Mavic have never had a carbon clincher wheelset in their range, at least not until the Cosmic Carbone 40C was launched earlier this year with the claim that it is “the first reliable carbon clincher wheel”.
It’s a segment of the wheel market plagued in the past by reliability issues. While aluminium dissipates heat, carbon fibre accumulates heat under braking and a rim can reach temperatures of more than 200c. That can result in an inner tube blowout, or worse, the rim can reach ‘glass transition’, whereby the resin essentially melts and the rim fails.
Carbon fibre brake tracks also offer poorer braking compared to a machined aluminium rim, particularly in the wet, when the pads are typically required to initially wipe water off the rim before any significant stopping power is offered.
However, Mavic claim they have solved both issues with the Cosmic Carbon 40C wheelset, which has been three years in development and has now arrived at RoadCyclingUK for review.
Heat dissipation and braking aside, what carbon clinchers do offer over a low-profile aluminium rim, or a carbon/aluminium hybrid, is improved aerodynamics as the rim can be extruded to a greater depth than an all-aluminium rim, and moulded as one piece to fine-tune aerodynamics.
First, the headline numbers. The wheels weigh 1,545g for the pair, or 2,085g when fitted with Mavic’s Yksion Pro Griplink and Powerlink tyres on the front and rear, which, along with inner tubes, quick release skewers and wheel bags, are included in the £1,800 package.
So, how have Mavic produced a wheelset which they say offers “the best combination of reliability and light weight for the most versatile aero wheelset”?
On the face of it, the Cosmic Carbone 40C is a full-carbon wheelset but, look beneath the surface and it remains a hybrid, just not a hybrid we’ve become accustomed to elsewhere in the Cosmic Carbone range, whose hoops traditionally have an aluminium braking track and carbon fairing.
Instead, the Cosmic Carbone 40C uses a lightweight aluminium rim bed insert (which in itself wouldn’t be strong enough to build a complete aluminium rim), which forms the rim bed and tyre bead hooks, and is therefore designed to dissipate heat while maintaining the structural integrity of the rest of the wheel. A foam core is used beneath the insert, and above the inner edge of the rim, as it is light, strong and heat resistant. The core and aluminium insert are then wrapped in carbon fibre.
It’s also worth pointing out that the aluminium insert is undrilled, so there’s no need for rim tape, and Mavic also say that improves the strength of the rim. The bladed spokes (16 front, 20 rear) thread into aluminium inserts on the inner edge of the rim, just beneath the foam core. The hubs have alloy flanges and a carbon fibre shell, and the freehub body is 11-speed compatible, with a spacer provided to use with a 10-speed cassette.
As for the braking track, Mavic have applied a proprietary TgMax treatment, which essentially uses two types of resin, each with its own glass transition temperature, to manage heat dissipation and also improve braking efficiency. It’s a similar technology to that used by competitors, including Reynolds and their CTg treatment. However, Mavic say they’ve also been able to reduce braking distance in wet conditions by 50 per cent compared to rival carbon clinchers. The video below runs through the manufacturing process in more detail.
The Mavic Cosmic Carbone 40C wheelset comes with some bold claims for heat dissipation and improved braking. Mavic have reached those conclusions following extensive field and lab testing. Field testing was designed to simulate the worst case scenario, using a 10km section of the descent off Mont Ventoux, riding at a consistently high speed while constantly applying the brakes with a 100kg rider.
A claimed weight of 1,545g doesn’t make the Cosmic Carbone 40C wheelset particularly light for the outlay – carbon clinchers usually come with a weight penalty over tubular variants – but Mavic are packaging the CC40C’s as a versatile aero wheelset, for sportive and gran fondo riders who want a combination of reasonable weight, aerodynamics, stiffness and, above all, reliability.
We’ve already spent some time on the wheels, slotting them into the Canyon Ultimate CFX currently on test for the Etape du Tour, and will log more miles to see whether Mavic’s claims stand true. Watch out for a full review.