A "slightly smaller" size in an Aurora would be a 53cm...which would be rather weird for somebody your height. I'm only 5'6.25", and I'm in between a 50 and a 53cm. I'll be going with the 53cm because I prefer a slightly larger, rather than smaller bike. Btw, my PBH is 32", almost 33" with shoes. The standover on the 53cm gives me about an 1.5" clearance, which is fine for a touring bike. I do have to shorten the stem to 80mm, though. I would think that a 55 would be the smallest Aurora you should consider...unless you like riding a very small bike.