The Prototype Phase with MTB Pro Claudio Caluori

The Swiss rider became famous primarily for his spectacular "Course Previews," in which he takes on the world's most challenging downhill tracks while providing live commentary. But Claudio is more than just an entertainer: even during his active racing career, he delved deep into the technology of his bikes. Especially in downhill racing, where the smallest adjustments to geometry, suspension, or weight can be crucial, he developed a keen sense for materials and setup. This expertise makes him a sought-after test rider today, capable of quickly assessing whether a bike has potential — or still needs fine-tuning. In this part of our article on the development of the R.EXC, we focus on the next crucial phase: real-world testing with the first prototype bikes. After all, even the most sophisticated technology is worthless if it can't fully convince on the trail.

This is where Claudio Caluori comes into play. Since 2022, he has been supporting ROTWILD in further establishing the e-mountain bike as a performance-oriented sports machine. His vast experience and unique riding instinct help bridge the gap between theory and practice.

Why is this step so important? The development of a bike doesn’t end in a computer model or a lab. Only under real-world conditions on the trail does a bike prove what it’s truly capable of. Claudio takes us along on this exciting journey — offering insights into the technical details of the R.EXC and sharing his personal impressions of this unique bike from the very first ride.

First Impressions: Unconventional Elegance

By early summer 2023, the time had finally come: the first fully rideable prototype was ready — custom-built for Claudio. Just a short distance from the company headquarters, the first test ride took place on the team's home trails. This was the moment when theory met reality, and Claudio experienced the bike in action for the first time.

"I still remember very clearly the first time I saw the prototype — I immediately knew that I was looking at something special," recalls Caluori. "The design was extraordinary — unusual, almost futuristic." But that was exactly what intrigued him. "The eye needs time to adjust to something new," he explains. "This applies to bikes just as much as to cars or architecture. Sometimes, skepticism is the first step toward enthusiasm."

And that enthusiasm didn’t take long to set in. From the very first test ride, Claudio’s intuition was confirmed: this bike is different. It’s not just another model in the vast e-MTB market — it’s a technological milestone.

Claudio’s Testing Philosophy: More Than Just Full Throttle

The tests took place primarily in Claudio’s home terrain — the Swiss Alps, a true paradise for mountain bikers. With everything from long road climbs to technical trails and full-scale bike parks right at his doorstep, he had the perfect conditions to put the bike through its paces. “This is ideal for really testing a bike to its limits. I try to ride it in every possible condition,” he explains. “That means long climbs, technical trails, rough downhills, and, of course, big jumps in the bike park.” But it’s not just about speed — it’s about the all-around versatility that defines an Enduro bike. How does it handle on climbs? How controllable is it in technical sections? And how does it feel at high speeds on the descent?

After just the first test runs, the bike’s character became clearly evident. What impressed Claudio the most was the prototype’s uphill performance. “That really left me speechless. I climbed sections I hadn’t managed in four years —on my very first attempt. The new rear suspension system makes all the difference.”

The Mid-High Pivot System: A Kinematic Revolution

But what exactly makes the Mid-High Pivot system so revolutionary? In short, it fundamentally changes the rear suspension’s kinematics. Thanks to the unique pivot placement, pedal kickback is significantly reduced, and the rear wheel remains stable on the ground even in rough terrain. The result is a confident and efficient riding experience — both uphill and downhill.

"You immediately notice how powerful the bike is on climbs. It doesn’t lose any energy, no matter how technical the trail is," enthuses Claudio. "And on the descent, it feels like riding a downhill bike. It’s incredibly stable and gives you absolute confidence."

But the system doesn’t just enhance performance — it also boosts versatility. With a well-thought-out geometry and a powerful motor, the prototype becomes the perfect all-rounder. "This isn’t a compromise bike that does a bit of everything but excels at nothing. It’s top-tier in every discipline. This level of versatility is truly special!" emphasizes Caluori.

Technical Details and a Passion for Documentation: Claudio’s Testing Routine

During his tests, Caluori meticulously documented his experiences. "After every ride, I wrote reports and sent feedback to the development team," he explains. "I covered everything — from battery performance to handling in technical sections."

One key focus was the balance between motor power and geometry. "It’s crucial to understand the strengths of the motor without neglecting the bike’s geometry. The motor makes a big difference on climbs, but on descents, geometry and suspension take over."

In-depth feedback is essential during the prototype phase as it bridges the gap between theoretical design and practical use, allowing for targeted optimizations. "The collaboration with Lutz Scheffer was very intense, even though we mostly communicated via email and phone. After every test ride, I sent him my impressions and suggestions for improvement — whether it was regarding geometry, battery efficiency, or ride characteristics." What particularly impressed him was the team's responsiveness: "You could literally watch how solutions emerged directly from my suggestions."

For Claudio, Lutz was much more than just a designer – he saw him as a visionary who meticulously thought through every technical detail. "My job was to test his theory on the trails and find out what really works in practice," explains Claudio. This collaboration was especially evident in the optimization of the battery: Claudio kept track of the battery range in different riding situations and provided precise data that the engineering team incorporated into further development. The combination of the engineers' technical know-how and Claudio’s practical experience on the trails created the perfect mix to not only continue developing the R.EXC but also bring it closer step by step to production readiness.

Looking Ahead

Claudio’s commitment to pushing the R.EXC to its limits and making final optimizations always had the bigger goal in mind: preparing it for the next major step — the competitive racing scene. "Designing a bike on paper is one thing, but perfecting it in practice is another," explains Claudio. "My job was to ensure that it not only rides well but is also absolutely competitive under real-world conditions."

In 2024, the R.EXC entered its third development phase and was handed over to the ROTWILD Schwalbe Gravity Team for World Cup use. With this transition to the racing team, the next crucial testing stage begins: further developing and refining the bike in the intense race environment at the highest level.

How does the R.EXC perform under competition conditions? What impressions does the team gather? In the final part of our series, Torben Drach, rider for the ROTWILD Schwalbe Gravity Team, gives an insight into the first race experiences with the prototype and how Claudio’s work has paid off on the track.