Originally Posted by
miamijim
Most sealed cartridge bearings can be serviced in a similar manner to conventional cup/cone bearings. If your hubs feel smooth all they should need is cleaning out of the old grease and regressing with some fresh grease.
I have never succeeded in cleaning out and regreasing a cartridge bearing without compromising the seals. Do you have a trick for that?
As the OP notes, these bearings are capable of handling a lot more load than they will see in bike use. However, most machinery that generates 16,000 rpm does not work in the weather and grit that a bike sees. Considering the relatively low cost, I would go with new units to insure good seals and protection from the elements. If the seals are truly intact, the grease should not even get hard with age because there is no way for the volatiles to escape.