I wear a sports bra and often a baselayer (or two if it's cold) under the bibs. Only the jersey/jacket/vest goes on top of bib straps for the pee break reason. I'm with Bluetree. I need fewer breaks with bibs because there's no pressure from the waistband. Except in winter where I don't sweat as much. Which sucks. Which is also why all baselayers, no matter how warm, go under the bibs.