We have designed our FAT RACK to suit Fat bikes with tire widths ranging from 4 up to 5. 25. The FAT RACK comes in CKD Flat-pack form only, so it can be adjustable and simply screw together in 3 different widths, 4. 25, 4. 75 and 5. 25. Simply assemble the FAT RACK to the width that closely suits your Fat bike tire size. Screw the base bent tubes to the inside holes for the narrow 4. 25 width, the outside holes for the widest 5. 25width and one outside-one inside hole for the 4. 75 width. Wheel your Fat bike into the FAT RACK with either the front or rear wheel, very quick and easy.