Why wouldnt you park it on the street Geeto? I am going to paint, leaf and then clear. Not going to leave it exposed. I will probably end up giving the paint to a friend who does furniture resto.
Well, if you cover the bike the constant rubbing of the cover in the wind on exposed gold leaf will wear it down pretty quick. Add that to the airborne contaminants that make breathing in NY like smoking a pack a day, the acid rain, the little ghetto kids that put their hands and other things all over your bike, The salt NYC uses on the roads in the winter, and the errant parkers who think a motorcycle is ok to bump like a car is ok to bump and you can see this is a harsher enviornment than most for this kind of paint exposure. You don't see a lot of gold leaf on signs anymore round here for a lot of the same reasons - the pollution eats it. A lot of the industry has made the big shift to vynil. NYC is a rough enviornment for a bike, espically one that is outside 24/7. I cut my chops at a sign-o-rama and even some of the vynils peel after a certain number of years in this enviornment.
Another thing to consider is gold leaf cannot be touched up easily, not as easily as paint anyway. You can't touch up vynil either but basically another $5 and you have an entirely new piece.
Personally, the stuff that holds up the best (as far as I have seen) exposed to the elements is one shot paint. You can lay that on and it will hold pretty well, still susseptible to rubbing but hey everything is.
Why don't you talk a little bit more about what design you have in mind, what your goals are, and we can help guide you in the best way in accomplishing it.