Mavic

Ksyrium Pro Exalith SL Wheelset - Clincher

Just about everyone in our circle of pedal turners has ridden Mavic's Ksyrium wheels before, but few have ridden them like this. The Ksyrium Pro Exalith SL Clincher Wheelset represents the top of the French brand's do-it-all wheel family, elevating the Ksyrium almost to the R-Sys SLR's level. In fact, except for the branding and bearings, which are slightly heavier in the Ksyrium, the two wheels are the same. This includes sharing the Tracomp carbon fiber spoke technology, and the two are the only wheelsets in the world that can make that claim. If the Pro Exalith SL is the king of the Ksyrium line — and it most certainly is — then the path to the throne was paved with carbon fiber Tracomp spokes.

The Tracomp spokes feature on the front wheel and the rear non-drive side, stiffening the wheelset by reducing spoke stretch and compression. This drastically reduces rim deflection during the lateral load of hard efforts and fast cornering, so the rims respond more like super-stiff carbon. But the rims aren't carbon, they're alloy, so Mavic can treat them with the Exalith II process and increase stopping power in dry and wet conditions by a claimed 18%. A new pad/brake track interface reduces engagement noise compared to the previous generation of Exalith, but we actually like Exalith's jet-engine hum — especially compared to squealing, unresponsive carbon brake tracks.

Thought the wheels substitute Tracomp spokes for the Ksyrium line's usual Isopulse design, it still adopts many other qualities that have made the wheels Mavic's go-to. The hubs house Mavic's QRM+ bearings and FTS-L freehub in a carbon body (front — a departure from most other Ksyriums) and an aluminum body (rear), and the bearings are adjustable with an Allen key and Mavic's included wrench.

The Pro Exalith SL maintains the Ksyrium line's traditional internal rim width of 15mm. Along with Mavic's latest generation of milling, Inner Spoke Milling 4 Dimensions, the narrow footprint gives the wheels a claimed weight of just 1,355g, with most of the savings manifesting in the rims, which is where low weight is most important. Lower rotational mass at the circumference means less inertial resistance, so the wheels spin-up faster out of corners and while punching it on climbs.

Obviously, the Ksyrium Pro Exalith SL isn't on trend with the 22, 23, or even 25mm external rim widths manufacturers have begun rolling out. Like many cyclists who pore over spec sheets, we initially saw the narrow width as a refusal to adapt to new technology; however, it turns out that the International Organization for Standard (ISO) actually only recommends those expanded widths for use with tires much larger than what we typically ride and race on. For 25mm tires — arguably the new standard — ISO recommends a maximum internal rim width of just 17mm for rims with bead hooks.

While developing a system to meet ISO recommendations, Mavic also found that the 15mm Ksyrium Pro Exalith SL rims still benefit from the increased air volume of 25mm tires, stay well within the ISO's dimension limits, and manage to eke out some weight savings compared to rims 17mm and up. The reason to stay relatively narrow, we now understand, is one of sound engineering triumphing over adherence to industry trends.

The tires themselves are also exemplary specimens of French engineering. Designed by Mavic and built by Hutchinson, the Yksion Pro tires employ different compounds and constructions for the front and rear. The Yksion Pro Griplink on the front wheel features a soft, sticky compound, a tread pattern designed to cut through water, and KEVLAR reinforcement for grippy road feel with extra flat protection. For the rear tire, the Yksion Pro Powerlink features a nylon reinforced casing and a slightly harder compound than the Pro Griplink. The rear tire's tread pattern is designed to increase rolling efficiency while still maintaining a supple road feel.