This article was produced in collaboration with Gravaa and was published in Issue 139 of our magazine
In the final kilometre of the 2024 Gravel World Championships, after four hours of racing over dirt, tarmac and even cobbles in and around Leuven, two of the best Classics riders in women’s cycling are inseparable. Marianne Vos of the Netherlands, one of the greatest bike riders in history, is up against the home favourite Lotte Kopecky, who is hoping to claim her second rainbow jersey in the space of a week, having won the road title in Zurich only days earlier. The pair have tried to drop each other over all sorts of surfaces in the preceding 134 kilometres. But that’s all behind them and there are no more gravel sectors to navigate, only smooth tarmac up ahead, at the end of which lies the finish line and the chance for glory in the youngest of all World Championship disciplines.
Vos sitting behind Kopecky starts her sprint first, coming around the Belgian with a higher cadence. At first Kopecky seems to be able to match the Dutch rider’s pace, but she cannot quite get into her slipstream and Vos ekes out a gap and crosses the line with a comfortable lead. The victory added to Vos’s already legendary career, which includes World Championship wins in both road racing and cyclocross, an Olympic gold medal, Tour de France Femmes avec Zwift stages and a Monument title at Ronde van Vlaanderen. However, of her more than 250 professional wins, the 2024 gravel World Championships represented a first in Vos’s 20-year career – she rode using the Gravaa tyre pressure adjustment system. In the final stretch, from the comfort of her handlebars, Vos had inflated her tyres for the tarmac sprint finish. Gravel may be the new kid on the block in professional cycling, but you only have to look at the hype around the tech on show at races like Unbound to understand it is the discipline for experimentation, ingenuity and invention.
Twelve months on from Vos’s world title and 90 kilometres north-east across the Belgian-Dutch border, Gertjan van Ginderen jokes charmingly: “She won because of us!”
Van Ginderen, the founder of Gravaa, tells me that on that day in Leuven, Vos punctured with three kilometres to go to the line, but their system kept her tyres inflated in the final sprint.
There is a framed picture of Vos, celebrating as she crosses the line ahead of Kopecky, on the wall of Van Ginderen’s office at Gravaa’s headquarters in Eindhoven. Van Ginderen has every right to be giddy with excitement and pride. Vos’s triumph might be the crowning moment for Gravaa so far, but a rider winning a major title using the technology was a long time coming. Ten years ago he had the idea of a tyre pressure adjustment system which could be controlled in the cockpit. He was competing in a beach race in his home region of Zeeland, in the south-west of the Netherlands: “At first it’s on road, but only for a few hundred metres, and then it’s on the beach and after 20-25 kilometres, you end up at the Oosterscheldekering, which is the Delta works which is several kilometres long on asphalt – if you ride there on tyres at 0.5 bar (21.75 psi), it’s not really handy. So, that’s where the idea came from.”
What started as an inquisitive thought led to a decade of experimenting, developing and refining. Van Ginderen tells me: “I am a civil engineer, so nothing to do with electronics. In the Netherlands, some people say: ‘I have never done something before, so I think I can do it’.”
This fearless optimism, the no-nonsense and action-oriented mindset has seen Gravaa grow from a one-man team to over 15 full-time employees, with partnerships with commercial brands like wheel manufacturers DT Swiss and Reserve, and competitive teams like Vos’s Visma-Lease a Bike.
A physics lesson
The Gravaa system sits in the hubs of the wheels with a hose leading down a spoke to the valve. It is connected wirelessly to the rider’s cockpit and is controlled by buttons on the inside of the hoods of the handlebars, meaning you don’t need to take your hands off the bars as you enter bumpy, uneven or rough terrain. By pressing the button on the left of your bars, the pressure in your tyres goes up, and the button on the right makes it go down.
In the company’s workshop in Eindhoven, Van Ginderen talks me through the principles: “A compressor pump takes air from the atmosphere and lets out air into the atmosphere.”
This pump is one of 140 parts, most of which are sealed inside the hub, keeping out the mud and dirt that will be flicked up. Van Ginderen shows me the neat system, in which they have managed to compact the many elements: the clutch, electronics, the pump, with its pistons and an airtight membrane.
“The pump moves because of the rotation of the wheel, so you as the rider are pushing the pump, if it’s on,” he says. “So it’s your energy, which is only a few watts, that powers it. So the pump is engaged and the clutch comes in and the pump runs and once you’ve reached the set pressure point, the clutch comes out.”
When you want more pressure in your tyres you simply press the button, a camshaft in the hub stops spinning, the wheel’s continued rotation kickstarts the pump’s pistons, which sucks in air and guides it down a hose along the spoke to the valve. Four watts at 25kph is all that’s required, but this can be from freewheeling, as the wheels will still behut off when the desired pressure is reached.
“There’s a battery, which you need for your wireless communication because it runs on Bluetooth and Ant+ and to activate and deactivate t rotating. It takes roughly 100 metres of rolling along to pump up the tyre by 0.1 bar (1.45 psi), so 1.0 bar (14.5 psi) would take a kilometre.
To lower the pressure, there is a valve that opens to let air out. Sensors monitor the pressure in the tyre so this valve will automatically be she valves because they are solenoid, so they need a pulse to open and close,” explains Van Ginderen.
We walk through the workshop and meet employees who are tweaking parts, we see machines running tests and plenty of boxes and trays of components. Van Ginderen says: “We have developed everything ourselves. We’re producing everything ourselves. We’re assembling everything ourselves. All the plastic parts come from the Netherlands. All the metal parts come from an Asian supplier.”
Wireless communication and an app
Van Ginderen explains how the parts talk to each other: “We call the front wheel ‘the master’. The two wheels communicate with each other. So, every communication goes through the front wheel and then to the back wheel. And then you can see the display on your bike computer.”
Pre-set pressures can be made on the Gravaa app, which can be integrated on Garmin Connect, for example. This allows you to pre-determine the range and increments you want to adjust your tyre pressure for each ride.
“You can make your own pre-sets and you can also determine an offset between the front and rear wheel – for example, if you want 0.4 bar (5.8 psi) in the rear compared to the front,” says Van Ginderen. You don’t need to use the pre-set pressures either, you can just go up by increments of 0.05 bar (0.725 psi). It can go down to 1.5 bar (21.75 psi) and up to 5.5 bar (80 psi).
The whole system is remarkably subtle. Van Ginderen says: “Even if you take out the system and close the hub, you have a normal wheel. So, you can ride it without the system, it’s just a normal wheel. Serviceability is very important – having people back on the bike as soon as possible if something is wrong with your product, that’s key. You don’t want to be without your wheels for weeks.”
Not just for racing
Currently, Gravaa’s use seems most appropriate to elite cycling at gravel races and over the cobblestones of Paris-Roubaix. However, Van Ginderen himself is more of an adventure cyclist who enjoys long-distance bike packing trips with his son. He believes the Gravaa system has a place in this ever-expanding world within the sport. “I had a lot of punctures in the Belgian Ardennes on my mountain bike, like little punctures, where you can still ride for 10 minutes, and with our system you can completely deal with it.”
Compatibility with both gravel and road setups was important for Van Ginderen so that people don’t need to buy multiple wheelsets: “If you had 28-30mm tyres, our set-up goes up to 5.5 bars (80 psi) and that’s more than enough. The time we were pumping up to 95 psi is in the past.”
Obstacles and hurdles
Finding the right partners was a challenge in the early stages. However, towards the end of 2017, Van Ginderen says the company was able to show the idea could work in practice: “Feasibility meant we had a pump, we had a clutch and we had some basic electronics – a simple printed circuit board (PCB) with wireless communication to a desktop computer.”
This initial work, alongside a patent, meant the dream was becoming a reality, and Van Ginderen started looking for investors and subsidies.
“We went through all the prototype stages, from A, B, C upwards to C5 because we had to redo a lot. In the first instance we wanted to make a kind of air pressure reservoir in the rim.”
The prototypes and testing of different models eventually led to the system in the hub that is currently on the market. Van Ginderen says: “The story of Gravaa is a story of obstacles and hurdles. We wanted to outsource production, but the company that we were going to outsource it to went bankrupt. So, we took everything back under our own control and relocated here to Eindhoven.”
The Dutch city is home to several industry leaders, including Philips, the multinational health technology company, which was a former consumer electronics brand founded in Eindhoven in 1891. Although no longer based in Eindhoven, Van Ginderen believes the city is still “the hotspot of this kind of development”.
In parallel with Philips, Van Ginderen found the best engineers for Gravaa were from the medical world, those who have experience in designing breathing devices used in hospitals and ambulance services. “This kind of engineering has nothing to do with the standard engineering in the bike industry,” he says. “The background of our engineers is more from medical devices.”
The brand clearly has a product that people are interested in, and now Van Ginderen wants to double down on it: “We want to improve everything in terms of production for our product to be able to scale it up and to have a low as possible retail price. I heard somewhere that if you start a new development directly after your product launch, it means you don’t believe in your own product. And we believe in our own product and this is why we want to improve it.”
With the partnerships with DT Swiss and Reserve, Van Ginderen has more plans – which are at various stages of progress – to expand into the UK and North America: “We currently have about 20 authorised retailers in Europe. It’s growing and growing, we hope to have around 50 retailers next year.”
For Gravaa, despite Visma’s use at Roubaix, a race which Pauline Ferrand-Prévot won using the system, the biggest market is in gravel riding, which is an ever-expanding field in terms of participation and tech. Keeping up means brands have to be prepared to change with the times and Gravaa has proven it can adapt not only to the terrain but to each challenge, too.
Find out more details at gravaa.com
