Are Tour de France riders cornering on their tyre sidewalls? Prototype 29c Vittoria tyre suggests they might be

The Vittoria Corsa Pro is one of the best road bike tyres out there, and is seen fitted to a good few teams’ bikes at the Tour de France and throughout the season. For the majority of the season so far, the pros have been opting for a 28c width, pushing up to a 30c occasionally – especially for those nervous about hookless rim compatibility – and even 32c for races like Paris-Roubaix. But while at the Tour de France Grand Départ in Florence, we spotted some riders on team Visma – Lease a Bike using an unreleased 29c width of the Corsa Pro. 

Are pro riders so sensitive to tyre width that Vittoria felt the need to create a tyre that straddles the existing 28c and 30c options? Not quite.

Tyres have, on the whole, been getting wider as the seasons go by. Free from the constraints of rim brakes, manufacturers of both frames and wheels have been pushing the envelope and wheels are now regularly aero-optimised for 30c widths. Visma was seen running a new set of Reserve wheels at the Classics at the start of the year with a wider internal width, with claimed aero benefits for those races where wider rubber is called for. 

The sidewall of these new prototype tyres also states that they are optimised for a 25mm internal width rim, and when I asked Vittoria about it the brand confirmed our suspicions:

“Technically, it is an actual 29mm on a 25mm rim, optimised in terms of casing shape and tread width to improve puncture resistance and cornering safety when using 24-25mm rims, while maximising the aerodynamic benefit on such wide rims.”

It’s no surprise to hear there are claimed aero benefits, but the mention of ‘cornering safety’ is what has piqued the curiosity most in the Cyclingnews tech team.