Just In: Mavic Cosmic Pro Carbon SL C wheels

Mavic’s new Cosmic Pro Carbon SL C clincher wheels have just arrived for review here at road.cc with all-carbon rims, an updated aerodynamic profile, and a laser treatment that’s designed to offer the best wet weather braking performance out there. 

The Cosmic Pro Carbon SL C (£1,450 for the complete wheelset), like the new Ksyrium Pro Carbon SL-C (£1,500), features all-carbon rims. 

Previously, Mavic used aluminium rim beds in its carbon clinchers for safety reasons – to dissipate heat that can rise to 200°C during braking – but the French brand believes that it has developed a manufacturing process that allows it to dispense with the metal. 

Mavic says that it can now produce one-piece carbon rims that are consistent enough that they need no extra machining, which would weaken the structure, when they come out of the mould. 

It has also developed a proprietary heat treatment protocol that increases the ability of the rim to cope with the high temperatures associated with prolonged braking. All of that means the aluminium insert is no longer necessary.

Mavic calls its new technology iTgMax.

“iTgMAX consists of an inner rim bed finished with multiple layers of seamless carbon fibre to achieve a unique one-piece rim contour without cutting any fibres,” says Mavic. “The brake track is then finished with a laser machining to ensure the best braking efficiency.”

This removes the resin from the surface while leaving the carbon fibre intact.

Mavic claims that this results in consistent and efficient braking with stopping distances in wet conditions 50% shorter than Zipp Firestrike and Firecrest wheels, for example. 

We’re interested in trying this out because even the most ardent of fans would have to admit the braking performance of carbon wheels has lagged well behind that of aluminium, especially when it rains.

Go to our wheels review archive.

Like most (but not all) of Mavic’s existing Cosmic wheels, the Cosmic Pro Carbon SL Cs have 40mm deep rims, but these are a new rounded shape based on a NACA profile. NACA is an abbreviation that gets bandied about a lot when it comes to bike aerodynamics these days. It stands for National Advisory Committee for Aeronautics, a US agency founded to undertake and promote aeronautical research, and which developed many airfoil shapes.

The Cosmic Pro Carbon SL Cs have fairly wide rims. The external width is 25mm while the internal width is 17mm. That’s not as wide as Zipp’s 303 Firecrest Carbon Clincher, for example (26.4mm across the brake track, 28.5mm maximum) but it’s not far off. The idea is to integrate well with the wider tyres that most people are using now. Mavic recommends tyre widths from 25mm to 32mm with these wheels, more evidence that 23mm tyres are very much on the wane.

Speaking of tyres, the wheels are fitted with Mavic’s own YKsion Pro GripLink (front) and PowerLink (rear) tyres in a 25mm width. The GripLink has a Kevlar breaker to help avoid punctures while the PowerLink has something similar in polyamide.

Check out our complete guide to Mavic road wheels here.

The wheels also incorporate the Instant Drive 360 freewheel system (Shimano/SRAM and Campagnolo options are available) that Mavic introduced last year. The design features a 40-tooth dual ratchet system that provides engagement in 9°. In other words, you start to drive the rear wheel almost immediately on resuming pedalling after coasting.

The bladed spokes (18 front, 24 rear) are straight pull and double butted.

The Mavic Cosmic Pro Carbon SL C clinchers weigh 1,450g and they’re priced at £1,450 – so you’re paying a pound for a gram, if you want to look at it that way. The rims are a claimed 450g each.

The Cosmic Pro Carbon SL is also available for use with disc brakes. The tubular version is £1,650 while the clincher model is £1,500.

www.mavic.co.uk