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NNormal Shares a Look at the Durability of Its Kjerag Trail Running Shoe

NNormal shares results from a study on the durability of its Kjerag trail running shoe.

By on February 13, 2024 | Comments

In its two-year existence, the brand NNormal has put its values on the table. One of those core values is sustainability. In that vein, for one of the first times we can recall in the running industry, the company shared the results of an internal study of the probable lifespan of its shoe based on real-world testing.

The simple questions the study asks are: How many kilometers can a person expect NNormal shoes to last? And, as a result, how does that affect the environmental impact of one’s running shoes?

The brand’s assertion is that companies are too focused on the CO2 consumption of a shoe individually when it is actually the CO2 savings by simply consuming — thereby producing — fewer shoes that is more impactful. To this end, NNormal promised to keep impact minimization at the forefront and to make its goals and progress known along the way.

NNormal Kjerag durability test

NNormal’s photos showing the Kjerag during different mileposts of its durability test. Image courtesy of brand.

Like driving a Toyota Corolla for 300,000 miles, it might be a point of pride to see how many miles one can eke out of their running shoes before retiring them. For most of us, we simply want to get as much as we can out of a pair of shoes before performance or integrity is lost, especially when their cost is always rising. Additionally, as we develop a greater understanding of the environmental impact of our trail running hobby, many of us want to make our own running more sustainable.

In early February 2024, NNormal released a durability or lifespan study, the first formal internal review it has made public. The subject shoe was the brand’s debut, the Kjerag — see our NNormal Kjerag review — which founder Kilian Jornet famously raced an entire season in one pair, including wins at Zegama Marathon, the Hardrock 100, and UTMB.

Though its public report doesn’t currently reveal factors like whether the 511 testers were compensated or provided shoes for free — not to mention some intangibles like were they more likely to report positively/less negatively based on being a fan of the brand — the study says that the runners’ weight, the type of terrain they run, and certain points of emphasis along a durability scale were all included.

The durability scale in the image above represents stages of 25, 256, 756, and 1,100 kilometers. Short term issues like minor toe delamination (around 25 kilometers) to long-term damage to midsole foam (around 756 kilometers) are represented along the timeline.

The graph below plots shoe end-of-life distribution for testers, with a majority of testers (70.45%) getting 800 to 1400 kilometers out of their test shoes — that’s roughly 500 to 870 miles.

Nnormal Kjerag distribution of lifespan

The lifespan distribution in kilometers of the NNormal Kjerag from the brand’s study. Screenshot from brand website.

So what does a NNormal customer do with their shoes when the useful lifespan has expired? The company offers a couple of options including its No Trace program to let runners send back their shoes for repair or recycle. In Europe, customers can locate a cobbler to have shoes resoled by a partner trained to repair or replace Vibram outsoles (the Kjerag uses Vibram’s Megagrip rubber) as well as other material failures.

While some of the durability survey’s biases are unclear, NNormal is at least taking the admirable steps of talking concretely about the durability of its flagship product on a public stage in addition to choosing materials – such as Matryx uppers and a more durable midsole material in the Kjerag – for its shoes with product lifespan in mind. The brand is also currently studying the durability of its other primary model, the Tomir, in a similar manner.

In the future, it would be great to see a standardized protocol developed so that other brands could publicly share data on their shoes’ durability and, eventually, large scale external-to–brands testing that an independent organization collects, aggregates, and shares. Seeing robustly sourced average shoe lifespan, cost-per-mile, and resource-per-mile metrics would allow consumers to make better informed choices and, quite possibly, influence product designers, brands, and the industry at large to consider product durability more strongly.

One can dream. For now, kudos to NNormal for taking a first step.

Call for Comments

  • How strongly do you consider durability in your shoe and running gear purchases?
  • How does durability rank in comparison to price, performance, environmental impact, and other factors?
Craig Randall

Craig Randall is a Gear Editor and Buyer’s Guide Writer at iRunFar. Craig has been writing about trail running apparel and shoes, the sport of trail running, and fastest known times for four years. Aside from iRunFar, Craig Randall founded Outdoor Inventory, an e-commerce platform and environmentally-driven second-hand apparel business. Based in Boulder, Colorado, Craig Randall is a trail runner who has competed in races, personal projects, and FKTs.