I'm 5'10" w/ a 31.5" inseam and was riding a frame w/ a 56cm effective top tube. I recently got sized up to order a new bike and was sized up to a 54cm frame. The effective top tube on my new bike is 54.8cm.

Looking back at my old bike, I was too stretched out and wasn't too comfortable riding on the hoods or drops. On the 54cm, I comfortable in all the bar positions.

just my two cents