The ZD1 is engineered using the highest quality carbon, Toray T700, for a lightweight, yet stiff, and surprisingly responsive feeling. The uniquely shaped tubing reduces drag, resulting in an aerodynamic, efficient flight. The frame allows for a tire clearance of up to 32mm, which is the most for any aero road / triathlon bike on the market. When compared with 23 or 25c, wider tires will not only improve ride quality, offer better handling, and increase comfort to reduce fatigue (which are three great standalone reasons to go wider), but also, the larger diameter increases the rolling circumference. Think about that. Roll faster and further. On every. Pedal. Stroke.