Even in a world of formed and fit synthetic shoes, pre-race break-in remains essential. New is beautiful for the first three miles until the blistering truth takes hold. Once shoes lose their out-of-the-box stiffness, take them for a 10-mile spin. If the shoes fit, wear ‘em. Otherwise select another pair. Our trail-savvy testers recommend the Mammut MTR 201 Pro Low Trail Runners, winner of Active Junky’s BadAss Gear Badge for durability on the red dirt and slick rock trails of Utah.