They can both easily be summed up with "Young motorcycle gang becomes pawns of Satan" in one way or another
In Psychomania some rich british snots have a bike club and they kill themselves one by one then come back from the dead because of Satan. They're club is called the Undead, very fitting.
Werewolves on Wheels. Doesn't make a lot of sense, and only has werewolves for a few minutes at the end but it's totally worth it. This ones different than Psychomania, they just want to party and then they get in on some sacrificial shit and drink some wine thats probably the blood of Satan. Its worth a look if you like cheesy old bike movies and werewolves and Satan