An ill fitting bike is a bad thing. When your ride mileage routinely measures in the triple digits, however, an ill fitting shoe may be worse. Too tight and circulation is cut off too loose and slippage causes painful blisters. Skiers and snowboarders have known for years: for a perfect fit almost nothing beats the Boa system. The Fizik R5 Donna Boa Women's Shoe takes advantage of the incredible precision of the Boa system while maintaining extraordinary ventilation, tough durability, and impressive light weight. The R5's closure system starts with a conventional hook and loop strap close to the toe for near infinite forefoot width control. Moving up the front of the foot, the Boa Cable dial in closure system snakes its way through four separate anchor points for complete control all the way up to the tongue. For extreme control over volume, or simply to efficiently clean the inside of the shoe, Fizik designed the tongue pad to be fully removable. To further control slippage, Fizik has shaped the heel cup at the aft position of the shoe. This feature keeps the foot in the perfect position on hard up strokes and while climbing out of the saddle. As a result, you're powering the pedals comfortably and efficiently. This has been further heightened by a variable stiffness sole construction. Underfoot, the R5 makes use of a carbon reinforced nylon outsole. And while this keeps costs down, it doesn't inhibit either comfort or power transfer. In fact, the R5 retains a low stack height and a high level of rigidity. Fizik has also engineered in trace flexibility, so the outsole drives power directly to the pedals while allowing enough movement to guarantee comfort after 80 kilometers. And on the topic of comfort, Fizik went above and beyond to make the R5 extremely breathable. The R5 features Fizik's Microtex for the support structure of the uppers and nylon mesh for the ventilation windows. Together, these materials keep your feet breathing and comfortable on long su...