped keep me dry. I‘ve run mostly in cold wet, snowy conditions in this shoe and my feet have been kept reasonably dry and comfortable.



My feet did not overheat, but of course, it is cold right now and whether or not the Hierro BOA will run hot in the summer is something that I cannot really attest to. I hope they don’t because I really like this shoe.



  • Excellent lacing system
  • Well balanced cushioning
  • Integrated gaiter


  • Might run hot in the summer months


The New Balance Fresh Foam Hierro BOA has a lot going for it. If you’re searching for a trail runner that exceeds your expectations this is it.

The rugged, gripping Vibram sole, the beast of a toe guard, the water-resistant sheen, the snug bootie with an integrated gaiter and the comfort of the Fresh Foam cushion all add up to one heck of a shoe, but without a doubt, the BOA lacing system is the star of the Hierro.

At an MSRP of $160.00, it’s priced accordingly for all of the technical features you get.

| Level 4 expert Verified
My name is Sean Kiffe. I live with my wife and three daughters in Missoula, MT where I teach middle school science. I am primarily a trail runner but also dabble in road events occasionally. Currently, I am working my way into ultra distances and will be doing my first 50K and 100K trail races this season.

/100 by , posted on .

When I first opened the box, I didn't know what to think of these shoes. They looked to me like some kind of space boot, and also just... big.

I think the fact that it has a built-in gaiter PLUS the lace-less gears for tightening (the BOA fit technology) is what threw me for a loop initially. I have had several people comment on them in group trail runs ("What are those!" and "They look kind of wide")



Interestingly, they don't fit wide. They fit very average across my other brands of shoes.

I pulled them out of the box and was surprised at how light they felt!

They are 9.6 ounces per women's size 7 shoe, which is on the lower end of trail shoes of this genre. I was unable to find the details on the New Balance website for official weight, so I broke out my trusty scale.



I slipped them on and noticed how high the gaiter came up on my ankle. I wondered if this would be an issue for chafing. I then had no idea how to tighten them! But thankfully they came with instructions on how to operate.


First run

I decided to be cautious on the first run and aim for 3-4 miles. I wore socks that came up lower than ankle height because I wanted a thinner sock that day (I was a two weeks post breaking my right pinky toe).

This was a mistake but probably a good mistake because it showed me one of the limitations of this shoe.

I went out on the trail, hit some more technical rocky steep sections. They felt really stable! But around mile 2, I could tell that the skin above my heel on my Achilles tendon was getting irritated.



I ended up with a chaffed/bloody spot that is only now mostly healed (4 weeks later). So, these shoes require at least mini-crew height socks.

Over the next 50 miles…

I've used them for runs ranging from 4 to 12 miles, including a 12 miler where I PR'd (and CR'd) a bunch of Strava segments (so I was running kind of fast—they performed pretty well).

And, I went on another day of trail work out in Secret Canyon (in the mountains of the Cleveland National Forest, literally running with loppers and leather work gloves).

The lacing system performed really well in overgrown trail conditions. I never had to retie them, but others running buddies did because the brush would grab their laces and after a while, even double knots were coming undone.

Let's do a rundown on the components…

Lacing system

Overall, the BOA fit is pretty awesome. The only minor complaint I have is probably more with the shoe than the lacing system.

I found that during a run, I would feel like things had loosened a bit, and I needed to tighten them one more step. But, I had maxed out how far I could tighten: the little lacing strings were completely wound up.

And, that is probably because this shoe is designed for a higher foot volume (i.e. instep height) than what I have for feet.

But, the BOA fit performance in overgrown trail conditions was great. And, the ease of getting them loosened was just a couple quick pops of the gears and voila! They were loosened.


The outsole is Vibram, and I found it to be adequately grippy for the trails I ran. They performed reasonably well in muddier/wet conditions, though perhaps not as much traction as I would like.

The lugs are not large or aggressive. In attacking trail hills, at times, they felt a little like they lacked some oomph to grab.

The upside to this is they transition well to the road. I often run roads with my trail runs, particularly if I start from home (en route to the trailhead). I found them to be fast and smooth on the road.


Upper and overlays

Other than looking like a space boot, the overlays aren't obtrusive. The sock fit keeps the ankle locked in pretty well, and there is also a channel of padding that sits just above the back of the heel that worked very well.

I honestly didn't realize it was there until I started looking inside the shoe to write this review. Features that just work without noticing are, in my opinion, the best features.



The gaiter works very well to keep debris out, but as I noted earlier, I can only wear these with a mini crew and taller socks unless I want to have a bunch of hot spots on my ankles and Achilles.

I am not sure this flaw is really acceptable to me. I don't love when a shoe that dictates my sock choice to that level. I'd rather have my gaiters and be able to wear whatever socks I want (which is generally how I roll).

The ride

Stable, smooth, and fast. I found the transition from heel to toe very smooth. The heel to toe drop is 8mm, which, in my opinion, appeals to the masses. Right in the middle.


The colors are limited (as in currently only one colorway for the ladies), but appealing.

Price point

The price point is on the higher end at $159.99.


As for durability, it is really good as far as I can tell. I see very few signs of wear other than the dirt I accumulated from the trail. The lugs are all intact, nothing is ripping or stretched on the upper, and the midsole looks great as well.



The only flaw this shoe really has to me is the gaiter comes up too high and dictates my sock style. If you like a thinner sock, it is harder to find crew height socks that are thin. Those are usually reserved for no-show style.

If it were me designing updates, I would figure out how to make the gaiter shorter or not abrasive to the skin. I would also look into a little more leeway in the tightening of the BOA fit system.

It is otherwise a pretty innovative trail shoe. The price point is quite high, which is another area that would be a bit prohibitive to me.

But, it's super durable, so in that respect, it may be worth it for some folks. I have had some pairs of trail shoes that at 150 miles are falling apart.

I hope that future iterations of this will tweak some of the areas I mentioned. For the first release of a model, I am quite impressed. New Balance continues to deliver quality trail shoes and is one of my go-to brands for running in dirt.

| Level 2 expert Verified
My running obsession began in high school on the Cross Country team (and also Winter and Sprint Track) back in 1993! I've run over 20 road marathons, including four Boston Marathons (2020 will be my fifth consecutive). In 2019, I completed the Black Canyons 100K and PCT 50. Somehow, I also managed to win a few small trail races here in San Diego (Mt. Laguna Marathon and the San Diego Trail Marathon). Eventually, I would like to run the Western States (and maybe UTMB!).

/100 by , posted on .

The New Balance Fresh Foam Hierro BOA is an alternative version to the New Balance Fresh Foam Hierro but adapting the upper for the BOA Fit System.

This is the first time they have utilised a double BOA system on a trail running shoe giving users the chance to customize the fit.




Last year I used these shoes as part of a challenge to run across Iceland.

This meant running across the country from North to South, completing a total distance of 330 km in 9 days. I was running almost a marathon per day over the Icelandic terrain, which included crossing rivers on foot and traversing challenging volcanic ground.


The upper is constructed with synthetic mesh which the brand claims to be breathable but was in fact far from that. It is true that the sock-like fit removes the need for a traditional tongue, but this means that they have to add straps.

So in the end, the whole upper is covered in thick and not very flexible material. Debris-free, indeed, but it comes at a price.

The high cut is made in a more breathable material and is not too tight on the ankles. After more than 450 km it gets a bit loose but still does what it was meant to do.

The Toe Protector is quite solid and is good against rocks, roots and other obstacles it might come up along the way.



BOA fit System

The BOA System is the main feature of the shoes. It's part of the upper but these deserve a special mention. New Balance had previous versions of the Hierro without the BOA, but decided to release another version with it.

I consider myself a big fan of this system, and I use them on other running shoes, for both road and trail. But a double system? Is it necessary to put two dials on one shoe? Let’s see.

In my previous experiences with the BOA, such as the Adidas Agravic BOA, the tension you get with the wires is not easily evenly distributed and if you try to overtighten them you would feel pressure on the bridge of your foot.

To avoid this, New Balance created a road running shoe where they included these alternative straps, the New Balance 1500 T2.

These were designed to be quick to put on and take off in triathlons. I own to pair of these, and I love the BOA system in them.




Why is the BOA system important to me on trail running shoes?

Well, it is true I don’t need a quick way to take them on or off but I like to be able to adjust the tightness depending on the conditions.

I especially like my shoes really tight when going downhill, therefore having a quick way to set this up during my run is important. The tension and precision you can get with this system are usually impressive and the TX4 textile laces can take it.

So how did the BOA on the Hierro do?

I have some mixed feelings about it. The double straps/dials are a good concept and it worked. Being able to finely adjust the fit was good. Where did it fall short? The length of the single strap!

When I bought them and first tried them, they felt good. I pushed the dial to make it really tight… and it was fine. But after using it for a few miles when I wanted to make it tighter, the materials gave up a bit, and then I realised the issue.

The strap was limiting how much I could tighten it. I was turning the dial and suddenly it reached the strap and there was no more lace/wire.

The shoes weren’t loose, but I couldn’t get the extra tightness I wanted for certain points on the run. This could be a personal issue.

I have a normal ankle size, and this may not necessarily happen to everyone. But for me, it was a big issue for the downhills or technical terrains.




Another thing to consider about BOA dials and trail running is what happens if you hit them with a rock: can it get loose or even break?

I´ve never had this issue, but when running in long grass or bushes, some small branches have gotten stuck into it. These can just be removed and it´s fine.

After 300 km on the volcanic terrain, I noticed how some grit must have gone inside the dial and got a bit stuck when I tried to release it.

The good thing is that BOA offers a guarantee, and if you have any issue with the dials they will send you a spare kit to fix them for free.

Midsole and outsole

When you look at this New Balance shoe it is inevitable to see that the size of the midsole, is not as big as the Hokas, but is definitely bigger than other shoes.

The midsole is made with the Fresh Foam cushioning providing a cushioned and lightweight run. It has a nice equilibrium between a plush feeling and response.




The outsole is a Vibram MegaGrip sole. Vibram is one of the best when it comes to rubber material and you can feel it in these shoes.

It has a great grip on varied terrain and gives great performance on wet and dry surfaces. The lugs are not the deepest, making it ideal for non-technical terrain or compact gravel.




My main use for these shoes was on easy compact gravel terrain, and they felt really smooth. I didn’t have to worry about fatigue from the surface for many hours.




Despite the fact that this is not the lightest shoe, it didn’t feel too heavy at my moderate pace.

I have been using these for 20 to 45 km runs and they served me well. However, when I tried to use them on some downhills I missed having deeper lugs and a tighter fit.

The upper can be quite warm. This wasn’t the case for me in Iceland, where my feet were well protected from the cold temperature, but I wouldn’t recommend them for warm summer days.

Also, when they get wet they become heavy, and takes time for them to dry.


I was impressed with the durability of these shoes. Before my trip to Iceland, I used them for a couple of runs (20/30 km), and then I used them every day for 9 days…

In total, I ran 450 km with them and as you can see in the pictures there are barely any signs of wear. The Vibram Outsole is a good guarantee of high performance and durability. Taking a close up view, only the tip is slightly worn.




The elastic of the sock-like end, gave up a bit and is not as tight as it was when brand new, but is still good enough to keep debris out of the shoe.

As mentioned before, the BOA system got a bit stuck sometimes, but it may be that some dirt got inside the mechanism.

I still use them occasionally on a mix of road and gravel surfaces and the Fresh Foam midsole still feels as plush as the first day.




  • Comfy midsole with extra toe box space
  • BOA system easy to fit
  • Good grip on wet and non-technical terrain
  • Well protected against debris and stones


  • BOA System gave me a limited fit
  • Lugs not deep enough for more technical ground
  • Feels chunky and heavy
  • Not the most breathable shoes for the summer


These are great shoes. I used them for 450 km, but they´re not for every occasion or every runner. They´re cushioned and protected, but feel heavy and chunky therefore I wouldn’t use them in a race.

On non-technical terrain and at a steady pace they work great. The Fresh Foam midsole can absorb a lot, giving a comfortable and smooth ride.

The main feature and eye-catching is the BOA fit system, and I have some mixed feelings about this one, a nice idea but didn’t work for me in some situations.



| Level 2 expert Verified
Hello, I'm Ale - a road runner since 1997 and a passionate trail runner for the last 3 years. I'm part of a community run in London, Wild Trail Runners (powered by Salomon), and always happy to advise people about the different shoe options. Living in London, my weeks run are on the road and every weekend escape to the trails. Last year I took part in memorable trail races like MIUT, Eiger E35, Mont Blanc Marathon, Transgrancanaria, and ran across Iceland from North to South, 330 km in 9 days.

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The appearance of the Hierro Boa is certainly going to be a polarizing one for trail runners everywhere. Its very distinctive burrito wrap upper and BOA fit system make it stand out at first glance compared to the laced shoes that we are all accustomed to.

Personally, I am a fan of the appearance and particularly think the design team did a great job when selecting colorways, the pair I tested and shown below are the Neo Classic Blue with Varsity Gold & Black.

I always love having trail shoes that are bright colored rather than lighter weight and drab hiking shoes.


Tech specs

The Hierro Boa is a protective but neutral trail running shoe that will really excel with runners looking for a trail shoe more similar to road trainers. The sizing is fairly standard as you should be able to wear the same size you would in most running shoes.

These tip the scale at 11.4 oz (323g) in a Men’s 9 which makes them a little on the heavy side for if you are used to more minimal shoes but are generally in line with the expectation for a cushioned trail shoe.



With a heel-toe offset of 8mm, these should be good for both runners used to more minimal shoes looking for less strain on the lower leg and for those used to standard trainers wanting to explore the trails.

Personally, I prefer 4mm drop shoes but had no issues with adjusting to the higher drop on these.


Thus far, I have put about 100-mile mountain trails and fire roads on this pair and had no issues with premature wear. The Vibram Megagrip outsole is the gold standard for trail shoes and holds up to that reputation on these with no signs of wear yet.



Additionally, the upper bootie construction is very sturdy and durable, still looking the same as out of the box.

I anticipated these will easily last for several hundred more miles of rugged trail running with my only long-term concern being the BOA mechanism, however, that shoes be replaceable if it wears out before the rest of the shoe.


The upper is a bootie design made of mesh/synthetic materials that does a good job of keeping your feet dry and still pretty well ventilated.

One concern with the upper is the way you have to slide your foot through the sock-like collar to put the shoes on. Personally, I had no issues with this, but it does have a snug fit that could maybe be improved with additional elasticity.

That being said, I really enjoy the upper of these as they provide solid protection running through brush while avoiding becoming a sweat trap.



Another big plus of the collar being more snug is that it functions as a gaiter and does a phenomenal job of keeping debris from affecting you on your run.

The most notable part of the upper is, of course, the BOA Fit System. Basically, New Balance decided instead of laces to implement this dial system, which in theory would make it easier and faster to provide lockdown for the shoe.

I really liked this feature as it makes putting on and taking off the shoes nearly effortless while also eliminating the issue of laces coming undone or getting caught in brush as I have experienced quite often running trails.

One concern would be whether this would be able to provide a good lockdown as its laced counterpart. For me, these have provided a very secure and confidence-inspiring lockdown while saving time and looking pretty futuristic to those you pass by!

As for the comfort of the upper, I have not had any issues with hot spots, even running 14 miles in them out of the box.

Midsole & ride

New Balance decided to use its patented Fresh Foam midsole, which provides ample cushioning and protection, especially for a trail shoe that helps prevent your feet from getting as beat up and fatigued from rocky trails.

This, coupled with the moderately high drop and road trainer type midsole, gives it a smooth and forgiving ride. I personally find it ideal for Ultras or other long training runs on the trail along with even as a good hiking option.



One issue I did have with the ride was the stack height. While having a higher stack height helps to limit the discomfort of rocks and roots underfoot, its one big drawback for me when making sharp turns or shifting directions quickly as one does on steep downhills and technical trails.

This is a personal preference; however, I prefer a lower drop shoe for fast downhill running because it decreases the chance of rolling an ankle.

Overall though, the ride is great, and the midsole does its job. I see these as near perfect for fire road trails and other less technical trail Ultras or long runs.


The outsole of the Hierro is top of the line, which is to be expected with its utilization of the Vibram Megagrip technology.

I do think that they could reduce some of the shoe’s weight if they decided to not make this a full-length outsole. However, in its current state, it provides a smooth transition.



As for traction, the Hierro has plenty. I was pleasantly surprised since it doesn’t have an aggressive outsole pattern as a lot of trail shoes opt for, but it has handled everything very well, including mud, sand, and even snow.


New Balance has done a great job of making a trail shoe that will work amazingly for those adjusting from road running to trail by providing the protection they are used to with the traction and durability required.

The implementation of the BOA Fit System is a great step forward, and I hope to see this used with more shoes in the future both for the trail and road. I will continue to run long trail runs in these and use them for hiking when I don’t feel like tying my shoes.

The MSRP for $159.99, which is a bit on the high side, and why they received a low score for value.

However, as of right now, you can get them on New Balance’s website for 25% off, and I think that is a very fair price point for trail shoes that look great and should last for near 1000 miles for the more efficient runners.

| Level 1 expert Verified
Hi, I'm Drew and I've been running for 12 years now. I've run as high as 80+ miles per week, but tend to stay at 50 running and 20 hiking. I love trail running, but I run on roads and track as well! I run everything from 800m-mountain trail races.

Notable elements of the New Balance Fresh Foam Hierro BOA

- The New Balance Fresh Foam Hierro Boa is a highly durable trail running shoe that offers a balance of comfort, style, and performance. 

- This New Balance trail running shoe utilizes a TPU-coated textile coverage that offers breathable coverage. The upper also incorporates the Boa® Closure System that allows the user to dial in a customized fit. 

- Providing plush comfort is the Fresh Foam technology integrated into the midsole of the shoe. This foam material offers optimal cushioning even on aggressive trails. 

- To provide maximum grip, the Vibram® MegaGrip outsole technology is utilized in the shoe. This outsole material delivers great traction in both dry and wet conditions. 

Size and fit

The New Balance Fresh Foam Hierro Boa is constructed using the standard sizing measurement. Runners can get a pair in their usual sizing expectations. However, it is advisable to try on the shoe first or utilize the general feedback about sizing to ensure a comfortable fit. 

The technical part that affects the fit of the shoe is the Boa® Closure System, which allows for a customized fit.


This running shoe utilizes the Vibram® MegaGrip outsole for superior grip on both wet and dry surfaces. The Vibram® MegaGrip outsole is lightweight and water-resistant. It prevents the feet from getting damp and protects the shoe from becoming damaged so quickly. 

Other popular trail running shoes that feature the Vibram® MegaGrip outsole are the Altra Olympus 3.0 and Hoka One One Speedgoat 3.


Just like the New Balance Fresh Foam Hierro, the New Balance Fresh Foam Hierro Boa also incorporates the Fresh Foam midsole cushioning technology. This component is precision-engineered to provide an ultra-soft and lightweight ride. It is designed to give optimal comfort and support for long runs. 


The bootie upper construction is designed to provide a supportive fit, reducing in-shoe slippage. The bootie construction and no-sew material application lessen the shoe’s overall weight and prevent the risks of rubbing and blisters. 

The breathable and flexible TPU-coated textile upper aims to keep the foot dry and cool throughout the entire running duration. 

Incorporated into the upper is the Boa® Closure System for a customized fit without pressure points. The Boa® Closure System is used as an alternative to the traditional lacing system. It allows the user to easily adjust the tightness around the shoe. 

The shoe also uses the Toe Protect™ technology. This component protects the foot from rocks, debris, and other elements.


The current trend of New Balance Fresh Foam Hierro BOA.
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Jens Jakob Andersen
Jens Jakob Andersen

Jens Jakob is a fan of short distances with a 5K PR at 15:58 minutes. Based on 35 million race results, he's among the fastest 0.2% runners. Jens Jakob previously owned a running store, when he was also a competitive runner. His work is regularly featured in The New York Times, Washington Post, BBC and the likes as well as peer-reviewed journals. Finally, he has been a guest on +30 podcasts on running.