Tumbl Trak Forster Bar Skills Trainer Tumbl Traks Forster Bar is a training aide intended to help perfect shifting for bar skills such as clear hips Developed with Coach Tom Forster, the Forster Bar is an inexpensive, useful training aide that every gym should have The octagonal ends allow gymnasts to practice skills, such as a straight-arm backward roll A rubber coating covers the bar, and gives a good grip, making the bar a safer training device