Originally Posted by shants

it's a common mistake to say that "cartridge" bearing hubs are "sealed." a lot of people seem to think they're the same. of course, there is nothing sealed about a cartridge qua cartridge -- dirt, water, etc, can get in without a problem. for there to be a seal some additional measure needs to be taken -- a grease shield, etc. in many cases, the cartridges in cartridge bearing hubs directly face the elements without any seal, making them less "sealed" than many cup/cone hubs, which almost always have something that shields the bearings from water, etc.