If you're in the market for deep dish carbon rims, then you've probably already made the assumption that the number in the M5's name denotes a depth of 55mm. The rim's width is left out, though, and rim width is a big deal these days. The M5 is a solid 24mm wide, which means you can run lower PSI for a more comfortable ride that corners with unparalleled confidence. Wider rims also have some counter-intuitive effects when compared to those standard 19mm rims: they actually decrease rolling resistance and increase aerodynamics. The M5s' construction uses Mercury's Dual Carbon Layer Process or DLP. DLP blends high- and mid-moduli carbon fibers to tease out the best balance between the lightweight and stiffness of the former and the fatigue-resistance and durability of the latter. DLP has also recently been updated with a newly engineered brake track material, improving stopping power over the previous, basalt-infused design. This increased confidence goes a long way toward addressing the poor braking that is one of the most common critiques of carbon wheels. The aerodynamic benefits of a deep dish rim 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 result of this construction is a wheel that balances the above qualities with considerations of weight for what Mercury claims is its "most popular wheel by far." The M5s are finished off with Sapim's indefatigable CX-Ray spokes and Mercury's own hubs. The rear hub includes a generous six pawls for an engagement that's as close to immediate as anything we've seen on the market today, and the front hub has an extra-wide 72mm flange for reduced flex under hard efforts and confident stability at speed. Both hubs have a 15mm axle that reduces to accommodate a traditional quick release and two and four oversized bearings in the front and back, resp...