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Mavic Cosmic and Ksyrium Pro Carbon SL wheels review: first ride

Mavic carbon wheels
15 Mar 2016

We test Mavic’s new all-carbon clinchers to see if the updates have made a difference.

If you read Cyclist’s recent article on Mavic’s launch of its new Pro Carbon SL Cosmic and Ksyrium wheelsets (read here: Mavic launches Pro Carbon wheels), you’ll know the research and development Mavic claims is undeniably exhaustive. Mavic’s insistence on performance and reliability has meant that these wheels have taken an age to be realised, while the competition has marched ahead. But are they worth the wait?

Full disclaimer: I rode less than 50km on the Cosmics over rolling terrain, but it was enough to get to grips with their aerodynamic pretensions, and the Cosmics hold speed well for a rim that is only 40mm deep. Maxime Brunand, concept and product manager for Mavic, explained that this is down to the wheels’ NACA (airfoil-shaped) profile that is mated to special elliptical spokes.

Climbing Mavic

‘The two components work as a system to enhance aerodynamics,’ says Brunand. ‘This results in a wheel with the handling of a mid-depth rim but the aerodynamic performance of a deeper rim.’

This technology makes the Cosmics a versatile wheelset – aero enough for gains on the flat but without too much of a weight penalty when climbing. 

Ksyrium Pro Carbon SL C

Most of the time I had available to test was spent on the shallow-section Ksyrium wheelset, largely due to the mountainous topography in which we rode. As you would expect from a 1390g wheelset, they were responsive and I was thankful of them on the numerous prolonged ascents - fairly predictable wheel characteristics for a company with Mavic’s reputation for quality. I was more interested in the unknown quantity: Mavic’s new rim surface. A great deal of fuss had been made of its proprietary laser treatment, so the proof was in the braking.

Col de la Madone

Descents on the wheels were a joy. Not only was braking consistent, but there was also a level of power that I have only experienced before with aluminium rims. I could modulate my deceleration without any fear of the rims grabbing, allowing me brake much later into corners than usual on carbon wheels. The pads looked well worn by the end of the day, but what price is fun (and safety)? It is worth noting the wheels were only tested on dry roads but Mavic tests wet-weather braking extensively both in the lab and the real-world and claims similar braking performance.

Lighter weight, better aerodynamics and superb braking? It may have taken a while, but Mavic has raised the bar. Keep an eye out to see how the wheels fare in a long-term test coming soon in Cyclist magazine.

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