Depends. If it is just a plain ol' round bell boot, then it doesn't matter as it will slightly turn when worn. If it has little bulb type things on the inside, then that has to go at the back, and the velcros will more then likely end up at the outside or front.
Thanks. They're not MY bell boots, they're my neighbor's. Maybe I can get a pic of them. She says the velcro faces front, I say back. (cuz you want the edge of it to nearly touch the ground on the back, right?)
Yes, you want it to just touch the ground, and it would happen at any point of the boot, not just the velcro part. But you also have to consider what bell boots designed for, and that is for over reaching. If you put the velcro at the back, and the horse over reaches...then it could possibly tear the velcro open and leave the horse bell bootless. Makes having boots on pointless.
The front or the side would be a much better way to go, as they shouldn't turn so much to get around to the rear of the hoof.