How it all started.
“I’m a fanatic cyclist!” laughs Gravaa CEO, Gertjan Van Ginderen, in answer to our question about how he would describe his feelings for two wheels. Today finds us in Gravaa’s HQ in Eindhoven to interview our fast founder about how he came up with the idea that tire pressure shouldn’t be static, but fluid, how he brought it to life, and, eventually, how it arrived on the wheels of some of the fastest cyclists in the world.
“Actually, everyone in this building is a fanatic,” he adds. “My first love was mountain biking, races, marathons and those sorts of things. I live in Zeeland, to the west of the Netherlands. In that area, we have a lot of beach races. We might say that beach racing is a typically Dutch pursuit, although it takes place in other countries, too. Anyway, in Zeeland we have a race called The Coast Marathon. It’s 54km of sand combined with stretches of asphalt that connect the islands of Zeeland. First there’s 14 km of sand, then 12km of asphalt, then back to the sand. You get the idea. Before I did the race, a colleague at the time advised me to ride with big balloon tires and to take co2 cartridges so I could stop to inflate my tires for the asphalt sections, and lower them by stopping once more to manually release the pressure when I arrived at a sand section. The reason of course is that sand and asphalt are almost perfect examples of surfaces that demand different tire pressures - very low for the soft sand, and high for the firm asphalt. Their requirements are so different that not stopping to change your tire pressure would almost guarantee a bad result.”
How it all started.
“I’m a fanatic cyclist!” laughs Gravaa CEO, Gertjan Van Ginderen, in answer to our question about how he would describe his feelings for two wheels. Today finds us in Gravaa’s HQ in Eindhoven to interview our fast founder about how he came up with the idea that tire pressure shouldn’t be static, but fluid, how he brought it to life, and, eventually, how it arrived on the wheels of some of the fastest cyclists in the world.
“Actually, everyone in this building is a fanatic,” he adds. “My first love was mountain biking, races, marathons and those sorts of things. I live in Zeeland, to the west of the Netherlands. In that area, we have a lot of beach races. We might say that beach racing is a typically Dutch pursuit, although it takes place in other countries, too. Anyway, in Zeeland we have a race called The Coast Marathon. It’s 54km of sand combined with stretches of asphalt that connect the islands of Zeeland. First there’s 14 km of sand, then 12km of asphalt, then back to the sand. You get the idea. Before I did the race, a colleague at the time advised me to ride with big balloon tires and to take co2 cartridges so I could stop to inflate my tires for the asphalt sections, and lower them by stopping once more to manually release the pressure when I arrived at a sand section. The reason of course is that sand and asphalt are almost perfect examples of surfaces that demand different tire pressures - very low for the soft sand, and high for the firm asphalt. Their requirements are so different that not stopping to change your tire pressure would almost guarantee a bad result.”
But pulling to a stop to change your tire pressure isn’t quick or easy at any time, and less so in a race environment. “Exactly,” agrees Gertjan. “In the heat of competition, stopping is stressful. Sometimes the cartridge wouldn’t work, it could be cold, so my fingers wouldn’t be as nimble. Many problems!” And presumably, not everyone stopped in the same place, or stopped at all? “Right again. So if I was in a group and we were riding well together, that became another difficulty. Because of all these challenges, I started wondering why I couldn’t change my tire pressure at will, on-demand, inflating or deflating it in response to changing surfaces, and all without stopping. In fact, while riding at speed.”
For most people, an idea like that might have intrigued them for a while, before getting quickly forgotten - an interesting concept but impractical. Not Gertjan. What was his first step? “All this was about ten years ago. At that time I was working as an advisor for real estate and building companies,” he explains. “I had a technical background, but nothing sufficient to the challenge of creating a concept like adaptable bike tire pressure. However, in the weeks following the race, I kept noticing how if I could only inflate the tires on my mountain bike - maybe with a handy button on the handlebar - and deflate them the same way, my riding would be so much more enjoyable. Once I saw it, I couldn’t imagine not having a system like that. So I started doing some internet research to see if the idea existed. It didn’t, although there was a product from the US that inflated the tires with a sort of exo-skeleton concept, but only until the on-board co2 lasted. My idea was to have the tire inflate endlessly via a pump in the hub. That was totally new.”
But pulling to a stop to change your tire pressure isn’t quick or easy at any time, and less so in a race environment. “Exactly,” agrees Gertjan. “In the heat of competition, stopping is stressful. Sometimes the cartridge wouldn’t work, it could be cold, so my fingers wouldn’t be as nimble. Many problems!” And presumably, not everyone stopped in the same place, or stopped at all? “Right again. So if I was in a group and we were riding well together, that became another difficulty. Because of all these challenges, I started wondering why I couldn’t change my tire pressure at will, on-demand, inflating or deflating it in response to changing surfaces, and all without stopping. In fact, while riding at speed.”
For most people, an idea like that might have intrigued them for a while, before getting quickly forgotten - an interesting concept but impractical. Not Gertjan. What was his first step? “All this was about ten years ago. At that time I was working as an advisor for real estate and building companies,” he explains. “I had a technical background, but nothing sufficient to the challenge of creating a concept like adaptable bike tire pressure. However, in the weeks following the race, I kept noticing how if I could only inflate the tires on my mountain bike - maybe with a handy button on the handlebar - and deflate them the same way, my riding would be so much more enjoyable. Once I saw it, I couldn’t imagine not having a system like that. So I started doing some internet research to see if the idea existed. It didn’t, although there was a product from the US that inflated the tires with a sort of exo-skeleton concept, but only until the on-board co2 lasted. My idea was to have the tire inflate endlessly via a pump in the hub. That was totally new.”
At that time, did he imagine the finished product, or at least have some redlines in mind in terms of design and compatibility? “Yes, indeed, he says. “My first requirement was that the system would give the rider the ability to inflate and deflate the tire endlessly, for as long as the wheel was turning. The second was that it should replace a bicycle pump.” Relying on sealant to plug any punctures, and his system to auto-inflate the tire back to a set pressure? “Exactly.”
It sounds magical, yet, here we are, ten years later and that is precisely what Gertjan and his team have created. “It’s been a long road,” he laughs. “I’m also proud that we were able to create a product that can work with any bicycle, with the hub at the center of what is an industry standard wheel doing the work of adapting the pressure. I didn’t want this innovation to mess with the bike’s silhouette, existing standards, take precious space, alter the drivetrain or whatever else. That was very, very important to me. The product we have today meets and even exceeds all of these requirements.”
Back before the Gravaa we know today, Gertjan was digging deeper, starting extensive patent searches, and making all of the many adjustments to his existing life which would be familiar to any entrepreneur impassioned by an idea they believe in. Then he started the really hard work: bringing a working concept to life. “To use a technical term, I wanted a de-centralised system, housed completely inside the hubs of the bicycle - self-contained, regenerating and self-powered. That would not be easy.”
So Gertjan reached out to development companies. “But by then, purely through practical knowledge of the bike and a good understanding of the basics, I went to them with a design,” he says. “I had all of the big blocks there, the architecture, like the clutch mechanism, pumps and electrical components, all of which form the Gravaa we know today, but packaged a lot smaller than I could ever imagine!”
The next big line in the sand came in 2016, when Gertjan connected with the technological hub of Eindhoven, now Gravaa’s home. “The technical university is here, and because of that hundreds, possibly thousands of technical companies that form an incredible eco-system of engineering and design talent.” What Gertjan needed was a mechatronics company, a technology specialist working at the cutting-edge of electronics, mechanical systems, pneumatics and more. “I found a company called Demcon. At the time they had 700 people, now they have several hundred, in multiple countries around the world. It’s an understatement to say they are immensely talented.”
Back before the Gravaa we know today, Gertjan was digging deeper, starting extensive patent searches, and making all of the many adjustments to his existing life which would be familiar to any entrepreneur impassioned by an idea they believe in. Then he started the really hard work: bringing a working concept to life. “To use a technical term, I wanted a de-centralised system, housed completely inside the hubs of the bicycle - self-contained, regenerating and self-powered. That would not be easy.”
So Gertjan reached out to development companies. “But by then, purely through practical knowledge of the bike and a good understanding of the basics, I went to them with a design,” he says. “I had all of the big blocks there, the architecture, like the clutch mechanism, pumps and electrical components, all of which form the Gravaa we know today, but packaged a lot smaller than I could ever imagine!”
The next big line in the sand came in 2016, when Gertjan connected with the technological hub of Eindhoven, now Gravaa’s home. “The technical university is here, and because of that hundreds, possibly thousands of technical companies that form an incredible eco-system of engineering and design talent.” What Gertjan needed was a mechatronics company, a technology specialist working at the cutting-edge of electronics, mechanical systems, pneumatics and more. “I found a company called Demcon. At the time they had 700 people, now they have several hundred, in multiple countries around the world. It’s an understatement to say they are immensely talented.”
Gertjan had hit upon an idea so intriguing, no engineer could turn it down. “Demcon were incredible. So generous with their time, so understanding, so keen to help that we made excellent progress together. After a year, we’d completed the feasibility phase and had a working concept - a desktop-system with a small pump, a membrane pump combined with a piston, the clutch and some standard electronics. And it worked! But of course, it was quite large. That was mid-2017.”
Would it be fair to say that the concept hasn’t changed since then - it just got smaller? “Correct. The principle is relatively simple. Gravaa is a hub-based system connected to the tire’s valve, pumping your tires up or deflating them on-demand via buttons on the handlebars, or even automatically, as Mariane Vos found recently when she suffered a puncture 3km from the finish line, before Gravaa kicked in, inflating her tires back to pressure so she could secure the win. Inside the hub there is a mechatronic device with a clutch mechanism, a pump mechanism, a printed circuit board and a valve mechanism, which steers the pressure through the system, to alternatively release pressure into the environment, or to the tire, as dictated by the clutch. It is the spinning of the wheel which powers Gravaa, so as long as the wheel is turning, it will operate. The speed of the pump is equivalent to the rotational speed of your wheel.”
As you’ll note from the pictures, Gravaa looks like a normal bike hub, albeit slightly larger than a standard one. As Gertjan explains, it is in fact a normal bike hub, just a massively tech-upgraded one. It’s self-contained, so it works with any bike and when it’s not doing anything it doesn’t add any friction whatsoever. There’s a module inside the front and bike hub, with the front hub acting as the master, and the rear the slave - the front wheel dictates the pressure for both. An antenna on the hub connects the wheels via bluetooth. “The only thing remaining are the controls, which consist of a ring shifter for a mountain bike, or if you have drop bars, a wireless module and small cable which pops into the end of one of the drops, and two buttons, one which sits on the right of your bars for increasing tire pressure and one on the left for decreasing it.”
There’s an app, too, which users can download from the Apple or Google stores and set up their user details which also registers and activates the warranty for Gravaa. The user can add details such as bike weight, riding style and so forth which will create a profile that includes suggested tire pressures. Once connected, these settings will automatically pass to Gravaa, which will kick in to maintain the predetermined pressure should their tires suffer a puncture and some pressure loss before their sealant can plug the hole. “The other way of using Gravaa,” notes Gertjan, “is to operate everything manually, using the handlebar controls to increase or decrease tire pressure at will. A lot of people do that.” Importantly, even under manual control, if the system detects a drop in pressure, it will kick in to pump the tires back to the pre-determined level.
And in case you’re worried about running tubeless, Gravaa works with tubes and tubeless systems. “It simply connects to the Presta valve on your wheel via a hose, so whether that connects to a tube or a tubeless tire doesn’t matter. It will work either way.”
But back to the development of Gravaa. “Following the concept with Demcon, we managed to attract investors and a European grant - this was in 2018,” says Gertjan. After that, it was a hard road of turning the working concept into a working model on the bike itself. The details are rather long and perhaps not so interesting to anyone outside of Gravaa, but suffice it to say, we managed to attract some of the engineers at Demcon who helped us bring the first concept to life, like Eugene, our Chief Engineer. After that, we had the challenge of prototyping, partnerships and production. Ultimately, we decided to make everything in-house. From start to finish, we now make Gravaa here - software, hardware, wheel development, the works.”
It’s now 2025 and an exciting time for Gravaa. “Yes, we just moved into this new building - a self-contained facility to assemble everything, including offices,” says Gertjan, the excitement visible on his face. “We make the whole system here in twelve assembly steps, from one hundred and forty unique parts, all designed and developed by ourselves. We made a deal with DT Swiss to use their hubshell and ratchet system and at the end, we have a finished product. So if you’re an existing bike wheel brand, you can integrate our system, and sell your wheel with a Gravaa upgrade. Or if you’re a bike brand, you can spec Gravaa with the wheels of your complete bike build. We’re also making our own complete wheels, but our first goal is to supply the industry.”
And in case you’re worried about running tubeless, Gravaa works with tubes and tubeless systems. “It simply connects to the Presta valve on your wheel via a hose, so whether that connects to a tube or a tubeless tire doesn’t matter. It will work either way.”
But back to the development of Gravaa. “Following the concept with Demcon, we managed to attract investors and a European grant - this was in 2018,” says Gertjan. After that, it was a hard road of turning the working concept into a working model on the bike itself. The details are rather long and perhaps not so interesting to anyone outside of Gravaa, but suffice it to say, we managed to attract some of the engineers at Demcon who helped us bring the first concept to life, like Eugene, our Chief Engineer. After that, we had the challenge of prototyping, partnerships and production. Ultimately, we decided to make everything in-house. From start to finish, we now make Gravaa here - software, hardware, wheel development, the works.”
It’s now 2025 and an exciting time for Gravaa. “Yes, we just moved into this new building - a self-contained facility to assemble everything, including offices,” says Gertjan, the excitement visible on his face. “We make the whole system here in twelve assembly steps, from one hundred and forty unique parts, all designed and developed by ourselves. We made a deal with DT Swiss to use their hubshell and ratchet system and at the end, we have a finished product. So if you’re an existing bike wheel brand, you can integrate our system, and sell your wheel with a Gravaa upgrade. Or if you’re a bike brand, you can spec Gravaa with the wheels of your complete bike build. We’re also making our own complete wheels, but our first goal is to supply the industry.”
One thing we haven’t spoken about is the first time Gertjan rode a bike with the Gravaa system. How did it feel? “It was incredible. Incredible. It’s been such a journey, that to finally ride the system as I imagined it and have it work better than I ever imagined, was the most amazing feeling.” In what way, better? “Performance - we totally underestimated the performance benefit of riding with adaptable tire pressure. We’ll have stats out soon to support this, but the results are pretty sensational. Simply put, with Gravaa, over a mixed-surface parcours, you will be much faster than without the system.”
It sounds like we should keep our eyes peeled for Gravaa out on the professional race courses of the world. “Absolutely. It’s going to be an interesting year ahead!”
Published on March 21, 2025
Words by: Pete Harrington
