There's a lot going on behind the scenes of the Zipp 404 Firecrest Carbon Tubular Road Wheel, but you don't need to understand all the physics to know that this thing is speedier than Gonzalez. Plenty of wheels are made of carbon fiber, but the 404's unidirectional weave and silica ceramic fabric give it an absurd stiffness to weight ratio, while the dimpled surface structure actually reduces drag, a lot like the dimples on a golf ball. Zipp also employed a technique called Aerodynamic Boundary Layer Control, which basically increases air friction resistance while dramatically reducing air pressure resistance this might sound bad, but pressure slows you down 10 times more than friction, so the increased friction of ABLC actually helps you speed up. It also helps the 404 maintain its wind slicing properties even when you're riding in real world sidewinds and not carefully controlled wind tunnel headwinds. Carbon's notoriously stiff, which is great for hard pedaling not so great at smoothing out road vibrations. To get around this, Zipp fused an aluminum hoop to the carbon, which acts as a gentle spring to reduce vibration, and also provides a better braking surface, so you can avoid the occasional sketchy stopping power of carbon rims. There's also a super secret visco elastic material between layers of laminate, which Zipp claims reduces vibration by 10%, giving you a smooth, more comfortable ride. The new 188V9 rear hub and Sapim X Ray stainless steel spokes boost stiffness even further, while the Zipp 88 front hub keeps you rolling smoothly and the ability to run SRAM, Shimano, and Campagnolo cassettes means you won't have to retrofit your whole bike just to accommodate your new wheels.