This article was produced in collaboration with DT Swiss and was first published in Issue 139 of our magazine
A brand’s global reach is not normally measured in stainless steel spoke wire, but for DT Swiss there’s no better metric. The Biel-based company uses 40,000 kilometres of it every year – which is almost exactly the circumference of the earth. And the state-of-the-art machinery that produces 50,000 to 70,000 spokes per day in the Swiss facility has capacity to make even more. During the Covid boom of 2020 the factory made enough to go one-and-a-half times around the globe. “It was crazy,” remembers Peter Saegesser, DT Swiss’s head of production, his eyes widening in mock horror as he relives running two shifts concurrently, day and night, which he never thought he would have to do. Just once around the world is enough.
DT Swiss’s business is more than just spokes of course – it also makes hubs and rims and supplies entire wheels to major brands such as Canyon as an OEM (original equipment manufacturer) and is the wheel sponsor to the Tudor Pro Cycling and Uno-X pro teams. It makes suspension systems – forks, shocks and dropper posts. It has subsidiaries in Germany, France, Poland, Taiwan and the USA. DT Swiss is now considerably greater than the sum of its parts. But spokes is where it all started.
To be factually and historically correct, the company that became DT Swiss in 1994 started not with spokes but with wire, long before the advent of the bicycle. It can trace its origins right back to 1634, later joining with other wire producers to form Vereinigte Drahtwerke, or United Wireworks, and supplying wire in particular to the watchmaking industry during the 19th century. Biel is also Switzerland’s watchmaking capital, home to Omega, Swatch and Rolex, and the brands’ premises announce their presence in a unique way. Swatch’s HQ is a gigantic, 240-metre snake made from timber and glass and designed by Japanese architect Shigeru Ban, while Omega’s building is more traditional but perhaps even more surreal thanks to a full-scale lunar module standing in the courtyard in front. This commemorates the Omega Speedmaster, which Buzz Aldrin wore. You might make enough spokes to encircle the globe, it’s saying, but we put a watch on the Moon. What Swatch’s giant snake is saying is anybody’s guess.
DT Swiss’s corrugated metal HQ is less ostentatious, but there are many parallels that can be drawn between Swiss watches and DT Swiss wheels. Both demand the level of precision that Switzerland is stereotyped for – and both share the deep technical and cultural connections alongside the geographical ones. Both balance craftsmanship with cutting-edge R&D – it can’t be a coincidence that the ratchet rings inside a DT Swiss hub resemble a watch movement.
It wasn’t until 1934 that Vereinigte Drahtwerke started making bicycle spokes, and it was another 60 years before DT Swiss was formed. The name took the ‘D’ from Drahtwerke and the ‘T’ from Tréfileries – French for wireworks because Biel/Bienne is bilingual – after a management buyout of the spoke division. So it’s not surprising that the first port of call is not the hub museum on the first floor of the admin offices, but through some swing doors to the left of the reception and straight onto the noisy factory floor, where machines are cutting, cold-forging, hammering and stamping their way through huge coils of stainless steel wire, transforming it into the world’s best bicycle spokes.
“Let’s start with the raw material,” says Saegesser. He’s standing next to a group or ‘kanban’ of industrial-sized spools. “Here is our stainless steel wire from Europe – our suppliers are from Sweden and Germany. Each coil weighs 800 or 900 kilos. We have four different diameters of wire – the main one is 2mm, there’s 2.15mm for road ebikes, 2.34mm for freeride and downhill ebike, and the last [and least popular] is narrower, 1.8mm.”
Next we head over to a machine that’s making DT Swiss Champion spokes with 2mm wire. This is the brand’s entry-level, plain-gauge, classic J-bend model that’s the most straightforward to produce. A coil sits behind on a motorised rotating platform that pushes in the wire. “The wire starts bent in a circle on the coil so we have to get it straight,” explains Saegesser. There’s a pre-straightening phase, which puts multiple small bends into the wire as it passes through a series of closely spaced pulleys, and then the final straightening. “We use a lot of small bends because if you bend it too much or too fast you will break the material like a paperclip. The mechanical properties don’t change if you do it slowly.”
Next, the straightened wire is shot into the machine for precutting to within one millimetre of its final length and then is cut to its exact specified length. One end is then forced into a cone-shaped clamp that cold-forges the spoke head. “We have a measuring device, each head diameter is measured to a tolerance of 0.1mm,” says Saegesser. “If it detects a head that’s too small or too big the spoke falls out.” How often does that happen? “Among all of the spokes we produce, the rejection rate of our spoke production is less than one per thousand. And down the line the few rejected spokes will be recycled.”
The next arm or station of the machine puts in the J-bend, and another cold-forges the thread into it, pressing it in rather than cutting so that no material is removed and strength is increased. “Also the thread is controlled,” says Saegesser. “If it’s too thick or too small it’s rejected.” At the end of their short but eventful journey the finished spokes, each with a tiny DT logo stamped into its head, drop into a cardboard carton at a rate of at least one a second. There are 500 in each box – the machine counts them, moves the boxes into place, and away automatically once they’re full. Except they’re not quite finished. The majority – around 90% – of orders are for black rather than silver spokes. This particular consignment has the letter ‘S’ for ‘schwarz’ in its designation code printed on the piece of paper above the machine and will go to the other side of the factory for blackening in a 30-metre-long machine that applies a salt-based chemical treatment via a series of baths. Although it’s purely for aesthetics and does nothing for the spoke’s performance or durability it takes 40 minutes – a long time considering each silver Champion spoke is made out of the raw material in a matter of seconds.
For DT Swiss’s Aerolite, its lightest and most aerodynamic spoke, there are many more steps in the production process. The 2mm ‘blanks’ are butted so that the centre section is reduced to 1.5mm, making the finished spoke lighter. This process takes place in another machine where the spoke is subjected to rotating hammers, hitting it around 3,000 times per minute under cold oil to reduce heat build-up. “With hammering the material gets harder, denser, tensile strength goes up, and we need less material for the same length,” says Saegesser. The blading is done inside another machine: a yellow platform lowers itself metronomically onto each spoke that passes underneath, with a weight of up to 300 tonnes, increasing the material’s density yet further.
How much lighter is a butted, aero spoke compared with the plain-gauge spokes like the Champion? Saegesser says: “Same length, same head, same thread, between Champion and Aerolite it’s around 40%. But there are so many steps until you have that 40% less and that’s why the Aerolite is more expensive.”
Around 70% of all DT Swiss spokes are produced at the Biel plant including all the higher-end butted and aerodynamic spokes. The remainder are made by its subsidiaries in the US and Taiwan. “We produce only to order,” continues Saegesser, “we don’t produce anything for stock. So we wait until you order. That goes for everything, not just spokes. We produce some semi-finished products for stock but the finishing is always to order.”
DT Swiss’s other signature product, the star ratchet, which has driven its hubs since it acquired the Hügi patent in 1995, is also made in Biel. It starts with a steel bar instead of a coil of wire, 28mm in diameter for the 240 hub and 38mm for the 350 hub. The bars are fed into a CNC machine and are drilled, turned, milled and cut ready for the front teeth to be milled in a second machine that’s conjoined. Since it’s all done under jets of cooling oil behind the plastic casing, it’s impossible to see them taking shape. “If I turn off the oil the tools will get broken,” apologises Saegesser. It takes around two minutes to machine one star ratchet, but there are six steps in the whole production process of the star ratchets: the surface is hardened to a depth of 0.3mm, then multiple ratchets – about 5,000 at a time – are placed into an enormous tumbling machine and spun slowly in all directions for six hours, along with small ceramic stones that look like grains of rice. These slowly and evenly grind the sharp edges off. Under the lid it resembles a giant, abrasive risotto. Then the ratchet rings are lasered, coated, polished and packaged. It’s mind-boggling. “Yes, but in the end it’s industry,” shrugs Saegesser as we head back towards the swing doors and into the comparatively quiet, calm world of the reception. “Except we have a very good product.”
The wheel component that is conspicuous by its absence so far – in the factory at least – is the rim. Marketing manager Ralf Eggert explains: “For the aerodynamic development we have been working with aerodynamic experts Swiss Side for a decade. We ask them for a certain development and they work with it in CFD (computational fluid dynamics). We decide which rim profile we’re going to go with, which properties we want. Aerodynamics, handling, a balance between the two… We test a selection of 3D-printed shapes at the GST wind tunnel at Immenstaad. When we decide on the final shape that has been wind tunnel tested as a 3D-printed model, we hand it over to our engineers and they start to work on the construction of the rim. Then we have the first rim samples and the final iteration of the complete wheel and we go back to the wind tunnel to confirm that we’re on the right track.”
One of the most significant recent developments to come out of DT Swiss and Swiss Side’s partnership is the Continental 111 aero tyre, around which the third generation of ARC wheels, launched earlier this year, were designed. These were the first DT Swiss wheels to be designed with a tyre. Responding to the increase in average speeds of the pro peloton, says Eggert, “we went more back to a V-shaped rim profile, which is faster at lower yaw angles, but reduces the sailing effect in crosswinds. We knew it was a compromise, but when you use our specially developed aero tyre on the front wheel the sailing effect returns.”
The wheels are built at DT Swiss’s Poland subsidiary, each one fully by hand. However, there’s a crucial step before they go into production, and that’s where we’re headed next. All prototype, pre-production and small-batch series wheels, plus all the wheels for DT Swiss’s sponsored teams, are built in Biel by the BPM department (Biel Performance Manufacturing). Six people work here, and master wheelbuilder Michel Grémaud is in charge. Having worked in the watchmaking industry, like many of DT Swiss’s employees, he is both craftsman and data scientist. “We keep the wheelbuilding knowhow here in Switzerland and we guide serial production and training in wheel-building internally and externally. I also have a big network of dealers all around Europe who I taught to build wheels, so if I want somewhere to stay for free when I’m on holiday I know where to go,” he jokes.
“The wheelbuilding setup here is the same as in serial production, except we are six people in total and have two people truing instead of 50 or 60. We have a little bit more time to look at the product in detail, especially the prototypes. Nothing goes out of here that is not of the highest quality, so our quality control is quite special. We spend a lot of time examining the wheels that have come back from our Performance Test Centre after destruction testing.”
The Performance Test Centre, also inside the Biel HQ, is a lab packed full of machines designed to replicate as closely as possible the forces of outdoor riding. On one machine a weighted wheel runs on a drum over obstacles – the weight and the number and size of obstacles can be adjusted. On another, a hub is linked up to a burly motorcycle chain, which endlessly engages and disengages the ratchet teeth under load. A brake torque test analyses the connections between the spokes, hub and rim. There’s a burst test, where a tyre is inflated with ever-increasing water pressure (the final explosion is less noisy than with air) and another pulls spokes until they break. There are 25 tests and 20 or 30 wheels are tested per week. All prototypes are tested here to ensure they meet safety standards such as ISO and ETRTO and also DT Swiss’s own standards, which are much stricter, and competitor wheels are also tested here.
A recent graduate of the Performance Test Centre is DT Swiss’s first ever wheelset with carbon spokes, which will use the existing ARC 1100 carbon rim with a new 180 straight-pull spline hub. “Steel spokes are our heritage, but the market is also demanding carbon spokes,” says Eggert. As with all DT Swiss wheels, it was Grémaud and the BPM’s job to work out how to build the new wheel, which will be its lightest at under 1,200 grams, for ultimate quality, reliability and safety, and to hand over the process and the training for mass production. And he’s going to build one right now. “I can show you how it’s built step by step but the one thing I cannot show you is de-stressing.” For steel-spoked wheels DT Swiss uses a machine that braces the rim horizontally and then pushes the hub downwards so that the spokes seat correctly. This is done regularly during the wheelbuilding process. “If we don’t de-stress it, when you ride it for the first time it will settle, you’ll hear those pings and the wheel will go out of true. But, this machine can’t be used with carbon spokes because they don’t like pressure from the side. So we developed a secret process where we don’t push on the spokes and we don’t push on the hub either.”
Grémaud deftly inserts the carbon spokes through the hub and up into the holes in the rim, and the wheel takes shape. With the spokes all in and the nipples on, the wheel is clamped to the truing stand, where Grémaud uses a cordless screwdriver – which he apologises for because it’s technically a machine, and DT Swiss’s wheels are famously made completely by hand – to apply the initial tension to the spokes. He uses a tension meter and the gauges attached to the stand check what he refers to as the side-kick (lateral), bump (vertical) and middle (dish) and he would de-stress the wheel twice using the secret process as he does this. The tolerances are tight – 0.5mm – but Grémaud explains that the most important thing to teach the production wheelbuilders is even spoke tension. “It will be the lowest-tensioned spoke on the lower side that will damage your rim in the end. It has the biggest movement when you’re riding, doesn’t support the rim any more and on the other side you may have an extra strong one because this one is loose and that will break the spokes or deform the rim. So you need exact spoke tension.”
It takes around 40 minutes to build a wheel in the BPM and a little less in mass production. However, both use the same hardware, tools, and stands, so that the mass production process mirrors the BPM’s blueprint. Finally, the data for every wheel built is logged and stored, so that any production issues can be tracked back and affected serial numbers identified, going back to 2015.
There is a sense that with Grémaud at the truing stand you’re in safe hands. “Wheelbuilding is a passion for me,” he agrees. “If you do not love what you’re doing you will not achieve anything.”
DT Swiss’s chief technology officer Martin Walthert confirms this. “We stay ahead of our competitors first by passion, then by curiosity and by knowledge of what’s happening within the industry and outside it – new materials, new processes and new technologies. We are the experts – we engineer and manufacture everything ourselves and that gives us a huge advantage. We do not shout the loudest, we do not try to grab headlines for the sake of it and we will never beat others in price because we are a Swiss company. But the quality of our wheels is the best. Quality, honesty and above all safety are what we offer.” DT Swiss may not shout about it, but those values come through loud and clear in every millimetre of those 40,000 kilometres of spokes.
