Things Fall Apart

Since my previous post demonstrated – quite forcefully, as it happened – one of the drawbacks of minimalist footwear, this seems like a good time to throw together a collection of photos that address some other shortcomings of my most heavily-used trail runners over the past several weeks.

Mainly, the issue is one of durability, and each of my favorite brands – VivoBarefoot, Soft Star, and Vibram – have demonstrated some limitations in this regard. Before we get to the specifics, a few general observations are worth mentioning:

1) Durability seems to be an issue of high importance for minimalist runners, although I tend to think it’s a little bit overemphasized. The thinking goes like this: since true minimalist footwear doesn’t have a midsole, the conventional recommendation of changing shoes every 400-500 miles – a guideline perpetuated by traditional shoe manufacturers, and ostensibly based on midsole life – doesn’t apply to minimalist footwear. Therefore, the only things that prevent you from running 1000 or 2000 miles on your minimalist shoes are the outsole durability and structural integrity of the upper.

However, even though this is a post about problems with shoe durability, keep in mind that I’ve put a minimum of 400 miles on each of these pairs, which represents a typical running shoe lifespan, and would ordinarily justify the purchase price. But for whatever reason, for better or worse, the yardstick for minimalist stuff is different.

2) I think it’s fair to say that I’m pretty brutal on my shoes, and put them through some extremes that a lot of other runners might not encounter. I test everything on trails, whether they’re intended for trails or not. I go through river crossings, dense brush, bushwhacking off trail (sometimes intentionally, other times not) and routinely do very steep climbs and descents on virtually all kinds of terrain. And with increasing frequency, I’m using these minimalist models for my ultra training and racing. So in medical parlance, I do a lot of “off-label” use that might not be a factor if you’re merely looking for something to run around the neighborhood in.

The secondary benefit – besides all the fun of the actual testing, that is – is that weaknesses in the construction of these shoes become apparent a little earlier in the lifespan with hardcore use – and that brings us to the photos:

Exhibit A: VivoBarefoot Evo

These are my VivoBarefoot Evos with approximately 425 miles on them:

Of all my minimalist shoes, these have the best overall fit, they’re extremely comfortable, and they’ve performed much better than expected on rugged trails even though they’re not intended as an off-road shoe. I wore them for my (unfortunately, ill-fated) 100K last month, and the only performance issue I’ve ever had with them is diminished traction on loosely packed downslopes. The structural problem here is with the uppers:

As you can see, the mesh and TPU upper have begun to split apart - and this wasn’t due to a fall or unusual trauma, as both the left and right shoes show the exact same wear in the exact same location.

My VB contact person informed me that a similar problem had been reported by a couple other high-mileage runners. Apparently with a narrower than usual (by VB standards) last shape, the impact and flex points cause too much pressure on that particular region of the upper, causing it to split. These incidents all occurred with the very first production run, and VivoBarefoot’s technicians and design team have already addressed the problem for the 2nd production run which is currently sold in stores and on the website.

To give you a sense of scale, the mesh on the first production was tested to 20,000 "flexes", and the newer production runs are tested to 300,000 - in other words, you'd have to log 15 times more mileage to reproduce this same failure on the current version. What's more, the rep told me that VivoBarefoot is currently testing an even more durable material for the Evo models that will be launched in the fall; needless to say, I’ll be very eager to put them through the paces.


Exhibit B: Soft Star RunAmoc

These are my Soft Star RunAmocs with about 550 miles on them:

My love affair with the RunAmoc is well documented; from contributing to the design process to campaigning for the name selection to wearing them for my first 50-miler of the year this spring, they’ve been nothing short of a delight to wear from the moment the sizing and material selections were dialed in.

The fit of these is much looser in the rearfoot than the Evo, and since I tend to land on the inside of my heels – especially on the right – the wear pattern on the outsole is abnormally heavy on the inner section:

Traction on the outsole has worn down enough that I have some minor slipping on loose terrain, but that’s not the point of breakdown here. Rather, since my heel impact area drifts so far inward, I actually land upon the inner portion of the perforated leather upper – and I’ve done this so much that I’ve worn a hole in the leather:

My Soft Star contact said she is pretty sure they will be switching to exclusively suede backs instead of perforated leather on the next version of the RunAmoc, because it is a more durable material, and it also "stands up" and holds its shape better to keep the foot more centered. Since my pair was a hybrid (one perforated leather heel, one suede heel), I can attest that the suede heel style does indeed hold up much better; my only concern will be how well it dries after getting soaked in wet grass or stream crossings.

If the heel is switched to suede, I’d like to see the forefoot upper remain perforated, both for the ventilation benefit and for faster drying. In the meantime, I’m still logging mileage in my current pair, because I truly love using them, and because I’m curious as to just how far I can run in them before they completely fall apart.


Exhibit C: Vibram FiveFingers KSO

Here is one of my FiveFingers KSOs after nearly 750 miles:

The KSOs were one of my first pairs of minimalist footwear, and this pair has more mileage on them than any shoes I’ve ever owned. The outsole is holding up fantastically, but as you can see I have a little “situation” with the heel strap – namely, it tore in half about 4 weeks ago. Normally the end of the strap threads through the horizontal eyelet, and the top portion folds through it before doubling back on itself with a Velcro attachment.

I’ve still been running in these, with a makeshift adaptation:

Now I thread the top strap directly through the eyelet, and there’s barely enough length to fold it back to fasten on top. The heel isn’t quite as secure as it was before, but it still manages to stay on my foot fairly well. I also make one more adjustment:

Since I haven’t brought myself to officially cut the torn strap off yet, I just wrap it around its remaining portion and go on my way.

As far as the upper is concerned, I’ve experienced another structural issue that’s not unusual with FiveFingers users:

Separation along the seam of the big toe, which is more likely to happen if you pull directly on the toe when removing the shoe. I quickly learned to take off my FiveFingers by grasping the underside and pushing it forward off my foot, but by that time the damage was already done.

Obviously, neither of these problems has prevented me from racking up mileage on the KSOs, and I haven’t experienced either of these issues with the KSO Trek. However, I’m definitely more attentive to the Treks, making sure to rinse the uppers after every few runs – I suspect that salt buildup might have contributed to brittleness of the KSO strap – and removing them properly each time.

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Even with all of the above developments, I’m very satisfied with the performance of each of these minimalist options, and none of the issues I’ve described is enough for me to stop using those particular brands. Rather, I believe that as these products become more prevalent and more rigorously tested by various users, the companies will identify points of weakness so they can tweak future models for improved performance. Vibram is famous for incorporating user feedback into new models, and it appears that VivoBarefoot and Soft Star are proving themselves to be just as responsive.

Each of these companies has demonstrated a commitment to developing high-performance minimalist footwear, and I look forward to seeing what changes and improvements they have in store in the future.