These bibs really do the trick in keeping the cold off when the temps dip below 50. I've used them predominately in 40-55 degree weather and have absolutely loved them. They fit well and the chamois is comfortable enough for long rides without really noticing them - which is great.
I bought a size small for winter riding. It felt a little tight in the beginning but after break-in or three four-hour rides and three washings the fit is perfect. The compression on the legs and the strap tension are just right . The moisture transfer or wicking feature works. After a hard long ride I dont feel wet in the chamois area. It is very comfortable. Nice seamless straps and overall clean cut. Unlike my other bib-shorts I want to change right away upon arriving home. With these bib-knickers it felt like I want to wear them all day. I also bought the Castelli Sorpasso2 bib knicker (medium). The fit of the Pear Izumi (small) is better for me. My measurements chest 34 in, waist 31.5 in, hips 33.5 in, mid-thighs 18 in. I hope this helps in deciding your size.
This must be Pearl Izumis lower-end chamois, because it is bulky and uncomfortable compared to every other pair of PI bibs I own. The bibs themselves are nicely made and do keep my knees and thighs warm on chilly or damp days.
I am a big fan of knickers. Rarely if ever do I wear a full tight, as the shins are not that sensitive to cold. And if it's that cold that I am worrying about cold shins, well, I'm headed to the gym instead of outdoors! Having said that, I am also a big fan of PI, particularly their various bottoms. These particular knicks have modest loft, a great chamois, and the best leg grippers I have experienced yet. Hopefully they will also prove durable, as have most of my other PI pieces.