Seems then like they are being a bit ridiculous IMO. Unless they have a valid basis for the fear of you driving a motorcycle (for example if you've threatened to use it as a means to your end) I don't see why you shouldn't be able to ride your bike. We all need release from the stress(es) of our mundane and sometimes terrible lives. If this is your release, then just do it. Screw em. They'll get over it. Somethings you just need to do for yourself.