bicicletawrote a review of Castelli Ergo Tre Bib Short - Men's on May 19, 2011
I am 5'10" ~170, about a 40" chest, 32" waist and went with an XL and it fits good. I normally wear a Medium in most other 'normal' bib sizes. Took it out for a 35 mile spin and had no issues at all. Very comfortable & breathable.
If I had to mention one downside, I'd say the north/south fit felt a little tighter than I'd prefer when standing (not sitting/riding). The width of the legs, waist and chest were fine, but the length from shoulder to crotch feels as if it were for someone a little shorter than me. Rides up a little, not too bad though.
Go up 2 sizes and you should be good to go!