Black hub upgrade?
So what are they if not upgraded?
Polished silver, I believe (plain aluminum). The plain aluminum can show the effects of salt exposure and to keep it shiny, it must be polished periodically.
Thorn offers the option to buy Rohloff hubs in anodized red or anodized black finishes for an upcharge. These finishes are not only decorative, but protective. The anodizing process leaves the hub with a protective surface (the aluminum is etched under an anodic current in an acid bath, then color is imparted through either dyes or chemicals and the pores are sealed by effectively boiling during water rinse baths after). These are more costly, nonstandard options, so are subject to an upcharge and are considered an upgrade.
Rohloff hubs are also available elsewhere in "silver" (clear) anodized, red anodized, and black anodized. The ones on some German police bikes are green. I have seen blue and gold as well.
Best,
Dan.
