Cartridge wheel bearings - is there an inside/outside? I'm replacing the bearings in a standard single speed wheel. I've got 6000-series bearings and I can't find info on whether there is an inside/outside.
Among bike parts manufacturers, the norm by a very wide margin is for there not be sidedness. There are exceptions, such as hubs that use sealed cartridge angular contact bearings, but I believe those always have different color seals on each side, and there's not very many companies that use them. And there are some cases such as Campy freehubs where you remove one side's seal before installing it.

As I understand it, the seal (closure) type code you see on the seal of a bearing describes the type of sealing used by the closure it's inscribed on. I believe that in all cases, if it says the same thing on both sides, you don't have to worry about sidedness.