Modern trail bikes maintain composure in situations once reserved for downhill race bikes, and as a result, wheels are now confronted with more abuse than ever. At the same time, riders are demanding bikes that are light enough to comfortably pedal all day. These seemingly incompatible goals are exaggerated on 29 inch wheels. Solving this problem served as the motivation for SRAM to build the ROAM 60 29in Carbon Clincher UST Wheel. SRAM's engineering team must have been tempted to go all out with the weight reduction of the ROAM 60's carbon rim. Thankfully, though, instead of focusing on shedding grams at all costs, SRAM placed a higher priority on durability. This resulted in the ROAM 60 weighing in within 10 grams of its aluminum counterpart. And this starts to shed light onto why the carbon fiber ROAM 60 is both stronger and stiffer than the aluminum ROAM 50. A quick glance at the cross section of the rim reveals a main cavity that's thinner on the sidewall than at the bead hook or the spoke bed. The sidewall thins gradually, which provides a strong base for the bead hook. As a result, it resists deforming under hard impacts. SRAM calls this rim profile Taper Core, and it essentially means that SRAM has optimized the carbon layup in order to place more material where it serves durability, not where it doesn't. Ultimately, this results in a thinning of the rim profile elsewhere in order to optimize the balance between weight and strength. The Taper Core rim profile is shared with the alloy ROAM rim, but unlike its alloy counterpart, the carbon ROAM 60 rim gets a boost from SRAM's Carbon Tuned construction. Basically, SRAM combines woven carbon fiber with unidirectional carbon, and the result is a wheel with a precisely tuned blend of stiffness and compliance. The internal construction of the rim employs woven directional fibers, which enables the rim to compress vertically under high loads. This yields an added degree of compliance in comparison to an alumin...