Fizik X4 Powerstrap Gravel Shoes Designed for off-road gravel bike adventures, the Fizik's X4 Powerstrap Gravel Shoes are a comfortable, reliable option for those who enjoy travelling off the beaten path and exploring the countryside. The Powerstrap Velcro closure system provides a reliable fastening system, the straps are supportive, spreading the pressure across a wide area so that there are no pressure points, and the X4 nylon outsole has a stiffness index rating of six for a great blend of efficiency and compliance. The upper features less mesh than many cycling shoes for better weather protection and they are compatible with most two-bolt, MTB style pedal/cleat systems.