Re:
Oh sorry, didn't see your point about spares...I guess when you need them, you really need em right? and it's not exactly heavy to carry a couple of rings of metal...I don't know what do you think? Do you think it's unlikely that they will wear out at some point on a 15,000 mile trip, a lot of which will be on rough terrain?
I don't know how sturdy headset bearings are really, I've had a few freak out on me, but they've always been second hand so I have no idea how much of a beating they've had!