I wear an 8-1/8 hat . Not easy to find headwear in that size so I wear a do rag a lot plain cotton. You can wet it and use evaporation to cool or dry it soaks up sweat. Years ago I took an old worn out Doo rag apart made myself a pattern and make them myself. Just grab a quarter yard of fabric from the novelty isle. I can make one in 10 minutes always have an extra in my trunk bag

For sun protection I use the black version of this:

https://www.rei.com/product/129013/p...lite-skull-cap

I use these; got mine in a cheaper off-brand but they're the same stuff: polyknit tube.

You can also get lycra balaclavas from Aliexpress, which are exactly that, quik-dri material balaclavas. I often use a mask shaper (a plastic cage thing from the pandemic that stopped masks wetly slapping your nose and mouth) under them for winter riding, and for longer days in the summer to keep the sun off. It's socially acceptable to wear a scarf/balaclava mask like that while cycling in Korea, though, and I have seen some weird freakouts online about them, from Europeans in particular who would seemingly rather be sunburnt than hide their face like that. I guess it's some honesty thing with northern Europeans? They get really weird about covered face cycling when they're tourists here as well, in my experience, bemoaning it as a pernicious fashion, rather than trying to understand that it's for sun/bug/wind chapping protection.

I'm a big fan of the Pearl Izumi Transfer Lite Skull Cap. SPF 50, sells for $25. They also add that they are constructed of "Ice-fil® cooling fabric technology" whatever that is.

Try Headsweats

These work great for me. They prevent sunburn in places where my hair is thinning (I've got a thin spot, not really a bald spot....yet) and they are excellent at cooling in the heat. I don't know what they mean by "cooling technology" per se, but they get soaked with sweat and then the evaporation is nice and cooling. Otherwise, much of the sweat just drips off (into my eyes!) and the cooling isn't as efficient.

Great, now he knows there is such a thing. Can’t imagine the photos from that thread.

.

from a bald guy, another vote for Headsweats

just wear a wig

I just got a Castelli Summer Skullcap. I've worn it just a bit so far, and I like it. Until now, I've been wearing cycling caps.

Everyone's different, but I think I might find I prefer not to have cotton because it holds the sweat there. Wool and synthetic let it wick away. I've been wearing a lightweight wool cycling cap (from Walz), expecting it to make me hot, and it doesn't.