Sorry, but I didn't get it. Yes, you can bid 0 with with anything whether you have 2 cards of something or none. From the rule book: The player with the leader token announces his bid and destination he can bid any number he can pay,including 0. It works great if everyone passes and you don't have the card you need to travel to that destination.
If I have 2 mountain cards in my hands, is it possible to bid 0, or I have to bid at least 1 ? Resuming, I only can bid 0 if I have no cards for that road type?