swlwrote a review of Castelli Nanoflex Bib Shorts on January 12, 2013
Referring to Brian's post, I am about 140 lbs with a 34" inseam and these bibs fit great. The longer inseam gives me coverage that I usually can't find.
A medium fits me fine. The chamois works well and has plenty of thickness but does not bunch up.
I hate that they are more suitable for cold weather or I would buy several for year round.