Our verdict

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 on my test runs, I discovered that this shoe has a well-knitted, nice-fitting upper, Boa Fit System, and Vibram outsole. There are a lot of features built-in here and I'm a big fan of all of them. If you are after a shoe that you can grab and just enjoy the run with, then the Hierro is a solid choice.


  • Durable
  • Grippy
  • Responsive
  • Nice fit
  • Durable upper
  • BOA lacing
  • Very comfy


  • Looks
  • Expensive
  • Slightly heavy

Audience verdict





New Balance Fresh Foam Hierro BOA review

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 coloured 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 colours are not the worst, but unless they are the colours 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.

Nice, breathable upper

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.


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

Durable 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.

Grippy, durable 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 maximise grip in multiple trail conditions.

Boa lacing 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.

Built-in bootie-type 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 sceptical 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).