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.