Originally Posted by
FBinNY
Don't be fooled into believing thatmost sealed BBs are actually sealed. The sealed bearings used on most are made for things like electric motors, and the seals are dust seals, not weather seals (you don't run electric motors out in the weather).
That's if it has cartridge bearings. Many Shimano BBs are sealed and seem to last. They are purpose-made, not built with electric motor bearings.