Pictures of the bike shared on Twitter (opens in new tab) before the race show the Cervelo S5 fitted with Reserve carbon wheel rims (as usually used by the team) laced onto Gravaa KAPS front and rear hubs. These 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 gives riders the ability to lower pressures for cobbles or rough ground and raise them again on smoother tarmac. Cyclingnews was unable to find prices for the hubset alone but the GRAVAA R-40|44 road wheelset is priced at €4,299.
Gravaa (opens in new tab) 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 print circuit board (PCB). Tyre pressure can then be controlled by a handlebar-mounted control or an app. 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 a professional team, the hubs do not create any extra drag and the pump rotates with the hubs themselves. The system could provide a useful and potentially critical advantage at Paris-Roubaix, in particular, and could combat power losses from rolling resistance on the race’s cobbles.
👀 Looks like Affini is testing the KAPS adjustable air pressure system. #DDV23 #DDV pic.twitter.com/myK3cltMrFMarch 29, 2023
Team DSM previously suggested they would use the Scope Atmoz ‘pressure management’ system ahead of the 2022 Paris-Roubaix. However, the team opted to use their stock Shimano Dura-Ace wheelsets for the race instead. The £,3000 wheelsets haven’t seen competitive use from the team but they did recently claim the technology is an ‘ongoing project’.
Like the KAPS hubs, the Scope system also claims to add no extra resistance and uses wireless handlebar-mounted controls. So on paper, at least, the systems do seem similar.
Gravaa has published some information on a Paris-Roubaix test they have done and the claimed wattage savings from using lower pressures on cobblestone sections are certainly not to be sniffed at. 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.
In today’s peloton, where small single-digit wattage savings are highly valued, the potentially huge wattage savings claimed could represent the difference between winning and losing the race. Teams seem to certainly be aware of the potential savings and advantage, perhaps we can expect to see a tyre inflation system blooded on the Roubaix cobbles this year if these race testing results are favourable.