3x2x1 is the standard that is posted all over the net but I find that if I foil them for 2 hours I end up with mushy, overcooked ribs. I do agree, depending on temps inside the cooker, that 1 hour on the front end can be bumped up a bit. If I am not getting them hot enough I go longest on the front end with a 2x1x1 or so. This is all just a starting point to get you in the game. You will have to play with it on your own cooker to get the ribs you want. Also, I only cook spares - Baby backs are resturaunt gimicks that are smaller, less meaty and more expensive per pound. If you are going to cook ribs - cook ribs and not some cut down version of the real thing. JMO
Bob Urban