The Vittoria Corsa Pro is without doubt one of the greatest street bike tyres on the market, and is seen fitted to a superb few groups’ bikes on the Tour de France and all through the season. For the vast majority of the season thus far, the professionals have been choosing a 28c width, pushing as much as a 30c often – particularly for these nervous about hookless rim compatibility – and even 32c for races like Paris-Roubaix. But whereas on the Tour de France Grand Départ in Florence, we noticed some riders on staff Visma – Lease a Bike utilizing an unreleased 29c width of the Corsa Pro.
Are professional riders so delicate to tyre width that Vittoria felt the necessity to create a tyre that straddles the present 28c and 30c choices? Not fairly.
Tyres have, on the entire, been getting wider because the seasons go by. Free from the constraints of rim brakes, producers of each frames and wheels have been pushing the envelope and wheels are actually frequently aero-optimised for 30c widths. Visma was seen working a brand new set of Reserve wheels on the Classics at first of the yr with a wider inside width, with claimed aero advantages for these races the place wider rubber is known as for.
The sidewall of those new prototype tyres additionally states that they’re optimised for a 25mm inside width rim, and once I requested Vittoria about it the model confirmed our suspicions:
“Technically, it’s an precise 29mm on a 25mm rim, optimised by way of casing form and tread width to enhance puncture resistance and cornering security when utilizing 24-25mm rims, whereas maximising the aerodynamic profit on such large rims.”
It’s no shock to listen to there are claimed aero advantages, however the point out of ‘cornering security’ is what has piqued the curiosity most within the Cyclingnews tech staff.
Two massive promoting factors of wider inside rim widths embody a much less curved lateral cross-section, which means a wider contact patch and thus higher stability in corners, in addition to a extra steady tyre sidewall beneath onerous cornering. As the sidewall is extra straight atop the wall of the rim it helps to cease it from folding over, however this push to wider rims, mixed with the continued use of 28c because the nominal normal width for execs has had an unintended consequence.
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For the identical tread width, in the event you widen the bottom of the tyre out, you additionally cut back the lean angle required to begin cornering on the sidewall of the tyre itself. The solely approach round that is to make use of a wider tyre, which then begins to negate the advantages of the extra sidewall help, in addition to including weight.
I think that this 29c width has, at the least partly, been developed by Vittoria on the request of Visma-Lease a Bike to allow their riders to nook tougher. I’ve put this idea to Vittoria, however I’m but to obtain a response.
There is already proof of this occurring with a really comparable setup. Alec Briggs of British staff Tekkers runs Reserve Wheels and Corsa Pro tyres and in a latest Instagram submit, it’s clear to see simply how far off the tread of the tyres he’s been going. One commenter asks “Rims too large for the tyre?”, to which the reply was a reasonably unequivocal “Yeah, principally”.
Expanding this thought out to UAE Team Emirates, we noticed Tadej Pogačar working 30c tyres within the opening levels of the Tour. It’s not clear whether or not he’s utilizing 30c for each stage, although. The Enve rims the staff makes use of are additionally wider than the norm, and it could possibly be that cornering potential is the rationale right here, too, quite than merely a case of aero optimisation.
Watching how onerous the Slovenian was driving on the descent of the Col du Galibier on stage 4, it’s actually not out of the query that it was on the forefront of the riders’ minds throughout recon rides.