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.”
