INTERVIEW - Behind the scenes of Cast MTB with Thomas Callaghan

We had the great pleasure of interviewing Thomas Callaghan, head of the tire department at Cast MTB.

Thanking him in advance for his generous support, we wanted to ask him specific questions to better understand the work that went into achieving such a high-performance, racing-focused result for their Antagonist and Protagonist tires.

[EDOARDO – MTBWORKSHOP]

[THOMAS – CAST] Hello Edoardo! Nice to meet you, delighted to speak to you. I will jump straight into the questions.

[EDOARDO – MTBWORKSHOP] What approach did you take in developing Cast tires, considering the racing feel so clearly noticeable even to us ordinary riders?

[THOMAS – CAST] In short, our approach was to utilise the most advanced rubber technology available globally and to be very direct in our design objective: to create something that is, as you say, noticeably different. Our tires feature details that may appear relatively small to the eye, but through extensive lab and trail testing, we know these details add up to a ride feel that is truly different.

At the core of any high-performance tire is rubber – I can’t stress this enough. Without access to world-leading rubber technology and the infrastructure to develop it properly, pushing the boundaries of grip performance becomes almost impossible, and that objective was critical to us. That’s why we partnered with Pirelli. They are global leaders in rubber compounding, and we’ve taken specific technologies developed in motorsport and successfully translated them into the MTB world.

[EDOARDO – MTBWORKSHOP] Did you conduct a targeted study to offer instant grip from the first few kilometers?

[THOMAS – CAST] This really comes down to the details. The rubber compound is core to this, but on top of that we’ve taken an innovative approach to tread design that adds significantly to the overall ride feel. You’ll notice how sharp and textured the knobs appear. We’ve implemented design features that increase the definition of each knob, which has a direct and noticeable effect on how they engage with the ground and generate grip. We’ve also developed features that are unique to our tires. One example is the ramped pockets on the side knobs. Traditionally, recessing a pocket can marginally compromise side knob strength, but it adds an extra gripping edge. This feature is most noticeable on slippery rocks and roots. By ramping the recess, we retain the structural strength of the side knob whilst gaining that additional gripping edge on the surface. Small details, but again all add to that overall performance increase.

When you start stacking all of these small details together, they create the distinct, confident feel we’re aiming for. We’re here to try new things—and push what a tire can feel like on the trail.

[EDOARDO – MTBWORKSHOP] Our test was conducted with an Antagonist setup at the front and rear. Would you recommend this setup generally or only for certain uses, considering the possibility of using the Protagonist at the front?

[THOMAS – CAST] It’s very dependent on terrain and riding style. The Antagonist front and rear setup will roll slightly faster than the Protagonist, but still delivering a very aggressive feel, particularly for riders in loose or mixed terrain, where it really excels. Essentially, the Antagonist is designed to offer a highly consistent and predictable level of grip.

The Protagonist, by contrast, delivers a deliberately different ride feel, which we describe as varying levels of cornering support. As you move through the lean angle, the support transitions from strong, to an intermediate zone of support, and then back to strong as the tire engages the side knobs. We developed this sensation through extensive work on knob size, placement, and multi-rubber compound construction at the base of the knobs. The feedback on this has been overwhelmingly positive. Largely it shows that it helps riders better feel where they are on the tire, allowing them to push into the grip with more confidence—especially at higher lean angles.

If you want a stronger gripping front tire, whilst looking to gain some rolling speed performance, match it with the Antagonist on the rear.

[EDOARDO – MTBWORKSHOP] We noticed great smoothness despite the large profile of the knobs. How did you achieve this?

[THOMAS – CAST] Testing is a huge part of our ethos. The access we have in Pirelli offers us the ability to develop concepts and test them, right in Milan. So before we take to the trails, we have already been able to simulate, test and refine. You learn the most from ideas that don’t work, we encourage both our athletes and engineers to try push the boundaries. If it doesn’t work – great! We learn and we go again. Our tire lineup presents something we have developed behind the scenes for quite sometime. We are gravity riders, we want to feel confident on the trails when the trails really get tough, but we also want to be able to cycle back up the hill after! The Antagonsit helps that balance of maximum grip and pedalling efficency when cycling on your main centreline.

[EDOARDO – MTBWORKSHOP] How much did the feedback and reports from your pro rider tests influence your technical choices?

[THOMAS – CAST] Testing is a huge part of our ethos. Through our partnership with Pirelli, we have access to advanced rubber development and testing facilities in Milan, allowing us to develop concepts, simulate performance and refine designs long before we ever hit the trails. We have developed reliable processes to test tires that traditionally weren’t available. Advancements in areas like 3D printing and testing machines have really elevated how we test.

You often learn the most from ideas that don’t work, so we actively encourage both our athletes and engineers to push boundaries. If something doesn’t work—great. We learn from it and go again. The tires in our lineup are the result of concepts we’ve been developing behind the scenes for quite some time.

[EDOARDO – MTBWORKSHOP] What should we expect from Cast in the future regarding tires, considering the high performance offered and the wide versatility we’ve already seen?

[THOMAS – CAST] You can expect continued technical advancements in both tire technology and how we ride bikes. We don’t believe in offering a large, overly complex lineup designed around very narrow use cases. Instead, we focus on designing for the core riding group. At heart, we’re gravity riders. We want maximum confidence when the trails get tough.

Our goal is to deliver tires that offer outstanding all-round grip, strong carcass protection and the reliability riders need when trails get tough. We welcome the complexity of tires in our development process, so that we can make tire choice simple for our customers.