I'm not sure if Joes is reading this. But I hope Ludi will read it and tell him about it.
Indeed, Joes design is very interesting. I like the minimality. I think it is aluminium, but he can tell for sure. Maybe he wrote it someplace else in the forum.
Anyhow, here is a bit more about Joe: http://adinfinitum.de/Rollerskate/people/joe90/index.php