[SwedeMarine]

And yeah the stats would be better on a bike, but I imagine my warband's sorcerer lord levitating through the battlefield shooting psychic blasts of power from his mind. Putting him on a bike just makes him seem less badass and quite silly.

So Model him floating on an ethereal disc not unlike a disc of Tzeentch and use that as a counts as Bike. Im sure most opponents would not pitch a fit about this and you get to justify his bike stats while also sticking to what you want from the mini. You can model and Substitute anything you want in this game which is why it appeals so much to some of us. the disc could be made up of greenstuff and zombie/skeleton bits.