We've seen rust on bikes before, there both deliberately, as on rat bikes, and not-so deliberately, as on all the bikes I've ever owned, but rarely have we seen it look as good as this. These two Wrenchmonkees Z750s feature different approaches to corrosion. The first has a naked tank, scoured with steel wool then oiled to keep things in check; the second looks like it was pulled straight out of a junk yard. Both juxtapose the OCD level of detail applied to cleaning up the rest of the bikes' looks, heightening the sense of functional nostalgia that makes all the Copenhagen custom builder's bikes unique. As long as the tanks have been gelled inside and the mounts are solid, this shouldn't lead to any short-term issues. Sure beats candy metal flake.