That's the correct way assuming your rear derailleur has sufficient "wrap" capacity to handle the total teeth involved. I tend to exceed the rear derailleur's rating on my bikes by changing the standard 30T granny chainring on my road triples for a 26T. Even with a GS road rear derailleur, it's a couple of teeth over Shimano's rating. That said, the slack in small-small is minimal and certainly not enough to cause damage from sag.