Googles
Also, do not forget about the googles, as they are a crucial part of a steampunk look, especially on a bike.
Check out these Vintage Victorian stele googles that have a magnifying glass. They look amazing, and as if they are from a real steampunk world.
Different color lenses are also a way to go, like these purple ones. The black finishes and the overall Victorian style with bronze details are truly reminiscent of a world where steam is the predominant source of energy and power.