Originally Posted by
FBinNY
You're 100% right that typical cup/cone hubs and BBs had lousy or no seals and water entry was common. But that's only half the story. Sealed cartridge bearings also let water in, but there's a big difference in how the various bearings let water out. Old stuff lets water escape very easily, whereas the lip seals of cartridge bearings do a good job keeping it in.
This is why we see so many rust failures of sealed cartridge bearings. In fact, most professional mechanics with decades of experience will confirm that rust failures are more common on cartridge bearings vs. the primitive stuff.
You are incorrect about the ability of the cup and cone bearings to shed water once the water is inside the system.
If the water gets in, carrying all the dirt and grit of the world, it is quickly whipped into 'mayonnaise' or an emulsion of water and the oil/surfactants in the grease. Emulsions of this kind can be very difficult to break. They will remain as an emulsion just sitting around for days, weeks, months or forever. Even if the emulsion breaks down a little with time, once you start pedaling, you just stir up the mixture.
On the other hand, cartridge bearings...even cheap ones...are so much better sealed than cup and cone that water infiltration is practically nonexistent. I've even done immersion tests on both types of BB (aka stream crossings). With the cup and cone, you
have to rebuild after any stream crossing. The same is not true of sealed units.
You may see rust failures of sealed cartridge bearing BB but I haven't seen, nor heard of, any. At the shop that I volunteer at, we see lots and lots of rusted loose bearing BB but I've not see a single sealed unit that's even all that rough.