Tricking is a sport with roots in martial arts and elements of tumbling and breakdancing mixed in. The quadruple cork is tricking's ultimate feat: an off-axis backflip combined with four rotations in the air on a separate axis. WIRED's Robbie Gonzalez spoke with some of the best trickers in the world to find out how they do it, what makes it so hard, and whether anyone will ever manage to pull off a quint.