You are so lucky. At 5'4" I can never find bikes in my size to test ride. Bike shops carry 54, 56 and 58 but not 49 or 50cm with any regularity. If they do, it's only the aluminum models, never the carbon ones. I've ridden a 49cm Allez for the last 18 months, which feels like it's fit decently to me. However in a year or three when I'll be looking to upgrade to a carbon bike and there won't be any way for me to test ride them. Which will likely end with me riding a Tarmac, as it's essentially the same bike as the one I'm riding now, just in carbon.