Jonny Heinkenwrote a review of Castelli Nano Flex Pro Bib Tights on December 10, 2016
Castelli is based in the foothills of the Italian Alps. They understand Winter cycling.
The brilliance of these bibtights is the silver waterproof fabric used at the front of the shin. This design stops the constant front tire wheel spray from soaking through your tights at the shin. Which in turn, in conventional tights, seeps down to your socks, then to your feet. Cold wet feet are awful.
These tights prevent all this. Remember, if you are riding in actual rain to wear these tights OVER your waterproof booties (so rain cannot get to your socks).
I highly recommend the following booties for riding in wet weather: Pearl Izumi WxB, or Castelli Poggio or Castelli Tempesta.
***Sizing:. With Castelli kit, usually size up +1 from your normal street size. Italian sizing is different. Here, size up +2. Trust me, I'm not kidding. They will still be snug in the thigh.
Best recommendation: Buy two sizes. +1 and +2. Keep the ones that fit best. Return the other (with tags on, etc, of course).