>>2066651Sealed just have an o-ring or the like between the case and the spindle to seal it, water still gets pulled in by the turning spindle but not enough to matter. If that water has an abrasive diluted in it, such as road salt, that abrasive starts grinding away the seal. Once the seal is eroded enough water and filth will get in to destroy those high performance cartridge bearings with their tiny balls and light grease. I average 2 years out of a sealed unit, generally it is in sorry shape during the second winter but I tolerate it as long as it is not noisy so I can have a fresh BB for spring.
Cup and cone use larger balls which don't care as much about a bit of filth and are packed with a good amount of a heavy grease which keeps the filth and water away from the races. In the case that enough filth gets in there that it starts affecting performance or water has washed away much of the grease, you just clean and repack. All that heavy grease will get you through most any winter.
What you can't quite see in this picture is that this BB has o-rings in the cups, so are sealed as well as most sealed BBs when combined with the sleeve. It has a bit more friction than the high performance cartridge bearings in sealed BBs but not enough for me to care about and considerably less than salt filled BB it replaced.
During the shutdown when everything was sold out and I needed a new crank, I ended up switching to an external BB, those things suck for winter, lucky to get get one winter out of them. I swung to the other fence.
