ira.goldsc1527338wrote a review of Castelli Nanoflex 2 Bib Shorts on October 11, 2016
Familiarity: I've used it several times
Fit: True to size
I road these in several recent 70-90mi. days with 40-50deg. temps and some rain.
They are nearly perfect except for one issue: the seam across the back/bottom of the shorts crosses right where my sit bones contact the saddle. During some of the riding I didn't notice it while at other times I kept thinking that it could be causing some irritation. However at the end of each day's ride I did not have any added saddle soreness. Hopefully the thickness & softness of the Nanoflex material along with the thickly-padded chamois will make this seam a non-issue over the long run. However, it's location did unfortunately put a bug in my head about the possible source of some added butt discomfort...and we all know that this is an unwanted distraction when you're suffering. Castelli may have a reason for putting the seam there (perhaps to "shield" it from rear wheel water spray?); however, I'd happily trade this little bit of ultimate water resistance for not having a seam located in perhaps the worst possible location.
Now for what's great about these shorts:
1) Fit - They fit great like all other Castelli shorts I've owned or tried on which means they're sized for a lean, biker's body. So for me the fit is "true to size" while most other brands run large. The thicker yet-still-very-stretchy material makes them harder to put on vs. a summer-weight short, but while riding they feel like a "normal" race-cut bib to me (i.e., compressive/conforming but not overly tight or restricting).
2) Length - These are longer than your typical summer-weight short, which for me meant they come down to the top of my knee caps. I found this length to be great since I will generally be wearing knee warmers under them (i.e., the added length keeps the knee warmers in place better and allows the knee warmers to be pulled further down if needed).
3) The upgraded Kiss Air chamois seems to work nearly as well as the Progetto X2 (which is one of my 2-3 favorite chamois's). The cushion at my sit bones feels a bit less isolating due to the lack of the Progetto X2's gel inserts. However, I'd still consider it to be as good as or even superior to many other brand's top-end chamois's, which makes it a steal at this price point (so much so that my next summer-weight bib purchase will probably be a lower-end Castelli with the Kiss Air chamois).
4) Warmth - Definitely provides the added warmth in 40-50deg. weather that I was seeking vs. my summer-weight bibs (and I generally don't ride in temps lower than that).
5) Water-Resistance - Definitely fends off light rain and road spray. However I chose to wear rain pants over them during periods of heavy rain (for me the possibility of riding with a wet chamois isn't worth it just for the sake of seeing how water resistant this shorts are).
6) Miscellaneous - The Giro3 leg grippers have worked great for me in the past and so far these do too given that they're tighter than on a summer-weight short (i.e., since they are gripping the narrowest part of my thigh just above the knee). Finally I might complain about the bunchy traditional seamed-mesh bib straps but at this price it's hard to expect much more (and I'll generally be wearing them over an undershirt such that this issue is not really noticeable).
In conclusion, other than than the oddly placed rear seam, these shorts do what they claim to do (and do it better than the thermal shorts from Bontrager or P.I.). They are a steal at this price for something with the Castelli name on it. Buy 'em unless you see value in the extra cash needed for the likes of the Assos or Rapha thermal bib shorts.