EDIT: Just found something new: Mount bike and then skeleton griffon and DISMOUNT bike right after mounting on griffon, it will dismount both of the mounts and you can fly without mount.
http://img183.imageshack.us/my.php?i...8154924cm0.jpg
You will need you need to be a Death Knight and have Winged Steed of the Ebon Blade (Flying skeleton griffon), which can be purchased for ~1000g from The Ebon Hold.
And Mechano-hog (engineering motorcycle mount)
All you have to do is just mount your bike and then mount skeleton griffon.
Tried this with normal Wind Rider mounts too, but only seems to work with Winged Steed of the Ebon Blade.
Pretty useless but fun and wanted to share it with you.
Picture: ImageShack - Image Hosting :: mmownedgc7.jpg
Feel free to comment and ask about anything, Ill answer as soon as possible.
Also I havent tested this with Alliance version of the bike, so If there is an alliance player with both of these mounts, please share it with us.