The primary challenge with carbon clinchers has always been heat management. Under hard or prolonged braking, temperatures can soar well above 400ºF, enough to potentially soften the resin in the sidewalls. With 100+ psi pushing against the sidewalls, that could mean anything from rim deformation (ruined rim) to a complete blowout (ruined you). It’s one of the reasons so much attention is paid to resin formulation, pad compounds and the like.
All the major players have addressed this in their own way in order to provide riders with a full carbon clincher. The notable exceptions were Mavic and American Classic, which have kept their all-carbon rims limited to tubular options. Until now.
The new Mavic Cosmic Carbone 40 Clincher uses a new construction process to provide a quasi-full carbon clincher. But, with wheelset weights almost identical to the slightly deeper (and Exalith-tracked) Cosmic Carbone SLR and still above full carbon clinchers from, say, ENVE, what makes them special?
From a lineup standpoint, it fills the small gap between their 30mm deep Cosmic Elite and the 52mm Cosmic Carbone wheels. It also becomes their second wheelset to use a rounded NACA airfoil shape, following the recently introduced Cosmic CXR 80 and shaped in the Geneva wind tunnel to excel in a broad range of wind angles. But, none of that answers the question: What makes them special?
“It’s just different,” says Mavic’s PR rep Zack Vestal. “The rim itself is quite light, much lighter than the CC SLR, and because it doesn’t require a rim strip, it’s ultimately lighter than competing wheels that do have a drilled rim bed. So, you get better aerodynamics thanks to the rounded profile and super low inertia with no compromise in stiffness. We feel all of this makes the ride characteristics better than anything else out there.”
Key features of the new wheelset include:
- Aluminum spoke bed insertions are threaded with Mavic’s proprietary FORE process, eliminating the need to reinforce the outer carbon section while evenly distributing the spoke tension load. This also means easier service.
- Lightweight one-piece aluminum tire bed and bead hook insert offers enhanced structural resistance to tire air pressure and brake heat buildup while also creating a precise, ERTRO-compliant bead hook.
- New TgMAX dual resin technology uses 2 types of resin, each with its own glass transition temperature [Tg], plus a specific heat treatment/molding process to increase the Tg of the entire system.
There’s also a special surface treatment on the brake track to improve braking efficiency in both wet and dry conditions.
“We developed a complex surface treatment process which enables us to achieve braking distances which are half the braking distances of current carbon wheels,” said Michel Davoine, Mavic Development Engineering Manager. “All these processes that we developed to obtain this high performance rim took a lot of time. Development lasted more than three years with a full team of engineers,” added Davoine.
Vestal says it’s a process they’re keeping close to the chest, but that “it feels coarse, almost raw, but also super hard. It’s a little bit abrasive. I think you’ll see a little faster brake pad wear than with other wheels, but the brake bite is pretty shocking. They stop really well. It’s also extremely tough and wear resistant, it should last longer than alloy rims. Plus, these won’t get the glaze or debris coating that alloy rims can.”
The nice thing is they’re recommending commonly available SwissStop Yellow pads, which are included with the wheels.
Another unique feature is the foam core. Vestal says this is to ensure precision placement of the alloy parts and the carbon layup during assembly. “When you assemble the aluminum tire and spoke bed inserts, the foam ensures good tolerances from the top to the spoke bed, which lets them do thinner sidewalls. That means less material, which means less weight. It’s pretty firm, but super light.”
Put it all together and you have a lightweight package that has “added radial impact resistance thanks to the isotropic nature of aluminum” with an aero profile designed to work as well in crosswinds and straight on.
- 1545g (670g front/875g rear)
- 2085g for complete Wheel-Tire System.
- 40mm deep profile carbon rim
- Carbon hub shells with aerodynamic aluminum flanges; QRM+ adjustable preload bearings; aluminum axles
- Bladed/butted stainless steel spokes with external, integrated alloy nipples
- 16 radially laced in front; 20 laced radially non-drive/ 1-cross drive
- Includes GripLink clincher front / PowerLink clincher rear tires
- USA Price: $2,750
- USA Availability: June 1
- Includes brake pads, skewers, hub tool, wheel bags, tires and tubes
External rim width at the brake track is 19mm, which is admittedly narrower than what’s trending. But, Vestal says they were going for lightweight and that added width didn’t add anything to the performance that they didn’t feel they were already getting.
The included Yksion GripLink front and PowerLink rear tires weigh 190g each. They are 120tpi 700x23c, but Mavic admits they run a bit narrow even though the inside air volume runs pretty close to a true 23. They’re a dual compound with softer rubber on the shoulders, and a generally harder mix on the rear tire. We’ve ridden them and they’re pretty darn nice.
And, yes, we asked about running them Road Tubeless: “It’s an airtight tire bed, but we don’t have a valve that would fit. Officially, no, and we wouldn’t recommend it but people have found ways to do it. At the moment, Mavic is not working on road tubeless.”
And now for our feature presentation…