So ive been riding fixed for a year or so now and love it and im in the market to upgrade over my dawes and while looking around im seeing all these "trick" frames and majority of the ones i see the top tube slants back twords the seat post, im just curious as to why is that and what is the big advantage of having a trick frame?

Also a little random but my friend ordered the Vilano Zulu(I know...) and he wants to know if anyone has had enough experience with one to tell if it can bar spin? ha thanks guys.