In the ever-evolving world of WorldTour bike tech, equipment trends can shift as quickly as the peloton itself.
One such trend, which has been a topic of particular interest this week here at Cyclingnews, is the move towards wider tyres. Our latest lab test proved that for most riders, 40mm tyres are faster, and that on cobbled surfaces there's a potential benefit of over 70 watts.
The full details are available to Cyclingnews subscribers, and one of the WorldTour's biggest names has weighed in with his thoughts.
Speaking ahead of Milan-San Remo, we asked Mathieu van der Poel about the results of our test, and he acknowledged he's been slow to follow the trend.
"Last year, I was one of the only riders to still ride 28 millimetres, just because I kind of liked them," the Dutchman began.
"The team was already riding 30 millimetres last year, so for sure it's a trend. The big advantage with bigger tyres is that you can use a lower tyre pressure, and that, of course, makes a big difference on the cobbles.
"There's a big chance I will ride 30 millimetres this year in the Classics races."
The Cyclingnews test pitted tyres from Pirelli's P Zero TLR lineup, from sizes 26mm right up to 40mm, against each other across two wheelsets, two surface types, two speeds, and seven yaw angles in a test that compared the potential rolling resistance benefit against the aerodynamic detriment.
The worst-case to best-case difference was a saving of over 70 watts, but even between an already-common 32mm tyre and a currently-rare 40mm tyre on the same rim, there were over 25 watts on the table on cobbled surfaces.
By coincidence, Van der Poel's Alpecin-Deceunick team switched to Pirelli tyres at the start of the 2025 season, so he does have the 40mm tyre available to him, should he want them.
But even with the cobbles of Paris-Roubaix looming on the horizon, there's a very good reason why he won't use them.
The Dutchman's preferred race bike - the Canyon Aeroad CFR - doesn't have clearance enough to fit them. To take advantage of the 40mm rubber, he'd have to switch to a different bike, and given the Aeroad CFR is Canyon's most aero option, anything else would be less aerodynamic overall.
The Cyclingnews lab test did compare the aerodynamic penalty of the wider tyre when doing the calculations, but it controlled for the bike using a Cube gravel bike as the test mule. For Van der Poel – and indeed most of the WorldTour peloton – to use 40mm tyres, he'd not only have to factor in the aerodynamic penalty of the bigger tyre, but also the different frame, cockpit and so on. Potentially even a different riding position too.
Notably, Israel Premier-Tech made the bold decision to use the Factor Ostro Gravel bike at last year's Paris-Roubaix, a bike which would clear 40mm tyres with ease, but given anything wider than 32mm tyres fouled the back side of their Shimano front derailleur, they missed out on a potentially sizeable gain.
If they threw caution to the wind and switched to a 1x groupset and appropriate wheels, the data suggests 46 watts could have been saved.
Van der Poel is rightly cautious about the real-world benefits, though. Even at Paris-Roubaix, there are over 100 miles of smooth roads to contend with around the cobbled sectors, and there, at the speeds the professional peloton rides at, the aerodynamic benefit could quickly offset the rolling resistance improvement, assuming of course that the Dutchman has his nose in the wind and isn't safely ensconced in the peloton.
Whether the net difference over the entire course would be positive or negative is unknown, and largely dependent on how a rider chooses to race.
"The difference is not so big," Van der Poel continued. "But if you compare it to a 23-millimetre tyre, then there's an enormous difference. I wonder where it's going to stop. You see already riders using 35mm tyres in Roubaix, which is really wide.
"I think there's also a limit to it. After a while, if you go any bigger, you won't be faster anymore."
The Dutchman's opinion shines something of a light on his mindset when it comes to tech, marginal gains and equipment optimisation.
While some riders are early adopters, such as Victor Campenaerts' use of the Classified hub, Tadej Pogačar's use of carbon chainrings, and Primoz Roglic's use of a gravel groupset, Van der Poel appears happy to use what he's given, and what he's used to.
You can't say it isn't working for him though. The Dutchman soloed to his second successive Paris-Roubaix win in historic fashion in 2024. He broke away alone with 60km to go, finishing a full three minutes up on his teammate Jasper Philipsen in second place, setting a record average speed in the process.
His palmares is one of the best in the sport's history, too, and he shows no sign of slowing down.
