Wheels

Mavic Ksyrium Pro Carbon SL C carbon clincher wheelset – review

Superb all-round performance for riders in the market for a stiff, lightweight carbon clincher with first-class braking

The Mavic Ksyrium Pro Carbon SL C carbon clinchers deliver very impressive all-round performance. They’re light enough to give almost any bike a new lease of life, helped by the stiff construction, and deliver outstanding braking performance for a set of carbon wheels.

Back in March, we headed out to Annecy and Nice for the launch of Mavic’s latest carbon clincher wheelsets: both the Ksyrium Pro Carbon SL C hoops we have here and the deeper Cosmic Pro Carbon SL C wheels.

The two wheelsets share a similar design, with the key difference the rim height. The Ksyriums have a rim depth of 25mm and come with a claimed weight of 1,390g, while the Cosmics are deeper, with a 40mm rim and claimed weight of 1,450g. Do you place more importance on super-low weight or improved aerodynamics? Take your pick – both wheelsets come in at £1,600 with tyres included.

Mavic’s first carbon clinchers

You can read our full report from the launch here but to recap: the latest Cosmic and Ksyriums are Mavic’s first full-carbon clinchers, with the French firm first having first flirted with a carbon-alloy clincher design in order to bring a ‘carbon’ wheel to market.

While Mavic’s initial design sought to combat long-standing concerns about the ability of carbon clinchers to dissipate heat, these second-generation wheels have been developed using a new manufacturing technique. The carbon layers are moulded into a single, seamless piece, said to increase both the structural integrity of the rim and the melting point of the resin used to glue the carbon fibre layers together, and subsequently protecting the rim from the high temperatures caused by heavy braking.

What else is new? The rim has also undergone a laser treatment, said to improve wet weather braking, while the 17mm internal rim width is optimised for use with 25mm tyres.

Of course, manufacturers always like to highlight their latest and greatest innovations and products in sunlit surroundings – just enough to give an impression of their capabilities – and the early-season Paris-Nice sportive we rode on both the Ksyriums and Cosmics was no different. As a result, I’ve been keen to get my hands on a set to test in what us Brits will call ‘the real world’, to see if they pass muster on our less-than-perfect roads and in a variety of conditions.

My main test arena is around Bath, complete with regular trips to the Mendip hills, while testing for the Ksyriums included the first two marathon stages of the Deloitte Ride Across Britain: Land’s End–Okehampton, featuring regular steep and punchy climbs for the 103-mile duration, and Okehampton to Bath, with a little less punchiness over a similar distance, but more in the way of variety with significant climbs and flat riding in the form of Cothelstone, Cheddar Gorge and the Somerset Levels.

First off, a concession. All of Mavic’s hoops are sold as a wheel-tyre system and I’ve rated the supplied Yksion SSC tyres from previous experience, but owing to damage to the front GripLink rubber in transit, I swapped in a set of Continental GP4000 II tyres – an upgrade of the kind many potential buyers might be tempted to make thanks to their well-reputed all-round performance. Therefore, we’ll focus this review on the wheelset itself.

The Ksyrium Pro Carbon SL C has a rim depth of 25mm, whereas the Cosmic Pro Carbon CL C measures 40mm

Out on the road

With that out of the way, the Conti’s fitted and supplied Yellow King carbon brake pads installed on my Canyon Ultimate CF SL 9.0 test rig, I had an opportunity for a couple of recce rides to familiarise myself with the hoops that I had such fond memories of from my time in Nice. In short, the sensations were very much the same.

What stands out first is the responsiveness you feel when you put the hammer down. Whether out of the saddle, or you’re content to stay seated and build speed gradually, the low weight and stiffness afforded by carbon construction means you’re never wanting for additional thrust. Teamed with my test rig – a machine that naturally laps up climbs – and the Ksyriums are a joy to use in anger, with efforts laid down with precision and poise.

With a rim depth of 25mm, aerodynamics don’t really come into the equation here – particularly when you also have the 40mm Ksyriums in the range. Still, Mavic have developed a new rim shape for both wheelsets, with a rounded profile based on a NACA (National Advisory Committee for Aeronautics) design, and out on the road, the wheels behaved beautifully in all conditions throughout testing.

Testing included the first two days of the Deloitte Ride Across Britain (Pic: Threshold Sports)

Day two of the Ride Across Britain allowed me to really open the taps across the Somerset Levels in terrain not necessarily naturally suited to a relatively shallow wheelset like this – and once more they impressed. Sure, they may not offer the improved aero performance of the Cosmics, but the low inertia and rigid platform ensures the Ksyriums lapped up the punishment with aplomb.

While the 17mm internal rim width is fairly conservative by carbon clincher standards (the new DT Swiss ERC 1100 Dicut rim is 19mm, for example), it matches up well with 25mm tyres and, combined with the carbon layup, ensured the smooth performance I felt on the billiard table roads in southern France translated strongly on rough UK tarmac, too. On the quiet single-lane roads, complete with the odd pothole and a lot of creases and gravel deposits, used for a lot of the Ride Across Britain’s first stage through Cornwall, they did a superb job of consistently and predictably easing my path. No uneasy bouncing, no shimmying, and no rattling at the rim at all, contributing to the overall feeling of a very quick set of wheels.

Consistent, reliable braking performance

One of the major innovations Mavic have introduced on these wheels is the laser-etched iTgMAX treatment on the brake track. As a reminder, it refers to the seamless layup of carbon fibre used in the construction process, and the hot laser machining then applied to the track itself for greater feel, power and consistency.

I won’t beat around the bush here, this is one of the most impressive areas of the wheelset, without a shadow of a doubt. From the predictable application of stopping power, to the fade-free reliability over prolonged braking, the Ksyriums exhibit some of the best overall braking we’ve experienced from a set of carbon clinchers.

The freehub emits a reassuring purr but, combined with the hum produced by braking on the carbon rim, means these certainly aren’t silent hoops

Of course, the rims must work in tandem with a decent set of brake blocks and Mavic supply a set of Swiss Stop Yellow King pads here, contributing to the first-class performance (there’s got to be some quiet colour-matching going on there, too). As you’d expect from a soft compound, they do wear quicker than most – it’s a relatively small price to pay, given the excellent all-round braking, but an additional one to consider.

Conclusion

The Mavic Ksyrium Pro Carbon SL C wheels are fantastic, high-performing all-rounders, very adept at practically anything you throw at them. Barring when absolute aero efficiency is the primary consideration you need to make, when the equivalent level Cosmics are likely to be the adaptable wheelset you’ll be after, you can be sure the Ksyriums will reward hard riding, thanks to the low weight and impressively stiff design, paired with excellent braking to bring you to a halt again.

Pros

Lightweight and very responsive
Outstanding braking performance
Wide rim for use with 25mm tyres

Cons

£450 more expensive than the lighter, alloy Ksyrium Pro Exalith SL wheelset but fairly-priced for carbon hoops
The recommended Yellow King brake blocks can wear down quickly