Prevent brain freeze on your next sub-freezing adventure with the Castelli WS Skully Cap.
Typical excellent Castelli quality. Used it many times from mid-20's with 20mph winds to low-50's. I would personally only use this up to mid-40's. It tends to be too warm after that, especially if the sun is up. It fit me well, but fair warning, I do have a Large head (wear Large in Bell and Giro helmet sizing). I like the look, the cut, and how the ear-flaps taper down to the tail at the back of the neck. I don't have to do the stretch/pull that I normally do with my other skull caps that do not have this long tail.
I have a fairly big head (both physically, this cap fits well, and otherwise, just ask my wife). This cap is snug on my head, and fits well under my helmet. Strangely, it reduces wind noise around my ears, making it actually easier to hear overtaking cars. The effective range for me seems to top out at about 45F. I've worn it down to about 30F, and have not wished for any more warmth.
I've had a great experience with this cap as an additional layer when it gets into the 20s. I use it with the Castelli Viva Thermo Skully Cap underneath. I agree with Darrel's review that it is a little on the loose side. That works fine for me since I use it as a second layer, but I'd be cautious on the sizing if I were looking to use this as a single layer.
This will be good for sub-45 degree rides but anything much more than that will leave you sweaty. I have a large-circumference head (59cm) and finding headgear that isn't overly tight can be a challenge sometimes. This is a good fit, extra wind protection over forehead and around the ears, the tail over the back of the neck seems a little over-engineered but it doesn't get in the way.
Have had a few brisk morning rides already with this cap. I have a big head and it fits me great. It is also pretty thin which makes it fit nicely under my helmet. Totally windproof it actually get a bit warm going uphill but I suppose that is the point.
Warm but too loose, keeps going up from ears when riding .