Jumbo-Visma trials adjustable tyre pressure system at Dwars door Vlaanderen

Jumbo-Visma employed an adjustable tyre-pressure system on board some of their bikes at the men's Dwars door Vlaanderen on Wednesday, testing them ahead of Paris-Roubaix in a week and a half's time. 

A Gravaa KAPS (kinetic air pressure system) hubset system was spotted on the Cervelo S5 of Jumbo-Visma’s Edoardo Affini before the race got underway.

Pictures of the bike that were shared on social media before the race, clearly showed Affini’s new setup on his Cervelo S5. The bike was fitted with Reserve carbon wheel rims - as typically used by Jumbo-Visma - fitted onto Gravaa KAPS front and rear hubs.

According to Cyclingnews, the hubs feature an adjustable tyre pressure system using Bluetooth and Ant+ controls to allow the rider to adjust and control tyre pressures via a handlebar-mounted control unit.

This provides the likes of Affini, and eventual Dwars winner Christophe Laporte, with the ability to lower pressures for cobbles or rough terrain and then raise them again on smoother tarmac.

Gravaa is based in the Netherlands and their KAPS hubs house a small high-pressure, clutch controlled pump which is driven by the rotation of the wheel of the bike and controlled by an electronic printed circuit board (PCB). A bike's tyre pressure can then be controlled by a handlebar-mounted control system or on a smartphone app.

According to Cyclingnews, it appears the pump can inflate a tyre directly or from a buffer reservoir built into the hubs within seconds, a valve system also allows for rapid pressure decreases when needed.

Crucially for Jumbo-Visma, or any other professional team, the hubs do not create any extra drag and the pump rotates with the hubs themselves. The Gravaa system could provide a useful, and potentially critical advantage at the fast-approaching Paris-Roubaix, and could help the team combat power losses from resistance on the race's cobbled sectors.

In 2022, DSM suggested they would use a similar piece of equipment for Paris-Roubaix, the Scope Atmoz pressure management system. However, the team used their stock Shimano Dura-Ace groupsets instead. DSM also suggested that they may trial the system in the 2022 Tour de France, but opted against using it in competition full stop.

Gravaa has recently published some information on a Paris-Roubaix test that they’ve done. The company also shared information on wattage savings from using lower tyre pressures on the cobbled sectors.

Testing on the Camphin-en-Pévèle sector of cobbles the race passes over shows a 25 Watt saving at 35km/h between tyres when lowering pressure from 6 bar to 3 bar. And a 57 Watt saving when riding at 35km/h when decreasing pressure from 4.5 bar to 2.5/3 bar from test riders.

After Jumbo-Visma’s success with the new system this afternoon, perhaps we will see Wout van Aert riding a Cervelo S5 fitted with a Gravaa set up on the Roubaix cobbles in just over a week's time.