[Rune Son of Bjarne]

This subject has been well debated on the downs. . .Many is of the belief that there must have been other ways and that Gandalf must have known at least one, but I don't think anything was ever concluded.

I personally think that there would have been other ways, but I doubt that they would have been alternatives. One could have spend ages searching for passes over the mountains and they would probably also have been guarded, but probably only by orcs.