I've got two sets of wheels. Alloy and carbon. For the most part I just leave the carbon wheel on (racing wheels, training wheels, whatever) unless I know I am going to be doing a lot of climbing. The alloys have the 11-28 on them and I am too lazy to swap the cassettes when I know I can swap the wheels and brake pads quicker. The alloys are 23mm wide and the carbons are 25mm wide and both run 25s which is a nice treat for me (~190-195 lbs).