I bought my first mountain bike about a month ago, both for recreational use as well as to use as a commuter across my college campus. Well over the past few weeks we've had some pretty nasty weather, and even though I've done my best to wipe down the bike after riding it, the chain has become really rusty. I'm pretty sure that's the only part that is actually rusting, but it is getting nasty rust gunk all over the cogs and other parts of the drivetrain. Is there anything I can do to repair this other than buy a new chain? And also, what can I do to prevent this from happening again? I'm not overly concerned about having to buy a new chain if that's what needs to be done, but I don't want to risk damaging other more expensive parts of the bike.