We love the steady sound of dual discs rolling on the track. Apparently, Zipp loves it even more than us. After all, Zipp's first products were disc wheels. And when you look at the technology and palmares of the Zipp 900 Track Tubular Wheel, it's easy to see that Zipp still holds its passion for the speed of discs. For sheer rigidity, the 900 features a pure carbon fiber construction with a 21mm maximum width. Couple that with the added strength at the rim's edge from Zipp's Kevlar stitched, Carbon Bridge technology, and you have a rim that's 50% stronger and ridiculously stiff in the lateral direction. And don't fear, these attributes didn't come at the pain of added weight. In fact, the rear 900 weighs in at roughly 1,130 grams, not only making it one of the lightest disc wheel in the Zipp arsenal, but also one of the lightest discs that we know of. A number of Zipp technologies went into making the 900 the fastest and most powerful wheels in the Zipp arsenal. First, the Multi Material Co Molding process permanently fuses a sub 200 gram aluminum hoop to a dimpled carbon structure that acts as a leaf spring for vibration and impact. Spokes laced directly to the carbon body give you the benefit of a carbon feel and aluminum braking. Next, visco elastic material is inserted between carbon laminate in the rim to reduce vibration by ten percent. Lastly, the dimples of the Aerodynamic Boundary Layer Control ABLC on the curved rim section work to create a slight turbulence directly above the rim surface. This creates an artificial boundary layer that forces the laminar boundary layer towards the forward part of the rim to become turbulent. This process enables airflow to remain attached over more of the rim for a longer period of time, providing a lower level of integrated drag. The drag that ABLC creates is called skin friction drag although it's greatly increased, pressure drag which is ten times higher than skin friction is decreased to make the 900 wheels ...