To tour Paris-Roubaix, each cyclist needs two bicycles: one to cover the asphalt for 200 kilometers and another to dock on cobblestones for 54.5 kilometers.
The first of 29 cobbled sections comes after 96km on Sunday, with around 160km to go. You would say: switch from asphalt to cobblestone bike after about 90 kilometers. But that doesn’t work because of the nervousness and tension in the peloton when everyone wants to sit at the front as soon as they pass a northern French farm road for the first time.
They are terrible roads, with jumbled boulders varying in size, sharpness, height and spacing, very slippery when wet.
It is completely unthinkable to change bikes after every bounce. In other words: if you can’t change bikes along the way, change something on your bike along the way. That? Tire pressure.
pump without getting off
Of the two Dutch cycling teams, Team DSM will definitely give it a try and Jumbo-Visma can give it a try on Sunday: riding a bike with a device to inflate the tires for asphalt without getting off or to let out some air when the cobblestones show up. Jumbo-Visma and DSM each use different systems, costing around 4,000 euros, approved by the UCI international cycling federation from two Eindhoven-based companies. But the idea is the same.
Around or on the axis of the front and rear wheel there is a mechanism with, along the spokes, a tube to the valve. Buttons on the steering wheel send a wireless signal to both wheel axles to get more or less air into the tires. The cyclist can read the current tire pressure on his cycle computer.
About the Author
Robert Giebels is a sports reporter who writes about cycling and Formula 1. He previously worked in political writing and as an Asia correspondent.
The added weight of, say, a full water bottle far outweighs the benefits of riding your bike with the right tire pressure for the right surface. Pedaling on perfect asphalt on ‘soft’ tires costs an unnecessary amount of energy and can also be dangerous in corners.
On the other hand, Gianni Moscon knows what it’s like to step on cobblestones with tires that are too ‘hard’, since the 2021 edition of the ‘Roubaix’. Until he got a flat tire and bought a new bike with too high a tire pressure. Unsure, Moscon then bounced in all directions. He soon fell and was fourth.
Going over cobblestones with the proper tire pressure ensures that the tires maintain much more contact with the surface. That has several advantages. There’s more grip, as Moscon demonstrated. There’s more cushioning, which means less hand and shoulder pounding, though all the drivers are still utterly nervous, especially on the most gruesome stage of all: the Trouée d’Arenberg, better known as the Forest of Wallers.
The biggest advantage of ‘soft’ tires on cobblestones is that the rider has to deliver less power at the same speed. At least, that’s what manufacturers of seated tire pressure systems promise. The tire is propelled by the ground, not the air. Staying in contact with the cobblestones is more energy efficient than turning it on again and again after the tire has been thrown off a cobblestone.
The chosen tire pressure is a necessary compromise between asphalt and cobblestones at Paris-Roubaix. The cyclist, therefore, sacrifices himself on both surfaces, but especially on the almost 55 kilometers of boulders. Roughly speaking, it takes twice as much force in those sections to keep pedaling at 30 kilometers per hour with the same tire pressure. If it is much lower, the energy savings on the paving stones for the cyclist can reach 10 percent.
DSM was supposed to race Paris-Roubaix with the tire pressure system last year, but after some experimentation, the riders still weren’t sure. The steering feels different with a heavier front wheel. The ‘Roubaix stage’, the fifth stage of last year’s Tour, also came too soon. This year DSM expects a trick from frontman John Degenkolb, ‘Roubaix winner’ in 2015.
In Jumbo-Visma, Italian Edoardo Affini drove the cobbled Flemish classic Dwars Gate Vlaanderen with the tire pressure system last week and was pleased. His teammate, Dutch Paris-Roubaix winner Dylan van Baarle last year, reportedly tested the system extensively in training and is said to be very enthusiastic about it.
Not that he immediately considers himself likely to succeed himself on Sunday. Due to a fall and illness, Van Baarle has regressed a bit and he doesn’t know how good he is compared to the two Sunday favourites: Mathieu van der Poel and Wout van Aert. Whether the Jumbo-Visma leader will push innovation, he declined to tell Belgium’s Sporza on Thursday. “You’ll see on Sunday. It has a lot of future, but of course it has to work perfectly.’