Thanks for posting this question. I also get hair wrapped around the large wheels, not just the casters. This was from back when I was in nursing homes. It seldom happens now that I'm home. I'm very careful inside the house. Of course, once outside, we have no control.
lessismore, I get thread wrapped up in mine and use a seam ripper to cut it, then you can easily unwind it.
A funny thing: I love tinsel on my Christmas tree, but somehow I get it clinging to my plastic rims covers. You have to literally pull it off because of the static electricity and it gets all over the house, then ends up wrapped around my castors. My husband asked me yesterday, "Why do you brush against the tree?" I told him that I didn't even touch it! As I left the office I went by the tree and he burst out laughing. Even though I was several inches away from the tree, the tinsel was reaching out full length to grab my wheels. I wouldn't have believed it if I hadn't seen it.
That's so funny, crepe. And it will probably be a new 'clue' in some forensic crime story...since they are ever on the lookout for weird quirks of science.
lessismore, now that you mention it, I gotta clean my casters! To answer your question though, I don't know of any solvent thatd break down the hair. I'd be worried about it damaging my casters to be honest.