Mercury Wheels

M38 Clincher Wheelset

At first blush, you might be inclined to compare Mercury's M38 Carbon Clincher Wheelset to other manufacturers' pure climbing wheels. And you'd be right to do so, at least when it comes to climbing. But these aren't just a one-trick pony. The M38s' aerodynamic pedigree, low weight, and brute strength also recommend them for all the ups, downs, and flat-outs of competitive cycling. They cover the demands of every terrain on every day of your cycling life.

The M38s' construction is informed by the Dual Carbon Layer Process, or DLP. Mercury blends high- and mid-moduli carbon fibers to straddle the best balance between the lightweight and stiffness of the former and the fatigue-resistance and durability of the latter. DLP also involves the incorporation of basalt fibers in the brake track to reduce heat build-up and increase stopping power. While reduced heat is mostly applicable to tubular wheels, the increased stopping power goes a long way toward addressing the poor braking that is one of the most common critiques of carbon wheels.

The rims measure 38 millimeters, a depth that strikes an all-purpose middle ground between straight-on aerodynamics, hiding from crosswinds, and considerations of weight for climbing. The minimal 22 millimeter width also contributes to keeping the weight down, so your rims aren't fighting you with extra material during each acceleration or on climbs, when watts are at a real premium. The aerodynamic benefits of the deep rims are further complemented by Mercury's Seamless Transition Technology (STT), which integrates the brake strip with the rest of the rim in order to eliminate any obstructions to wind flow and reduce drag-causing turbulence.

The M38s are laced with Sapim's Race spokes, their most popular double-butted model, which are capable of withstanding a claimed one million load reversals of fatigue testing while still saving weight courtesy of their butting. They connect to proprietary Mercury hubs, which engage with three pawls for a nearly immediate responsiveness that takes advantage of the rims' low rotational inertia. The front hub has an extra-wide 72 millimeter flange for reduced flex under hard efforts and confident stability at speed. Both hubs have a 15 millimeter axle that tapers to accommodate a traditional quick release and two and four over-sized bearings in the front and back, respectively.

The Mercury M38 Clincher Wheelset comes with a Shimano/SRAM 11-speed compatible freehub body and includes skewers, valve extenders, brake pads, and rim strips. Mercury recommends a rider weight limit of 250 pounds.