This article was first published in Rouleur Issue 141 and was produced in collaboration with BMC
Grenchen is a quiet Swiss town that sits at the foot of the picturesque Jura mountains and has a long history of precision watchmaking. It’s modern, prosperous and well connected, with two railway stations whose trains always arrive and leave on time. It’s also home to the superfast Tissot Velodrome, where multiple Hour records have been set since it opened in 2013 and, directly opposite, BMC’s smart headquarters. But if you walk a few hundred metres down the road, you’ll find a much less corporate place that turns the Swiss stereotype on its head: “No idea is too wild, no detail too small and every innovation, from micro travel technology to integrated cockpit systems, is born from the desire to turn raw materials into unforgettable rides.” That’s the mission statement of BMC’s Impec Lab, and that’s why we’re here.
Pushing through the frosted-glass doors with their ‘personnel only’ warning sign, you enter a compact maze of half-finished carbon parts, fatigue testing machines, 3D-printed prototypes, sliced-up frames and Frankenbikes with adjustable geometry and bolted-on suspension. This is where ideas are subjected to a kind of accelerated natural selection. Here, nothing is sacred, everything is possible – and only the extraordinary survives.
“We’ve learned that if we can’t validate ideas quickly, we’ll never try enough of them,” says Stefan Christ, BMC’s head of research and development, whose surname rhymes with ‘fist’ rather than the son of God, and who is known in the company simply as ‘Stiefu’. “Our ambition is, out of everything we try in the Impec Lab, one product makes it to the commercial market.” Christ and Peter Stämpfli, the Impec Lab manager, have in 15 years built this unique facility around risk, discipline and scientific rigour.
There are currently ten projects running, Christ explains. Each of these projects is sprawling in its scope, all of them demanding an intensive and sustained level of analysis that involves designing custom test protocols as well as one-off components in carbon and metal. F1 teams have their skunkworks for conceiving radical supercars – BMC has the Impec Lab.
The first bike we see is in fact a direct result of an F1 collaboration – it’s the strikingly angular Speedmachine, a BMC project with Red Bull Advanced Technologies that aimed to create the world’s fastest bike. It was made here in the Impec Lab and is now leaning up against the wall of the composites booth – a separate room within the lab – along with a row of other prototypes: there are hardtails with mechanisms sprouting from head tubes; road frames with adjustable bottom brackets; gravel bikes with setups no sane rider would ever consider.
“When someone has an idea, within two or three weeks we want to be out testing it,” explains Christ. “We have CNC machining, we have carbon manufacturing, so we can really do this very quickly.”
Speed is not only crucial to the way the lab operates – it creates a working culture. Christ and Stämpfli have seen countless ideas come and go, and they’ve also learned to check their own cynicism.
“We have to force ourselves not to say, ‘We’ve tried this before, it doesn’t work,’” Christ says. “But the environment changes. Technology changes. Bikes change. If an engineer brings an idea, even one we don’t believe in, we push ourselves to prove it one way or the other. This is the culture: we want to allow everyone to validate their ideas and often then, by building a prototype, you develop more new ideas and a combination of ideas. You also have things that ended up somewhere in a box and then two or three years later you realise now is a good time for it.”
Christ holds up a mountain bike frame that looks as though it has survived a mad experiment – which, in a sense, it has. It’s an adjustable-geometry hardtail prototype, designed to replace what would otherwise be multiple test frames. “We prefer to do one prototype that we can adjust rather than five, six, seven different ones. We can change bottom bracket height, reach, rear-centre length, and head tube angle,” he says. “And the key is being able to do it on the trail. Bikes now are very refined, we are talking about small nuances that you can only judge on the same day in a very short timeframe. As humans we adapt very quickly to something and if you want to catch the differences you have to be quick with the adjustments.” The adjustments are made via plates, bolts or sliding inserts. It isn’t pretty, but it’s fast.
Knowing how to make a prototype quickly and reliably is in itself a speciality of the Impec Lab. “It doesn’t have to be nice, it just has to be functional,” says Christ. “If you want it to look nice you have to make a mould. For example with wet lamination, you just need to ink the carbon fibres with resin and you wrap it to compress them, which from a structural point of view works very well. But the outer shape is not very controlled.”
New technologies such as 3D printing are also helping. “We can 3D-print cores, which go inside the carbon laminate. There are even some projects where we made entire prototypes out of metal. 3D printing is still too expensive for production but for one-offs it’s more viable.”
The Impec Lab stays involved once a frame is in development or production, performing carbon composite analysis on BMC frames made by its partner in Asia. They’re checking layup consistency, quality, looking for voids, compaction, whether transitions are smooth, if bearing seats are formed perfectly and whether larger load-bearing structural elements such as the bottom bracket are properly connected.
Christ is a mechanical engineer specialising in composites, but it’s Jürg Affolter who is tasked with this. He’s not in the lab today but we’re allowed to look inside his composites area as long as we don’t touch anything. “He has been doing layups for 20 or 25 years,” says Christ. “He did the TT01 time trial bike, the very first developed for the Phonak team in 2004.” This was a groundbreaking model for BMC, especially when Tyler Hamilton won Olympic gold on it at the end of that year. The frames were manufactured in Switzerland. “He has such expertise even in judging where we might have a problem in the future, and we want to eliminate those things at prototype stage.”
Next we’re shown a long bench on which a carbon frame has been cut into slices and neatly arranged like geological samples. It is a production Teammachine R raced in 2025 by Tudor Pro Cycling rider Marius Mayrhofer. “We want to see if anything changes after a season of professional racing, if it’s the same as it was when it was in development and also to anticipate future projects.” Each precisely cut slice has its weight written onto it in white paint marker. “For example, the head tube should weigh 150 grams out of a total 900 grams. If we see a head tube that’s 160 grams, that’s heavy.”
Was Christ’s team happy with this particular frame? “Yes, it was very consistent with the development stage and, honestly, with the Teammachine R we are super, super happy. For us it’s a new benchmark. That’s also why we want to be sure we have all the correct data to move forward. When you have something that really works you want to make sure it is setting a new foundation on all levels.”
Originally the building in which the Impec Lab is located was set up to produce carbon frames, and it did this from 2008 to 2014. Manufacturing was transferred to Asia after that because in Switzerland it was no longer cost efficient. BMC’s former owner, Andy Rihs, had spared no expense when he set up the Impec Lab with the aim of building the best bikes in the world.
Although it became economically unviable, technologically it left behind a unique legacy. “It is the reason we are here now,” says Christ. The CNC machine is also a leftover from the production days, and at one time there was a huge filament-winding machine here too.
At the far end of the lab is a Mad Max-like collection of gravel prototypes that should not exist in anyone’s imagination – but of course it’s the Impec Lab’s job to imagine them first. There are wheel/tyre/ suspension combinations that have never been seen before and, bizarrely, one of the bikes has a log wedged into its bottle cage in what looks like an impromptu Flintstones tribute. This, Christ claims, is not for any technical reason. It is from a campfire: the BMC test team, out with these bikes on the trails above Grenchen the day before, had a cheese fondue for lunch and someone stashed it there afterwards. Most likely it’s there to add weight for testing travel configurations – all in a day’s work for the Impec Lab.
“We wanted to see how the future of gravel might look,” says Christ. They tested BMC’s current gravel offerings against the next, unreleased generation. They were asking whether extra suspension is worth the extra weight. Or do fully rigid bigger wheels offer meaningful benefits? Where are the boundaries?
Stämpfli explains the philosophy behind these sessions: “Whenever we test, we also test something that feels too extreme. Because sometimes, that becomes the right direction.”
It’s happened before – the previous-generation Fourstroke geometry, a bold leap at the time, was the result of pushing prototypes into ‘surely too extreme’ territory.
As for BMC’s current triathlon bike, the Speedmachine: “It has such extreme numbers that we do not even publish them because if we did, no one would buy the bike. If we disclosed the steering geometry we would be blown into pieces. But everyone likes the bike, we like how it rides. We are so progressive that we believe people would not trust us or would think, no, it cannot work.” It’s an unusual upending of bike-industry marketing: hiding the numbers not because they’re unimpressive, but because they’re too far ahead of consumer expectations.
Stämpfli explains that the recent testing is linked to probably the biggest ongoing project of all, something that underpins all of the Impec Lab’s work, as well as the future of BMC’s R&D: how to measure performance in ways that actually matter. BMC treats measurement itself as an R&D project.
“Products are more and more refined, we are measuring smaller differences, and the differences are hard to detect. Human perception is limited. So you need to make sure what you measure makes sense. If you measure rolling resistance on a roller, that’s not the real world. But you still need repetition consistency and you need to find the best measuring tools.”
He continues: “We combine objective and subjective. For a pro rider a measurable gain is relevant, but for our regular consumers it must be something they can feel. We can’t tell them ‘this is a faster bike’ but then from the subjective test it feels slower. It might be relevant for the professional, but for empowering people to ride bikes and to have a great experience, it would be completely wrong. We live off our riding emotions, that’s our justification. Why else would we spend 10,000 on a bike when we could have almost the same for 2,000?”
It’s one of the most honest statements you’ll hear from a performance brand. People buy bikes because they want to feel something. The numbers alone can’t justify it.
Again, it’s that irony at the core of BMC: there’s a tendency to perceive the company as Swiss, understated, precise. Yet, says Stämpfli, “behind the scenes we are the opposite. Always progressive in geometry. Always first to push trends. We were first with dropped seatsays; first with integrated cable routing – we experimented with it in 2014 and brought it to market by 2016. Everyone has integrated bottle cages now, but we had them in 2019.”
“If you look through the UCI clarification guide,” Christ laughs, “there are many examples from BMC.”
It’s clear that innovation here is not a steady march of progress – it is more a series of controlled explosions. The right idea at the wrong time dies. A crazy prototype built ‘just to see’ becomes the next trend, a geometry once considered ridiculous becomes the industry standard, a ten-year-old suspension fork is the best thing ever to happen to gravel.
As we head back towards the exit, a photograph taped to a wall depicting a motorcycle with a large circular void through its centre catches my attention. “A design project,” Christ says. “Thinking without restrictions. What could the future look like?”
Whether or not BMC will create a bike with a hole instead of a seatpost is not the point (though never say never). The point is that the Impec Lab is not just for developing new bikes: it is where convention is challenged, where the boundaries are breached, where imagination goes ahead of engineering, literally where the future of cycling takes shape.
FROM LAB TO ROAD: HOW THE IMPEC LAB DELIVERED THE TEAMMACHINE SLR01
BMC’s biggest victories – the 2011 Tour de France win with Cadel Evans, the World Championships road race with Philippe Gilbert in 2012, Olympic gold with Greg Van Avermaet in 2016 and many more Grand Tour stages – were won with the Teammachine SLR01. The bike has been a continuous thread running through the company’s history, revisited, refined and reimagined every three years. Ever since the first generation in 2010 up until the fifth generation, launched last year, there has been someone inside BMC working on an SLR01 even when it isn’t officially in development.
Read more: The BMC Teammachine SLR 01: The fifth element
“Every three years, it’s like an open book,” says Stefan Christ, BMC’s head of R&D. “You work on it for two years, then you have a year where you’re not actively working on an SLR. Then you restart again.”
Christ has led the development of all five generations. Almost two decades on, he still oversees the decisions that shape what BMC’s flagship lightweight race bike becomes. The latest Teammachine SLR01 is outwardly an evolution rather than a revolution, but its significant improvements compared with the previous version are one of the clearest real-world examples of the Impec Lab’s obsessive approach to performance.
The headline number is huge: the new frameset is 16% lighter than its predecessor. In real terms, that’s 220 grams saved across frame, fork and seatpost, with the frame alone dropping from 810g to 700g painted. And, as Christ points out, the weight doesn’t come at the expense of what has enabled the Teammachine SLR01 perform at that top level.
“Stiffness was non-negotiable,” he says. “That’s true for all BMC bikes. The challenge wasn’t making it light – it was making it significantly lighter while keeping the same stiffness.”
Development of the new SLR01 began by asking a simple question: was BMC still building the same bike, for the same rider? The answer was yes – but the goalposts had moved.
“With the Teammachine R now established as Tudor Pro Cycling’s race bike, we wanted to create a bigger difference,” Christ explains. “So the cursor for weight moved higher. We set ourselves a very ambitious KPI.”
This decision immediately complicated the project. Christ and his team tested multiple competitor frames in the sub-700g category and found they were typically 20-30% less stiff than the previous SLR. “So we knew exactly what we didn’t want to become.”
The Impec Lab’s role at this stage is less about building and more about dismantling – literally cutting up competitor frames alongside its own in order to understand where weight is saved and where performance is lost.
In the next part of the cycle, out of the analysis comes a hypothesis: where the structure can be reduced, where tube shapes can do more work than material, and where assumptions are challenged. “Based on calculations our estimate was 690 grams, carbon unpainted. The real frame was 670 grams in the end.”
While materials continue to evolve, Christ is clear that the biggest gains on the new SLR01 came from tube shape optimisation rather than space-age fibres.“When you look at the new SLR, it’s slimmer in all dimensions,” he says. “If you reduce the overall surface by 20%, you can already save a lot of weight. But the question is then, is it still stiff enough?”
This is where simulation and human judgement combine. Finite element analysis (FEA) can optimise stiffness, but it cannot yet resolve the complex trade-offs between stiffness and aerodynamics in a single step.
“We can optimise stiffness or aero,” Christ says. “But we still need the human brain to link the two.”
Despite rapid advances in processing power and AI-driven optimisation, even BMC’s collaboration with Red Bull Advanced Technologies confirmed the same limitation: fully integrated aero-structural optimisation remains out of reach for the time being. “I would have expected it, but even they do not have a fully optimised tool. They need multiple tools and they connect them. Big Software will be working in this direction for sure.”
The third pillar of the SLR01’s “diet”, as Christ calls it, is cosmetics. This was driven by lessons learned from BMC’s ultra-light Masterpiece framesets, which have no cosmetic weight since their perfect raw carbon finish doesn’t require buffing and subsequent surface treatments.
“To reduce cosmetic weight, the frame has to come out of the mould in a very, very good condition ready to paint,” Christ explains. “That means perfect layers, clean transitions, no wrinkles.” This is where he sees the biggest manufacturing improvement of the last five years. Layups are cleaner, tolerances tighter, and the results closer than ever to BMC’s one-piece Mpc construction.
The result is a frameset that is not only exceptionally light for its stiffness level, but also aerodynamically improved – closer to the Teammachine R than to the previous SLR, thanks in particular to a dramatically slimmed-down head tube.
“At zero yaw, the Teammachine R is still faster,” Christ says. “But for most riders who see higher yaw angles because they simply go slower, the difference is small.”
Before a physical prototype exists, the new SLR01 lives for months as a digital render: it’s eight months of simulation and competitor analysis before the first real carbon frame is made. “We refine the surfaces with industrial designers,” Christ continues, “which is micro-tweaking to make the bike look nicer. Then we simulate the final-final shape just to make sure the change we did had no negative impact. And from here the physical prototype starts, where we define the carbon layup.”
Perhaps what’s most surprising about the simulation process is just how accurate it is. The real frame, as Christ mentioned earlier, turned out to be 670 grams compared to the 690 grams predicted by the computer.
“Today, with FEA, you can simulate weight almost exactly,” he says. “In some areas you don’t simulate because you know you can make the dropout slimmer and smaller so you take five grams from there. It’s a combination of simulation and anticipation.”
Next comes the laminate plan – how the carbon fibre patches are to be laid up. “For the Teammachine R, I spent six months on the laminate plan,” Christ says. “The SLR01 was similar, because we had such ambitious targets.”
Computers indicate where material is needed, but for the manufacturing itself the patches have to be simplified. “Basically you define those plies with paper, you scan them for the digital cutter, you apply it on the frame and you see how they lay, if it’s folding or not. The computer analysis just gives you pictures but you have to create a shape, cut it… it is a lot of work but it’s the only way you get to the optimum.”
It’s a lot of work and most of the brands leave this part to their carbon manufacturing partners in Asia. But, Christ says, “if I went to them with the Teammachine R and said ‘I want this stiffness and this weight’ they would say ‘we cannot do it’. They know what they can do from what they did before. But if you want to push the boundaries, there’s no way other than showing them how they can do it. Then you sit down with them, you go through the ply book again, it is a lot of detailed work that usually is not visible.”
A single SLR frame contains around 300 individual layers, each placed manually. One layer takes about a minute. The full layup takes roughly five hours. “It’s still hand labour,” Christ says. “That’s why pushing the last percentage is never easy.”
Does he ever think there will be nothing left to push? “Honestly, I think the more you are looking for the last percentage, the more difficult it is. Of course you can always say you benefited from a previous project so you know it’s possible. And the manufacturing partner knows it’s possible, and you went through a certain method that was successful, so you have a good reference point. But you still have to do it.”
The new Teammachine SLR01 might be 16% lighter, aerodynamically sharper and just as stiff as before, but Christ already knows it won’t be the last word. “The gain is not always 16%, sometimes it’s only five. And sometimes you want to improve functionality. It’s not always about weight, aero and stiffness.”
And finally, after 19 years at BMC, does he ever feel as though he just can’t do another SLR01?
“No. Because it’s not just me. We are a whole team.”
And in the case of the new Teammachine SLR01, that team – and the Impec Lab that supports it – has yet again delivered results you can measure, ride and – most importantly – feel.
