Do you remember running barefoot across a grassy yard during the summers as a kid? The freedom you felt, the joy, the strength? Many of us have been trying to recapture that feeling ever since. And most running shoes today don’t even come close to it, fancy gels, air pockets and cushioned soles not withstanding. Several manufacturers have offered solutions in the minimalist, or barefoot, shoe market.

Xero’s TerraFlex show is a high performance, minimalist trail runner. It is super lightweight with aggressive tread and one of the most comfortable running shoes I have ever worn. This is not my first foray in to minimalist shoes, but it is my favorite.

What are minimalist shoes?

So what is a barefoot, or minimalist shoe? Many argue about that but at its core, a minimalist shoe mimics the natural shape of the foot, allowing it flex and move as it was designed to. They also provide a closer sensory connection to the ground.  Your foot can feel the terrain while still having enough sole to protect it from what may be on the ground.

Why minimalist shoes?

Better connection between the runner and the ground, enabling a more natural running stride and strengthening the muscles in the foot that oft go unutilized in traditional running shoes with thick soles and various cushioning systems. The goal was to take runners back to a running style closer to the barefoot running we were built to do. Minimalist running hit the mainstream a decade ago, and many runners jumped in to it too fast, leading to injuries and pain. Barefoot, or minimalist running, still works for many though, especially when alternated with running in more traditional running shoes. In order to minimize injury, easing in to minimalist running is best, starting with very low mileage to get your feet used to the close ground connection and your body used to the running stance. 

From the manufacturer:

We make Xero Shoes differently. We make Xero Shoes for feet. Your feet.

To do this, all our sandals and shoes are grounded in the “3 pillars of Natural”:

      1.Natural FIT — Our sandals and shoes have wide toe boxes to let your feet spread out naturally. They have non-elevated “zero-drop” soles for proper posture.

      2.Natural Flexibility and Function — Our exclusive FeelTrue and FeelLite soles let your feet bend, and flex the way they’re supposed to, for balance and agility.

      3.Natural Feel — There are more nerve endings on the bottom of your feet than anywhere but your finger tips and lips. Your feet are supposed to FEEL the World. Our footwear lets you do that, with a Goldilocks “just-right” layer of protection.


Xero stands for zero drop. It is a true minimalist shoe. It roots are clearly in Xero’s best selling Prio, but designed for runners who spend more time on the trails and thus need more traction.

Most trail running shoes I have bought have been heavier than my regular running shoes. These go the opposite direction. At 9.6 ounces ( men’s size 9), they are only two and a half ounces heavier than some XC racing flats.



The shoes have a very short break in period. They felt like they were made for my feet. The wide toe box gives your fore foot a natural freedom of movement and flexibility. Your foot can move like it was made too. The snug heel cup and instep though keep your foot from slipping and sliding (where I normal have the most movement in my running shoes). No socks are needed either with this shoe, and breathability is excellent.



The huarache style strap is integrated in to the lacing system and can tighten across the instep and the heel cup if needed. It was already a perfect fit in my case.


An aggressive tread (but not overly so) and grippy outsole give this shoe what it needs to take on the woods, fields and trails. Like the Prio, the Terraflec has a FeelTrue® rubber sole. With the 4mm lugs and 6.5mm sole thickness (including the 3mm embedded BareFoam™) you end up with an 11mm total stack height, slightly thicker than the Prio but not noticeably so since with the lugs it isn’t solid rubber across the sole. There also is a removable 2mm sock liner and while on the subject, no socks are needed with the shoes.

A neat feature with Zero is their 5,000-mile sole warranty — Like all their FeelTrue® soles, the TerraFlex is backed by a 5,000-mile sole warranty. If you wear your FeelTrue® outsoles (or FeelTrue® section of Z-Trail) down to less than 1mm thick at the ball or heel of the foot (not an edge), we’ll replace them with the same product for the following price: 60% off MSRP (full, non-sale, listed, retail price) for the product, plus shipping.


Not many frankly. Some complain about the laces being too fat/thick. Not an issue for me but…

There really is no ankle/arch support, so that may be an issue to consider depending on the terrain you run on. I definitely felt every root and rock, and so learned to pick my foot placement differently very quickly. Lastly, Xero went through a period having sizing issues with the Terraflex. It seems to be fixed now, but may have lingering confusion in the marketplace. I noticed on my pair, my toes touched the end of the shoes. The owner assured me that due to the Terraflex flexing very differently than a traditional running shoe, my toes touching should not be an issue. And sure enough, he was right. I was afraid my toes would get beat up hitting the end of the shoe. In reality I never noticed it, during or after a run. If you are worried though, move up a half size, and you’ll be good to go.

I’ll end with this story. I was at a church event and saw a 9-year-old boy, full of the energy so common to young boys. He was wearing a pair of Xero shoes as well so I went up and showed him mine. We bonded over our cool shoes and his mom approached to share her experience with the shoes. Her son, Phoenix, has autism and has for most of his life refused to wear shoes of any sort. Until they found Xero. The fitted heel and wide-open toe box provide the only fit that in his sensory overload, he can handle having on his fit. To this mother, living in Northern New England with a very active 9-year-old son with autism, these shoes have changed this family’s life. To Phoenix, they were simply “Thumbs up, 100%!”


If you are an active runner interested in the minimalist shoe movement, and if you don’t want fabric between your toes like some of the other alternatives out there, you should definitely consider Xero. And with their warranty, you’ll likely have these shoes for a long time.

Material Disclosure

I received this product as a courtesy from the manufacturer via Spotter Up so I could test it and give my honest feedback. I am not bound by any written, verbal, or implied contract to give this product a good review. All opinions are my own and are based off my personal experience with the product.

I received this product as a courtesy from the manufacturer via Spotter Up so I could test it and give my honest feedback. I am not bound by any written, verbal, or implied contract to give this product a good review. All opinions are my own and are based off my personal experience with the product. No commission was received for this review, although we are bound by Xero’s updated Terms and Conditions to disclose that we could for reviews.

By DougP

Doug is a former CIA officer with extensive overseas experience in Asia, Europe, Latin America and the Middle East. He has an MBA from Wharton and worked in high tech, private equity and manufacturing. He regularly writes on business and intelligence topics for both web and print publications and advises on film and TV productions

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