“ONLY USE REAR HITCH RECEIVER TYPE RACKS”
“DO NOT USE CLAMP ON VEHICLE RACKS”
Any type rear receiver rack works. If the bikes have a slanted center tube, it is recommended to use an Adapter, that clamps under the handlebars and to under the seat,to straighten the bikes, if you are using a rack that holds the bikes by there center tube. Tray racks and racks that hold the wheels all work.