My TB is thin skinned and sensitive. Regular Davis bell boots rub him raw in ten minutes, splint boots cause rubs. Even my gorgeous Beval leather boots rub him. Said rubs instantly cause head bobbing lameness which disappears as soon as boots are removed He's not the most stoic guy.
Because of that I've just not ridden him in anything, but as he's gotten more fit he's knocked himself a lot. As he's gotten stronger, it's happening less. but his exuberance learning to jump has caused him to catch himself by overreaching.
Suggestions for appropriate protection? Especially bell boots that don't rub?
No, not fleece lined. Speaking from experience...they make things worse. Had a horse for awhile who had white socks and pink skin and got rubbed by every bell boot I put on him (which, of course he needed 24/7). The fleece lined ones were some of the worst because they get grit and dirt stuck in the fleece. The best were the Classic Equine 3X No turns. He did quite well in those and I've used them regularly ever since on everyone who's needed bell boots, including my current guy who is very sensitive.
Don't have too much to suggest for other boots. Make sure they fit well and are kept ridiculously clean. Maybe try some baby powder on everything before putting them on (my horse likes this for his xc boots that every now and then threaten to rub him). Obviously, make sure his legs are very, very clean, too.
While I can use most things on my horse (as long as he's clean and the boots are clean), he does go through phases where his skin is more sensitive and threatens to get rubs. If we're in that phase I use either polos or wool fleece lined boots (which aren't nearly as bad as the fleece lined bell boots). Otherwise, he does well in Woof boots...as long as they're clean (see the trend??).
I noticed that having the bell boots a little larger than normal worked for my thin-skinned OTTB. Not so big he'd trip on them of course, but looser around the top than what I would put on another horse. You could get something like the Quik-wrap bell boots from Professional's Choice and play with the looseness to see what works.
Also speaking from experience, I agree that not all fleece bells work, but the Walsh fleece lined are different, in my experience. And I made sure that they were snug fitting to prevent spinning as well. I'm not sure that there is such a thing as a horse with thinner skin and a finer coat than my horse - he is like a hairless cat and also has one white/pink leg.
OP - you may have to experiment a bit to find something that works for you. I also rotated through boots sometimes so that no one boot had a real chance to rub him. Of course, now he doesn't wear them anymore because we've finally gotten him trimmed properly and he is no longer overreaching!
You need bell boots without velcro. I have tried velcro boots both with and without fleece... both gave my horse serious rubs. I'm pretty sure it is the gap in the side of the boot that causes the rub. I use the KL Select pull ons. They are actually pretty easy to get on and do not rub at all.