Gear News

Mavic launch new Cosmic Pro Carbon SL C and Ksyrium Pro Carbon SL C wheelsets: full carbon, more aero, better braking

French firm overhauls carbon clincher range

Mavic have launched two new full carbon clinchers: the Ksyrium Pro Carbon SL C and Cosmic Pro Carbon SL C. In doing so, Mavic have dropped the aluminium insert previously found in old carbon clincher models, while also introducing an updated aero profile and a patented laser treatment technique to offer ‘industry leading’ wet weather braking performance.

A quick history lesson: Mavic unveiled their first carbon clincher wheelset, the Cosmic Carbone 40 C, in 2013 – except it wasn’t a full carbon clincher but a hybrid, as Mavic used an aluminium insert within the rim to help dissipate heat. Mavic called the Cosmic Carbone 40 C “the first reliable carbon clincher” as a result and the Ksyrium Pro Carbon SL followed in 2015, but again it used an aluminium rim bed.

– Mavic Cosmic Pro Carbon SL and Ksyrium Pro Carbon SL wheelsets – first ride review –

Now Mavic have gone all in on carbon clinchers – switching to a full carbon rim, updating the 25mm-deep Ksyrium Pro Carbon SL C and introducing the 40mm-deep Cosmic Pro Carbon SL C. If you’re not familiar, Mavic’s Cosmic and Ksyrium ranges cover a number of wheelsets, with the Cosmic line being pitched as ‘fast and light’, combining low weight and aerodynamics, while the Ksyrium line of ‘endurance road wheels’ are designed to marry durability, reliability and performance.

There are also new disc-specific and tubular versions of both the Ksyrium Pro Carbon SL C and Cosmic Pro Carbon SL C on the way – but nothing tubeless. That said, the key news here is the carbon clinchers, so here are the headline features from the launch in Nice, France, before we get into more detail – or if you want to skip to our first ride review, then just head this way.

  • Improved carbon tech prompts switch to full carbon rim
  • Seamless 17mm-wide carbon rim bed optimised for 25mm tyres
  • New Cosmic aero rim profile claimed to be faster than Zipp
  • Laser treatment technique to improve wet weather braking
  • Weights: 1,450g for Cosmic Pro Carbon SL, 1,390g for Ksyrium Pro Carbon SL
  • Pricing: £1,450 for Cosmic Pro Carbon SL, £1,500 for Ksyrium Pro Carbon SL
  • Disc and tubular versions also available
Mavic have launched revamped versions of both the Ksyrium Pro Carbon SL, pictured here, and the 40mm-Cosmic Pro Carbon SL wheelsets (Pic: Ashley Quinlan/Factory Media)

Mavic switch to full carbon clincher rim

The new Cosmic Pro Carbon SL C and Cosmic Pro Carbon SL C wheelsets feature technology that represents a step forward for the French firm, due to the improved resilience of the carbon layup, and has allowed Mavic to switch to a full carbon rim. Previously, Mavic used an aluminium insert in the rim bed in order to help dissipate heat and to address safety concerns surrounding the performance of a carbon clincher rim under heavy and prolonged braking.

The change has been made possible thanks to new techniques developed by Mavic in moulding the carbon layers into a single, seamless piece so that the aluminium insert is now no longer required.

“Instead of using aluminium to fight high temperatures under extreme braking and protect the rim – something we used in our first generation of carbon clincher wheels – we’ve now developed a new way of moulding the carbon in a single piece,” says Maxime Brunand, Product Line Manager for Mavic.

“The single piece construction, developed with our proprietary curing process, maximises the melting point of the resin used to glue the carbon fibre layers together. This makes the wheel more resilient to the heat of braking [up to 200 degrees celcius under extreme conditions], and takes away the need to machine the wheels, which results in weaknesses in the product.”

Losing the aluminium insert also drops the weight of the rim, now a claimed 450g for the Cosmic and 400g for the Ksyrium, and that reduced inertia should improve the responsiveness and handling across both wheelsets. The claimed weight for both wheelsets is suitably low, at 1,450g for the Cosmic Pro Carbon SL C and 1,390g for the Ksyrium Pro Carbon SL C.

The Ksyrium has a 25mm-deep rim, while the Cosmic, pictured here, is 40mm. Both have an aero profile

Wider rim for wider tyres

Both the Ksyrium and Cosmic rims have a 17mm internal width and are 25mm wide at the brake track, and Mavic say this optimally supports a 25mm tyre, which has become the standard across the industry over the past couple of years, and the width of rubber specced on these wheels.

Speaking of which, Mavic sell their wheels as a complete Wheel Tyre System, and the tyres supplied are Mavic’s own Yksion Pro Griplink at the front, and Yksion PowerLink at the rear. The two tyres are front and rear specific, with the Griplink designed to improve front wheel cornering grip by uses a sticky compound and ‘water evacuation tread pattern, while the Powerlink focuses on lowering rolling resistance. The tyres weigh a claimed 210g a piece.

Updated aero rim profile

Mavic’s wind tunnel has also been put to good use, with extensive testing resulting in a new aero profile being introduced for both wheelsets.  Mavic arrived at the NACA (National Advisory Committee for Aeronautics) airfoil profile after a lot of trial and error with different NACA profiles to find what produced the best results in the wind tunnel. Mavic claim the final shape offers improved stability and aerodynamic efficiency at the wind angles cyclists spend most of their time fighting.

“Across these average wind directions, we find our new wheels save watts in relation to our rivals. The new Cosmic Pro Carbon SL, for example, beats Zipp’s Z303 Firecrest 46mm rim by 2.3 watts over these yaw angles, at a range 10 degrees left-to-right,” says Brunand.

Laser treatment to improve braking

Additionally, Mavic have taken the opportunity with this second generation of carbon rim technology to use a patented laser treatment technique to improve braking performance and consistency in wet conditions, while remaining competitive with rivals in the dry.

“With the curing process we’ve developed, there is no machining, which cuts and damages the fibres,” adds Brunand. “The result is a rim surface that has almost zero variations, meaning reduced heatspots under braking and more reliable performance.

“In order to maintain this, we’ve also patented our own laser treatment – called iTGMax – for the brake track, which keeps braking consistent and free of shuddering, and maintains the carbon. For performance, it’s competitive versus our rivals in the dry, and sets new benchmarks in the wet.”

Mavic claim in the wet, the iTgMax technology reduces stopping distances by up to a third against key rivals, such as Zipp’s Firestrike and Firecrest rims – with lab tests having been carried out at Mavic’s design centre in Annecy, alongside field tests on the famous descent of Mont Ventoux.

The Ksyrium Pro Carbon SL wheelset has a claimed weight of 1,390g

Hubs and spokes

The wheelsets all take advantage of Mavic’s alloy Instant Drive 360 hub design – a dual ratchet system introduced last year at the launch of the Pro Allroad range, engaging at just nine degrees with the scope to be compatible with any type of retention system.

The straight-pull, double-butted bladed spokes remain constructed of stainless steel for both the Cosmic and Ksyrium ranges – with the Cosmics benefitting further from Mavic’s wind tunnel work with a new tapered aero design. Each are laid out in a radial 18-spoke front and Isopulse 24-spoke rear pattern for optimum power transfer. That Isopulse pattern sees the spokes laced radially on the driveside and two-cross on the non-driveside to maximise driveside dish, thus providing a better spoke tension balance between left and right flanges.

There are also disc-specific versions of both wheelsets

Availability and pricing

Availability in the UK varies with each model: the new Cosmic Pro Carbon SL C goes on sale on March 15 (£1,450 RRP), while there will also be disc sibling available a month later (£1,500 RRP). A tubular version of the disc model is already available for £1,650 RRP, while the rim brake tubular version will be on sale from July 1 (£1,575 RRP).

The new Ksyrium Pro Carbon SL carbon clincher wheelset will be available from June 1 (£1,500 RRP for rim brake, £1,575 RRP for disc-specific), while rim and disc brake tubular versions are already on the market at the same price points as their Cosmic tubular siblings.

Try before you buy

Finally, Mavic are to launch a new try-before-you-buy testing program for their range of wheelsets, called Riding is Believing.

The program offers the chance for riders to test potential wheelset purchases from selected local dealers before they buy them, free of charge.

“We’ll be working with around 1,500 selected dealers at launch, with the potential for more,” says Brunand. “All riders have to do is register for the wheels online and pick them up at their chosen dealer to ride them. Then they have the opportunity to give us feedback on whether they met their expectations, and buy them if they did.”

The Riding is Believing program is due to launch on April 15 in the UK.

Website: Mavic


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