Zipp’s Sub-9 tubular disc is your ticket to maximum free speed and setting new personal records. Zipp's engineers went above and beyond and actually created a disc that's capable of producing forward lift at certain wind angles for even more of an aero advantage. And it boasts Zipp's infamous toroidal bulge that smooths airflow at both the leading and trailing edge of the wheel. What's more, the bulged outer rim provides excellent control for cornering, fierce stiffness for power transfer and even nice comfort for those Ironman distance races or those technical time-trial courses. You also get Zipp’s dimpled surfaces for more aerodynamic bliss, and an incredible weight of just 998 grams so the Sub-9 is an excellent choice for even hilly courses.