I'm guessing Ghost Rider is Big in Japan?
Honestly, it seems that there is no right way to approach Hell Biker. If you don't void Force or Fire, there's obvious problems. Yet it may not be possible to void one without being weak to the other at this point. If you void one but are weak to the other, he'll exploit the other, creating another problem. The biggest problem though, is just that he pretty much hits hard all around, and you may need 2 characters who have Media like I had. He simply hits too hard for players who are not overlevelled. Dekunda doesn't help either, but the good news is he doesn't use it the moment he's debuffed like Matador does.
If you can void his force attack w/o being weak to fire, or keep from being killed by his fire attack long enough to buff defense and agility, that's the way to go. However, I was not able to do that. So I did the alternative, which is to void fire with the demi-fiend(making him weak to force), and use 1 buff and 1 debuff, preferably Agility. Sure he'll keep removing them but as long as you're not putting all your magic and turns into buffing and debuffing it won't be too problematic. Plus, his force attack doesn't do a whole lot of damage, even if you're weak to it. So if he uses this attack a lot, he at least won't be doing massive damage to your party.
It also helps to have a demon who voids, absorbs, or reflects force, as you'll want to waste as many of his press turns as possible. The reason for this is that later on he gives himself more press turns, which is also why I recommend buffing and debuffing Agility, albiet sparringly for reasons stated above. Also, Dark Might or Bright Might are not required, but I strongly recommend having at least one demon that has one of the two.
It may still take a few tries, but at least this method is fairly safe.
