PRO's wide body aero rim prototypes; 50mm pictured(Image credit: Matt Pacocha, Bikeradar.com)
Corsa Evo SC has a tread pattern reminiscent of Clement's storied Criterium(Image credit: Matt Pacocha, Bikeradar.com)
The herringbone tread pattern that seems to be so popular in the pro ranks(Image credit: Matt Pacocha, Bikeradar.com)
The tire uses a CoreSpun 320tpi casing(Image credit: Matt Pacocha, Bikeradar.com)
The new tire uses Vittoria's Iso Grip dual compound rubber, which is said to roll fast and grip well, however wear rather quickly(Image credit: Matt Pacocha, Bikeradar.com)
By its construction the PROtotype disc has a unique bulged shape(Image credit: Matt Pacocha, Bikeradar.com)
The disc part of the wheel is made up of two sheets of prepare carbon that are precisely cut to fit over the spokes, from hub to the trailing edge of the new, wide, 75mm rim(Image credit: Matt Pacocha, Bikeradar.com)
PRO's new PROtotype lenticular type disc is claimed ultralight and very stiff(Image credit: Matt Pacocha, Bikeradar.com)
Another peek inside the new disc(Image credit: Matt Pacocha, Bikeradar.com)
You can see the steel spokes within the PROtotype disc wheel by peeking through the valve hole(Image credit: Matt Pacocha, Bikeradar.com)
The 75mm model looks deep and fast(Image credit: Matt Pacocha, Bikeradar.com)
Rabobank is using the larger 23mm Evo SC tires for both road and time trial stages(Image credit: Matt Pacocha, Bikeradar.com)
Even though the new Vittoria Evo SC tire is 23mm the rims still sticks out beyond its profile(Image credit: Matt Pacocha, Bikeradar.com)
The new rims are laced to standard Dura-Ace 7900 hubs(Image credit: Matt Pacocha, Bikeradar.com)
PRO's wide body 75mm rim(Image credit: Matt Pacocha, Bikeradar.com)
The PRO require the larger tires because of their width, which is estimated at 25mm(Image credit: Matt Pacocha, Bikeradar.com)
Rabobank riders arrived at the Giro d'Italia time trial kick-off with three different types of carbon aero wheels – 50mm and 70mm deep aero options, plus a new time trial disc built with internal spokes - all conspicuously badged with giant "PROtotype" decals. Upon closer inspection, though, it turns out that the team was instead using wide-format Stinger carbon tubular rims from US company HED laced to Shimano hubs, all in the aim of reducing drag for more of a competitive edge.
The key feature of all three new wheels is their rims: all sport wide tire beds and brake tracks, which offer more support to the tire along with improved aerodynamics (because of better tire interface and blunt trailing rim edge). Rabobank mechanic Joost Hoetelmans estimated the new rims’ width at 25mm – in reality they're more like 28mm at their widest point.
Right now the team are primarily using the specially built wheels for time trials. All of the Rabobank riders started the first road stage on Shimano-branded 50mm and 35mm wheels. The two new road wheels sport straightforward builds, with 18 front spokes and, presumably, 24 rear spokes – rear wheels weren't available for our inspection.
The spokes are bladed and connect to the rim via standard external nipples. Both wheels rely on standard flanged Dura-Ace hubs. The wheels are Shimano-built and came to the team assembled. While seemingly pedestrian, the hubs sport Shimano’s much-loved angular contact bearings and ‘digital’ detented adjustment system, as well as a titanium cassette body.
The most interesting of the new trio is the disc, again based on HED's Stinger model. It’s built using the 70mm rim laced via standard spokes to the same, standard Dura-Ace rear hub as the road wheels. However, it’s then finished with a carbon cover that runs from the hub up to the rim, where it’s connected to roughly 1cm of the inner surface. This is done on both sides.
Hoetekmans said the design makes for an extremely light and stiff wheel. He didn’t have information on the build process or what rebuilding the wheel entails, although it clearly requires tire removal to access the rear of the nipples.
We weren’t able to weigh any of the new wheels on our scales, but swapping in the Shimano Dura-Ace hubs should only add a few grams to the stock HED versions, which weigh 1,339g for the 50mm wheels, 1,506g for the 70mm set, and 1,130 for the rear disc.
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PRO's new prototype lenticular type disc is said to be both ultralight and very stiff: pro's new prototype lenticular type disc is said to be both ultralight and very stiff
New rubber for Rabo’s wheels
Along with the new wheels, Rabobank were seen on an entirely new Vittoria Corsa Evo SC tire, with SC standing for Servizio Course or service course. Hoetekmans said the tire uses a tread similar to the storied Clement Criterium, but made from a new ISO dual (center and side) compound. This is said to offer the best grip in the line, as well as roll extremely fast. However, Vittoria admit it also wears fast.
The tread is hand glued to Vittoria’s natural colored CoreSpun 320tpi casing, in a 23mm width rather than the 21mm traditionally used for all-round road race stages. The CoreSpun casing threads have a poly core that’s wound in cotton to remain suppler than a solely synthetic casing. The tire is currently only available in a 23mm width. Claimed weight is 250g.
The team were using the new tire in a larger width on the rear disc wheels for the opening time trial, as it fits the wider rim, both in terms of handling and aerodynamic performance, much better than a smaller tire.
