Research Notes: Xero Shoes Umara Z-Trail

Research Notes: Xero Shoes Umara Z-Trail

March 09, 2016 0 Comments

Research Notes is a series that reviews and recommends great footwear from a three-prong approach: style, biomechanics, and shoe construction. It also shines a light on how our own products change as we learn from our peers. 

First up is the Xero Shoes Umara Z-Trail. Founder Steven Sashen provided a pair for my review.

If I had to use one word to describe the Z-Trail, it would be Stability.

That is a big word to give to a running sandal!

The Z-Trail successfully addresses ALL of the drawbacks I found in huaraches I tried before. It also has a ton of other useful features. 

--Get Yours on


Early Huaraches

Back when I was running a lot more, huarache running sandals were my go-to. I liked running barefoot most, and thin sole sandals are as bare as it gets! Even more bare than Vibram FiveFingers.

In 2010, I got my first pair from Barefoot Ted's LUNA Sandals. These were a 4mm Vibram Cherry flat outsole sheet with hemp laces that you cut, punch, and lace up yourself. They recommended a toe post design, inspired by what the Tarahumara Indians used. These had some drawbacks, though.

#1 Having to make them. I had fun making my sandals, and even more fun customizing them. But then again, I'm the kind of guy who starts shoe companies. Most people aren't used to "some assembly required" for their shoes.

#2 Instability. These were pretty good on roads, but not so good on trails, for a few reasons. First, the toe post design has only ONE point and ONE line of stability for the forefoot, which is not much at all. Second, the round laces allowed the sandal to roll laterally. Third, the hemp laces, and most round laces I've used, would stretch when wet. 

#3 The slapping sound. One of the coolest parts about barefoot running is how silent you are. I have so much fun pretending I'm a hunter-gatherer, or a ninja. These early huaraches were pretty noisy, though, due to the instability mentioned in #2, and the flatness of the sole.

We will be revisiting these 3 drawbacks, and how future iterations addressed them.

I was able to make these early huaraches work better using my design below. The laces would wrap over and under your toes, so you have THREE points and THREE lines of stability for the forefoot. It was also easy to get in and out of, and adjusting the tightness was very similar to how we usually tie our shoes.

In 2012, I got a pair of Xero Shoes 4mm Connect. 

#1. Having to make them. You still had to punch holes in the toe area, lace them up, and trim the sole. However, they came with ready-made holes under the ankles, and the sole was relatively foot-shaped so it was easier to trim.

#2. Instability. Still the same. I stupidly wore these for Spartan Races not once, but TWICE. As soon as mud gets between your foot and the sandal, you start slipping like crazy. I ended up doing the majority of both these races barefoot.

#3 The slapping sound. This got better due to the slight toe spring that was built into the sole, but still more than I'd like.


Ready-To-Wear Huaraches

My first pair of Ready-To-Wear Huaraches were the LUNA Equus. My second pair of Ready-To-Wear Huaraches were the Xero Shoes Amuri Cloud. For some reason, I could not get the fit correctly on either of them. The heel straps would not stay up.

I kind of gave up on Ready-To-Wear huaraches at this point, and went back to the Xero Shoes 4mm Connect whenever I needed running sandals. 


Xero Shoes Umara Z-Trail

How well does the Z-Trail address the 3 major drawbacks of early huaraches? Very well.

#1 Having to make them. There was NO assembly required for the Z-Trail. The 3 front straps (the "Z") were easy to adjust AND stayed in place very well. The velcro heel strap was the same. No trimming of the sole required.

#2 Instability. These are the most stable huaraches I have ever worn. The first reason for this is that the front straps wrap around your entire foot at the balls of the feet. This is the widest and the flattest part of our feet, thus providing the most lateral stability. Second, the "Z" pattern provides lots of well-distributed points and lines of stability. Third, the flat strap doesn't roll around like round rope does. And fourth the straps don't stretch as much as rope. These sandals are REALLY stable. I can sprint and cut very reliably in these.

#3 The slapping sound. These are pretty quiet! There is a slight toe spring to the Z-Trail, so the sole lands under your feet, and not before your feet. The straps keep the sandal close to your feet during the entire stride.  

--Get Yours on

Here are some more things I like about it:

+ They use a 3-layer sole: a hard-wearing FeelTrue Rubber outsole, a durable TrailFoam midsole, and a comfortable-on-skin BareFoam insole. While it's nice to know that you can use just a single layer of material under your foot to run in, having different layers gives you a non-slip, durable, and comfortable experience underfoot. We do the same with our shoes and boots: a hard-wearing polyurethane outsole, durable cork midsole, and a comfortable-on-skin leather with a bit of Poron under it.

+ They're flexible! Because the outsole is only at the foot's major contact points, and not at the flex points, the whole sandal is more flexible.

+ They have an innovative outsole lug design! The arrows in the front point forward, and the arrows in the back point back, to give you traction where you need it when you go uphill and downhill.

+ They're light! 20% lighter than their Amuri Z-Trek, which is already pretty light!

+ They float! 

+ They come in an all-black colorway! Like I said, I'm a ninja =)

The one thing I did not like was this:

- They don't have enough room for my toes. I had to size up to 8, and you can see I'm still spilling over the sides a bit. However, I know that they will fit most people well. Xero Shoes has made a lot of custom huaraches for their customers over the years. They've seen a lot of foot tracings, so they know how actual human feet are shaped.


If I had to use one word to describe the Z-Trail, it would be Stability.

That is a big word to give to a running sandal!

The Z-Trail successfully addresses ALL of the drawbacks I found in huaraches I tried before. It also has a ton of other useful features. 

--Get Yours on

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V. HIRING: Outlet Store Manager
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Sneak Peek: Dress Boot Prototype 02
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Read my notes, and see more photos of the boots, both fresh out the box and ninja-footing through the mud.
Sizing, Fit, & Feel

I. Sizing

  1. Let's start by asking: What shoe size (US Men's) normally fits you best? To convert from other sizing standards, see this chart.
  2. Is that a Narrow width? Go one size down for our shoes.
  3. Is that a Medium width? Depending on how roomy you like the toebox, go one size down OR order the same size.
  4. Is that a Wide width? Order the same size for our shoes.
  5. Don’t know the width of your shoes? They’re most likely Medium. 

II. Fit & Feel

This image shows roughly how/where your feet should sit inside Chronology, at right. 

At left is a typical dress shoe, same size and same Wide width. You can see that it is still 1 or 2 cm longer than ours. Most sleeker dress shoes have a fair amount of unoccupied space in the front. We took advantage of that and used it to give you a wide toebox without looking like it. Dress shoes get even longer if we start looking at chisel-toe and pointy-toe styles. But even though these conventional dress shoes are longer, you still feel cramped because of the heel lift and the fact that their shoes are widest at the ball of the foot. Ours are widest at the toes, as a foot naturally is.

If the widest part of your feet (i.e. your toes) occupies the widest part of our shoes, then you are wearing the right size.

Regarding groundfeel, Chronology's outsole is 4mm thick, with another 4mm of leather and cork between that and your feet. The polyurethane we use for the outsole was selected for durability, which is more important than groundfeel in a shoe like this. The 2-part (polyurethane + leather/cork) design allows for the shoes to be resoled like good dress shoes and unlike most minimalist shoes.

Expect Chronology to feel less like FiveFingers and more like flat-bottomed skate shoes with the insoles removed.

In the end, what matters most is that you are happy with your shoes! We will gladly take them back (365-day free returns and exchanges, click for details) and I am honored that you gave us a shot.