one i prefer.
this one is preferred by a lot of people. pick up an end of the rack with a pair of tongs, try and bend it or probably give a little bounce. if the ribs are done, you should be able to see a crack appear. the bones are not entirely done if a small crack appears on bending. a perfectly cooked rack of ribs should almost be ready to break away. doing it a couple of times will give you the what to look for. this test works well for most people as each rack might take a different time to cook. a simple thing to note here 