I bought some Castelli bib knickers last year. They have an inner fleece lining and should work for me down into the 30's. Leg warmers have the advantage of being removeable should it warm up and can include fleece lining but you may need something to wear under your normal bibs since those aren't insulated. I do have a pair of tights that I could wear over regular bibs but haven't had the occasion to use them. All cold weather clothing is subjective as people have a wide variation of cold tolerance. I've seen lots of people bundled up when temps get down into the 60's and others wearing shorts in the 40's. For me, hands and head get cold first, then arms, and legs last.