Gears, cranksets, and mountains....help!

[bike4ever]

A lower priced alternative is to replace the rear derailleur with a mountain derailleur. This would allow you to put a nice mountain cassette on your bike - something like an 11-32. You would probably also need a new chain. If you keep the parts you remove, then you can switch it back out once you return from the trip. This will probably be cheaper than a compact crankset/bb/possible front derailleur.

[Triskeliongirl]

I concur with bike4ever. In fact, I recommend an 11-34. That will get you up most anything, and you can still easily interchange it with a tighter cassette for flat land stuff later.

[OakLeaf]

What's your budget? I'll be the contrarian here...

A mountain cassette and derailleur is obviously the cheapest way to go, but you lose so many of the in-between gears that you're almost always pedaling at a cadence that isn't ideal for you. My legs aren't strong enough for a corncob any more (and honestly, I only ever put one on my race wheel, not the ones I used for training), but I definitely miss even one tooth in between cogs.

As for interchanging cassettes on the road, I don't know about that - maybe on a long unsupported tour you might want to carry a spare cassette and a chain whip anyway, but readjusting the derailleur is a pain, especially without a workstand.

[Starfish]

A mountain cassette and derailleur is obviously the cheapest way to go, but you lose so many of the in-between gears that you're almost always pedaling at a cadence that isn't ideal for you.

Well, I put an 11-32 on last year, and while I did notice some of the in-between gears disappear, I feel I have plenty of cadence choices. The resulting low gears really, really helped me do the climbing training I needed to climb 10,000 feet in one day for my event.

If I was riding across the country and doing serious mountain climbing, 4K, 5K, 6K feet for one pass, let alone a full day of climbing or multple passes, I would want those granny gears. That is where I am in my fitness and weight for all day climbing.

That is why I think it is so important to know the OP's background of training, fitness, strength, etc.