Good luck on your ride! It sounds like you're recovering well. I had tendonitis in my ankle last December and it's still swollen. I really miss that bone bump on the inside of my ankle...I haven't seen it for 9 months now! I wrap it with sports tape and an ace bandage every time I ride, even if it's just a short ride. Sounds like your brace helps, so I would definitely wear it on your century. Maybe take some Aleve or ibuprofen as preventative medicine before your ride. And if you could ice it at the lunch stop, that might help too.