Andrew R Stewart 

James- Like most all bike systems a periodic take apart, cleaning, assessing of wear and reassembly (with original or replacement pending assessment) with proper technique and lube is all that's needed. A lot of words to meant maintaining the bike. Of course no water exposure means that far less grit/grime will be collected at the inner seal of the actual bearing. Remember that bike bearings have had non contact seals (what most often call dust caps) for decades with these bikes doing just fine is taken care of. Of course in today's world of big marketing claims and little "value" of care during the life of a component (meaning parts are now considered to be disposable, what with development/marketing cycles happening so frequently) the idea of extending the life of parts is less important then how to install new ones. Andy