What is a durable product?

We don't get attached to throwaway products. It's true in sports and beyond. On the other hand, we love products like your grandma's old tennis racket that is still ready to rally despite its age.
Or your trainers, always timeless, ready to go and perfect for running, we love them too.
Even that dusty bike that brings back a thousand memories with a single look and just needs to be aired up to take you on your next adventure. And who could forget the trusty T-shirt, faded of course, but which still looks good on your shoulders despite the years. That's how sports products win us over, by standing the test of time. Why? Because they are loyal, they stay the course and we share our lives with them. The key word here is: durability.

Sustainability has two meanings. First a global meaning, both complex and essential, defined by the United Nations Brundtland Commission in 1987 as "meeting the needs of the present without compromising the ability of future generations to meet their own needs". This definition underpins the idea of economic, social and environmental stability in our lifestyles(↿). This is the political meaning of sustainability. The second, narrower meaning of sustainability coexists and combines with the first through the idea of duration, of the "quality of being durable" if we follow the dictionary definition.
It is from this second meaning that the question emerges that DECATHLON teams strive to answer every day: "How can we improve the lifespan of our products?". The stakes are very high, since the goal is to make the world more sustainable, down to the smallest detail, through products that last.

(↿) Sustainable development is based on three pillars (economic, social and environmental) and yet the circular economy is the solution to achieving all three at the same time.

"What we call sustainability," explains Lucile Cazaux, project manager at DECATHLON's sustainable development Hub, "is the durability of a product that cannot be repaired, its strength and its performance over time. We try to estimate a minimum number of uses that a product can endure before the end of its lifespan, with the goal of optimizing this number."

Therefore sustainability at DECATHLON refers strictly to the lifespan of the product. It does not include repairs, rental, second-hand, trade-ins or anything that would keep the product in use for as long as possible.

Here, durability is the responsibility of design teams, who are charged with creating the most sustainable products whose qualities stand the test of time. DECATHLON teams rely on an evaluation method that lets them observe, test, interpret and measure the lifespan of products.

The first step is to analyse an end of life product, observe its eventual defects and reference them according to their type. It's all about making a diagnosis.

At this time, design teams will define the problems raised by users to create a list of defects and their importance. A product that wears out or breaks too quickly will alert design teams and warn them of a production defect, otherwise called infant mortality. In this specific instance, the quality service teams will be responsible for correcting the defect. Once this type of defect has been corrected, we carefully analyse wearout and accidental defects by asking the following questions: how is the product used? What are the causes of a product's end of life? What is the product's end of life? Take a T-shirt as an example, will a hole be the cause of its eventual end? Or will it be a fading colour? Or fraying material? It's not always easy to place blame.

Reproducing wear with tests
The second step involves developing fatigue, abrasion, corrosion and ageing tests so that we can artificially age products and evaluate their durability in the lab. With textile products for example, different knits are tested to age their fibres and evaluate their resistance to wear.
Alongside lab tests, wear tests are also conducted. Testers play their sport with the product and complete a follow-up questionnaire that helps us evaluate the different factors that contribute to wear and accidental defect.
Designers also strive to find a scientific link between, on the one hand, the diagnosis and field tests and, on the other hand, the lab tests
Define a product's lifespan

The final step of the evaluation method is interpreting all the data from the diagnosis and the various tests conducted on the product. As a result, certain product families, like fishing reels, stand up paddle boards and kayaks, will have a lifespan quantification, or the minimum number of uses guaranteed by a product.

"What we want to stress," Lucile adds, "is that we are working tirelessly to improve the durability of our products." The important thing is to use the products as long as possible, to see that they last and highlight all the scientific work that made it possible. This makes us more comfortable with what we communicate to our customers and users. »

The durability evaluation method was designed to adapt to a wide range of DECATHLON products. As a result, design teams are able to apply it to their product typology. Amandine Vallantin, sustainable development manager of the Decathlon sock design team, and Lucca Pastorino, testing engineer from the same team, took this approach.

The sock was developed in 2 phases. The first phase found a diagnosis via a survey of 2800 people. Amandine and Lucca created a questionnaire in which they asked users how satisfied they were with their socks, their lifespan, defects they had noticed and their wearing zones to determine users' needs and increase the product's lifespan. They found that there are three main wearing zones: the heel, sole and toe. Users also reported three recurring problems: their sock shrink, pill and tear.

Starting from this information, specific tests for socks were implemented. Amandine and Lucca visited the Institut Français du textile et de l’habillement (IFTH), a specialized external body equipped with specific machines, to carry out a battery of tests. They were able to do an abrasion test on the shape: this is a foot shape that is worn down with abrasive paper on particular areas of the sock. Seventy DECATHLON socks were tested with this process to obtain a representative panel and compare the socks to each other.

"The long-term goal," says Amandine, "is to have all our socks tested".This represents about 200 different sock models. At the same time, we want this process to be replicable with other processes, like T-shirts and gloves, and to be able to support teams in adapting the method to their limitations and expectations. »