Four-cross (4X), also called mountain-cross, not to be confused with fourcross, is a relatively new style of mountain bike racing where four bikers race downhill on a prepared, BMX like, track, simply trying to get down first. These bikes are generally either full suspension with 3 to 4 inches of travel, or hardtails, and typically have relatively strong frames. They run a chainguide on front and gears on the back. They have slack head angles, short chainstays and low bottom brackets for good cornering and acceleration. In recent years the tracks raced on have been rougher and less like those used in BMX.