I have these also. Note that they have Italian sizing, which means that they are very small. Even though I wear a large in Performance Ultra bibs, and Extra Large in Voler bibs, I got XXL in Castelli, and they are still pretty snug, particularly in the length of the straps; I could use another inch or two, Its OK, though, my wife and I have already had as many children as we want ;-)

For reference, I am 6-0 tall, 210 pounds, and have a 38" waist.