OneStronger: How two brothers turned a nightclub in Ulm into a Training Club

About OneStronger

OneStronger is a boutique fitness concept from Ulm, founded by brothers Felix and Kilian Fahrenschon. Since late 2025, an upscale nightclub has transformed into the OneStronger Training Club during the week. Since summer 2026, HYROX RiverSide has added a second pop-up right on the Danube. The motto: We Train as One. Stronger Together.

The idea: A club that stood empty during the week

For Felix and Kilian, sport has always been more than a hobby. But the spark for their idea came from a completely unexpected direction: through a contact, the two met the manager of a nightclub in Ulm.

“The club stood empty during the week, had a really great sound system, enough space, and the lighting was already there. So the idea came up: Why not train there?”

After visiting top studios in Munich, the brothers deliberately developed their own style. From the decision to the opening, it took just two and a half to three months.

At the heart of it all is their own conversion concept: in two to three hours, the club becomes a training space. Everything that looks like nightlife disappears, and mirrors and equipment come in. Some members still haven’t discovered that the bar is hidden behind the mirror.

“The idea only works because it’s not a classic nightclub. It’s a very upscale boutique club with a concrete look, steel, an artificial tree in the middle and a smoking ban. A super clean space.”

On top of that, the location sits between two of the most popular cafés in town. At OneStronger, coffee, matcha and training simply belong together.

Why bsport was there from day one

In Munich, the brothers noticed that many leading studios work with bsport, while most studios in Ulm used other systems. This is exactly where OneStronger wanted to stand out: with its own app, an all-in-one package and no marketplace.

“We looked to the best studios for orientation. We love how exclusive it is: people are in your own world, with your own app.”

Growth potential was just as important, because it was clear from the start that this wouldn’t stay a single concept. Onboarding with videos and a dedicated Account Manager was well structured, and today almost everything runs independently. And if a question does come up, the chatbot is there to help:

“We solve 9 out of 10 cases directly with the bsport chatbot. It works really well.”

Kilian takes care of class scheduling, finances and bookkeeping, and works with bsport every day.

“I love the calendar overview. I check it every day and get a really good feel for our capacity and the share of Wellpass bookings. I’ve also built my own dashboard, because I’m responsible for the numbers.”

Members notice the difference too: “We get a lot of compliments on how cleanly we work. bsport is part of that, the booking process is great.”

Three times as many members in nine months

The number of members tripled in around nine months. And when even German public broadcaster SWR reported on OneStronger, it was clear: the concept had struck a chord. The biggest driver? The brand and the culture behind it.

“We come across as premium, but when you arrive, you’re warmly welcomed. You don’t need to be in top shape to train with us. We’re happy you’re here.”

You can feel this culture in the training, too. Mat training at the club is strength-based but feels like a party: club beats, a light show and an energy that carries you through every round, no matter what level you start at.

In summer 2026, the next step followed: HYROX RiverSide, an official HYROX Training Club set up as a pop-up at the boathouse on the Danube, launched in just three weeks. Here, too, you can see what OneStronger stands for: people who stand on competition podiums train side by side with people doing sport for the very first time. And the two locations complement each other perfectly: in good weather, everyone heads to the water, in bad weather, back to the club.

“You have to understand that community takes time and has to be authentic. You can’t force it. At our first events, almost nobody knew each other. Today, 70 people show up and everyone greets each other. That’s why it’s a core part of our concept, and we deliberately invest a lot in it.”

One clever building block is the Run Club. Taking part is free, but sign-up runs through OneStronger’s own app. This way, the team brings new people directly into its own ecosystem, independent of Wellpass, and builds a relationship that goes beyond a single workout.

Today, Felix and Kilian are both fully self-employed, yet still coach on the floor themselves. And the next studios are already in the works.

Tips for anyone who wants to open a studio

1. Love for detail

If you only look at your margins, you’ll always find something to cut. But investing in your brand and presence pays off two and three times over.

“If you say you’re a boutique studio, then you have to do boutique. And boutique is simply love for detail.”

2. Start professionally from day one

When choosing your booking software, it pays to think long-term from the very beginning.

“I’d recommend working professionally from the start. If you begin with a different tool because it’s cheaper and have to switch after six months, the effort ends up being much bigger.”

3. Be authentic, but build a brand

Social media is the most important channel for getting people into your studio at opening. Many people decide there, before their first visit, whether they like the people behind the studio. So showing personality helps enormously. Still, the studio shouldn’t be seen as “Kilian’s gym” or “Felix’s gym”, but as a brand of its own with a strong team behind it.

“The brand shouldn’t always depend on just one person. Otherwise everything stands or falls with how likeable they are.”

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What about you?

What if your idea becomes the next studio everyone’s talking about?