The sole of a cycling shoe will tell you a lot about what kind of shoe you have on your feet. SIDI’s Vent Carbon Sole is the lightest, stiffest sole with vents that can be opened and closed providing you with a four-season cycling shoe. Shoes with the Vent Carbon Sole are designed for the racer who needs to maximize on all features of his cycling gear to be comfortable as he races fast. The Wire Carbon and Five shoes feature the Vent Carbon Sole. The Twelve Carbon Composite Sole is a more traditional sole made with nylon and carbon fiber. The Nylon doesn’t absorb water and as a result it maintains its rigidity. The Ergo and T4 feature the Twelve Carbon Composite Sole. The Millenium Carbon Composite Sole has carbon fiber injected into Nylon creating a rigid base that doesn’t absorb moisture. The anti-slip toe insert and replaceable polyurethane heel pad that are designed into the Millenium 4 provide a closer fitting shoe. The Kaos, Genius, Level, and Tarus feature the Millenium Carbon Composite Sole. While the sole is the first feature mentioned, it is not the only piece that distinguishes shoes from each other. The Wire and Ergo Shoes are closed with the Tecno-3 Push System that has an unbreakable wire adjusted with a turn of a dial. This system works along the entire length of the shoe and the adjustment is fast and exact. The Ergo 4 and Kaos are tightened and loosened at the lower half of the shoe with the Tecno-3 Push System and at the top with the a Caliper Buckle. It doesn’t adjust as quickly as the shoes with just the Tecno-3 Push, but some may feel better with the buckle. The Genius and Level shoes have the Caliper Buckle along with two Velcro straps. With SIDI’s closure systems, all the shoes stay securely closed when you are riding, sprinting and climbing. The Tecno-3 Push/Caliper Buckle gives you a much more exact fit than the Velcro. For the cyclist with wider feat, the Mega shoe is an option with the Ergo and Genius road shoes.