Words by Mike Stuart, On staff

Nils Altrogge has no right to look fresh-faced. On’s Head of Innovation Portfolio has had a hectic couple of weeks, and I’m the last in a long line of interviewers asking him questions. Despite all this, he is energized and relaxed. We’re speaking days before the release of the new Cloudsurfer running shoe. It’s a big moment at On – and for Nils (pictured above in white) and the innovation team. It represents the end of a years-long project that meant a complete evolution not only of On’s signature CloudTec® cushioning technology, but how On shoes are designed. 

To fully understand the significance, you need a little context about CloudTec®. This original, proprietary technology is the reason On exists. It’s responsible for the unique “running on clouds” sensation On shoes are known for. With its unique ability to give your feet a soft landing and a powerful push-off, CloudTec® has put more performance – and fun – into running for millions around the world. And with the new CloudTec Phase® technology in the Cloudsurfer, Nils and his team have changed it completely. Isn’t this a bit of a risk?

“We’re always looking for ways to improve our products – for the next innovation,” says Nils, who’s worked with On for 10 years. “We don’t know any other way.”

We’re at the On Lab in Zurich, Switzerland. Beginning our tour in the Sports Science Lab, we pass someone sprinting on a treadmill tilted at an impossible angle. The man behind the mask, I realize, is On Trail Team Athlete and Testing Specialist Antoine Charvolin. This explains the ability to run at such an angle. A top 10 finisher at the Marathon du Mont Blanc, Antoine is no stranger to incline. The story of the new Cloudsurfer and CloudTec Phase®, Nils tells me, began on this very treadmill. 

“We set out to create a shoe that as many people as possible will enjoy running in,” he says. “This meant focusing on what makes a run feel good for runners of any experience level: cushioning and ‘ride’.

“By ‘ride’, we mean the rolling transition of the foot as you run, so from landing on your heel to pushing off from your toes,” Nils explains. “The smoother this rolling motion is, the less energy you lose while your foot’s on the ground. This is also correlated with running efficiency. When you have an efficient rolling motion, it feels smooth, like you’re gliding. 

“As a comparison, rollerskates would be the ultimate ride. And if you’ve ever walked around in ski boots, you know what the other end of the scale feels like.”

Having defined the focus on these two aspects of running sensation, the On sports science team set about exploring exactly how shoe design affects runners’ perceptions of cushioning and ride. 

Over a period of several years, around 1000 runners of all levels – from beginners to pro athletes – had their treadmill runs digitally captured and analyzed before they were quizzed about perceptions of cushioning and ride by On’s sports scientists. The resulting data enabled the next stage in the process – which is what sets the Cloudsurfer apart from every On shoe that’s gone before it.

We head to another corner of the lab, where Simulation Engineer Ben Lane is sitting. Nils introduces him as “the only person at On who doesn’t work from a laptop.” Instead, Ben used a giant, purring desktop machine for running the computer simulations that enabled the creation of CloudTec Phase®.

One of the benefits of CloudTec® is its adaptability. The cushioning can easily be verified depending on what the shoe is for. With the new Cloudsurfer, the goal was to create a new feeling for road runners. And to this end, CloudTec Phase® is the first version of the technology to be optimized with virtual modelling during development.

The computer model used is unique to On, and uses software known as finite element analysis (FEA). The name refers to the large numbers of individual elements with clearly defined (finite) parameters. Already used in the aerospace industry and to engineer Formula 1 cars – it made the perfect partner for developing performance footwear. 

On his screen, Ben shows me a simulation of a runner’s leg landing. The foot, leg, and shoe are comprised of a huge number of tiny blocks in an intricate digital mosaic. These, Ben explains, are the “finite elements” and, to give a sense of the level of detail, there are around 2.8 million of them. “Modeling the different materials that need to be considered – from the foam cushioning of the shoe, to a runner’s muscles and bones was a big challenge,” Nils says. “Then we had to correlate this with the data from the treadmill runners, which is complex. It was only possible because of our combined knowledge across sports science, biomechanics, engineering, statistics and data science. When you step into the shoe, you’ll understand the effort.” 

Ben can make tiny adjustments to the design of the shoe in the software and then accurately simulate the impact on a runner’s body – and their likely perception of comfort and ride. 

An algorithm in the software helps identify potential enhancements for the next simulation. How to adjust the size and angulation of the spaces that create the Cloud elements in CloudTec Phase®, for example, or the distance between them. The resulting design creates a cushioning system that compresses to provide a solid wave of complete cushioning through every phase of your stride when you run (hence CloudTec Phase™). 

Running each simulation takes even Ben’s high-power desktop computer 10 hours. And the model was run hundreds of times before the team got close to the final result. If that sounds time-intensive, consider the alternative: prototyping processes can take up to six months. The virtual alternative is not only faster, but more effective, more sustainable and produces less waste.

Of course, a simulation of a shoe is no use unless the theoretical feeling can be replicated in real life. Which is why the next stop is the workshop, known as the “Maker Space”. On the way out, we pass legendary Norwegian coach Olav Aleksander Bu. Known for his scientific approach, Bu is the coach of On triathletes Gustav Iden and Kristian Blummenfeldt. Between them, they hold the current Ironman, world and Olympic titles. Iden offers up ultimate proof of the Cloudsurfer's ride: he's already using it in his training shoe rotation.  

After the clean lines and glowing lights of the Sports Science Lab, the Maker Space is a stark contrast. We’re welcomed here by Thor ter Kulve, who runs the workshop. Thor’s tools (yes, including hammers) line the walls, and there’s a strong smell of solvent. But look past the old-school equipment, and you find advanced pieces of kit, from 3D printers to laser cutters. This is where Thor and team quickly create raw prototypes to confirm the results of a simulation. These early versions of a shoe are known as “monsters” at On because, while they are an effective first test, they’re anything but pretty. 

But making a raw prototype that feels good is one thing. Transforming it into a real first shoe at a production facility is a different challenge. The first prototype that came back from the injection-molding machine at the manufacturing partner in Asia felt like a brick. As Nils explains, the shoe also has to be designed for the production process. This is where On’s Head of Design for performance running products, Olli Hirvonen, and his team are the experts. They took the first facility-made prototype back to basics by making some manual adjustments and adapting the materials used. Some further checks and a few prototypes later, and the desired sensation had created in a shoe that was ready for full production.

For the final part of our conversation, we move to the On Lab’s innovation floor, which is where the team get their office work done. As we’re talking, On Co-Founder Olivier Bernhard, the inventor of CloudTec®, stops quickly to say hello. On the eve of this significant moment for the innovation team, he, like Nils, is reassuringly relaxed. 

I ask Nils how it felt when he first tried a shoe that delivered the sensation of cushioning and ride they’d been seeking. “Euphoria” is his reply.

Discover the all-new Cloudsurfer with CloudTec Phase®. Featuring computer-optimized cushioning for soft landings and a smooth ride, it’s also engineered for a lower impact on the planet. The Cloudsurfer is made using 30% total recycled content by weight and a technique  called dope-dyeing that uses approximately 90% less water compared with traditional dyeing methods.