A brand new $600 bike is a piece  a ..
A fixer upper is the best cheap bike.  They made some good solid bikes in the 90s.  Parts are cheap for the "old beast" as well.  11 speed cassette $400, 10 $100, 9 $80, 8 $30, 7 $20, freewheel $14.

If your not afraid to get a little grease on your hands, you can ride a bike for under a $100
Bike coops exist to help people rejuvenate old bikes.
http://www.bikecollectives.org/wiki/index.php?title=Community_Bicycle_Organizations&Itemid=100015
Example:
$40  -  97 moongoose from value village
$5    -  used stem
$28   -  Ergon gp5 grips from REI garage sale
$7     -  break cables
$5     -  used seat from bike coop
 

Sir, the Pan America highway is the main truck route from North America to South America.  All the trucks travel that route.  Perhaps you could find A more interesting and scenic route.  

You will need to purchase many bike parts in route.  What bike parts are most commonly available in route?  26 inch tires?  Cantilever brake pads?  Square taper bottom brackets? etc... ..

Alternate routes... http://bicyclenomad.com/route-information/  They started with trailers and piles of stuff, finished with much less.
http://www.ridingthespine.com/

I bought a Fargo in March of 09.  A fine machine to be sure.  I recomend 26er for your trip.

http://www.postholer.com/gmap/gmap.php
could be of use to someone
http://www.postholer.com/

Thanks to our man in the North for explaining the race to us

¨Thanks for your great commentary Sean. ¨

Which tent is more reliable than the others?
Which socks are better?
etc
My experience with wool socks...  ..
The higher percent of wool the better.  Medium cushion Smart wool socks last a while. The thinner ones get holes in them to quickly.   If they say 62% wool I don't buy them.  78% seems good.  I got some at 88% wool, which were a little less comfortable, but a little warmer when soaked. 

Wool jerseys are about the same.  The thinest ones wear out to quickly. The thicker ones last for a while. The thin Ice Breaker GT shirt had a short life span.  The thicker Ice Breaker shirts last quite awhile. 

I wonder what the criteria for a tent should be?   Free standing? Light weight?  Storm prof? Anyone get 200 nights out of a tent?

after dark glasses could keep a tree branch or other unseen thing out of your eye

Any body familiar with the area around lake Chelan?  Is there a way to get from Leavenworth to Stehekin along the west side of the lake?  What about North from Stehekin to State Route 20?

any 29er tire made
Wtb 2.55 weirwolf tires fit a Flow
Racing Ralph 2.4 fits a Flow
Surly says their new 3 inch Knard will fit a Flow
maybe they did not say that ops

What fork  fits 3.4 inch 29er tires?

"But it's pretty rare to need/want a tire that wide on a trail bike. What are you planning on doing with your fat rubber?"

If you encounter sand along the trail.  Some times the trail turns into a dry creek bed for a few miles. A 2.55 is not quite enough for a river of sand.  

free bike maps in portland
Visit pioneer square in the center of down town.  Under the Star Bucks and behind the water fall. 
Multnomah County map, Columbia River Goourge map, Portland sectional maps, N, NW, SW, SE. All free.
I forget if it is the N or NW map that shows Forest park.  The largest urban park in the USA has many trails. Some for bikes Some not for bikes.  Basically the farther from the zoo the less regulated they are.  The Lief Erickson is a good afternoon ride. If you decide to poach the Wild Wood Trail on your way back to town watch for slippery wooden bridges after blind corners.  People that tumble there usually switch to flat pedals.  North of the Lief Erickson are phone line roads.  They go on too... ..  who knows, Astoria perhaps.

I am in southern Mexico at the moment.  I don't miss the rain. 

 Combination of light rail and bus could get you to Estacada Oregon for $2.25. From there head up 224 along the Clackamass river.  From Estacada to Klamath no one should care where you camp.  Dispersed camping is legal in the National Forests.  The camp grounds are cheap.  Most likely free or not checked in winter.  If anyone else braves the weather, you will probably get free food and coffee.  The bike shop in Sisters Oregon can provide you with trail maps and and info for a crazy off road adventure.  Bend Oregon has trails every where.  You can get most of the way to klamath off road.  Get The IMBA maps from the LBS in Sisters.

After leaving Portland the risk of bike theft is 99% reduced.  Few if any stores will object if you bring it in.

Bike theft culture
Due to drug culture mostly
There are professional bike thieves in Portland.  
Bikes are stolen in broad day light and sold at used bike shops with altered serial numbers.
Handel bars and seat post are removed out side of stores, in 1 minute.
I ride a $30 bike to the library and the store.
I do not park a $3,000 bike on the side walk in Portland. not for 1 minute.
Seattle is just as bad.  San Francisco leads the world in most stolen bikes.

The further in advance you buy your ticket the cheaper it is.  Last minute tickets are silly expensive. 
Your ticket has a cash value if you change plans.  You can change stations.  They will trade your old ticket and cash for a new more expensive one.
Amtrak boxes are huge. The fee went up to $25.
Un assembled bikes arrive at bike shops in small boxes.
I have partially disassembled my bike and used one of these as a carry on.  Not all stations have full service. Klamath does.
Check to be sure, Is it 2 pieces of lugage as carry, and 2 checked bags .  One small bike box, one backpack, And 2 wheels in hand went unchallenged.
Hot water is free on the Starlight. Everything else is expensive.  Bring instant coffee, oatmeal, cup of noodles, etc.

black bear "stalking"
Black bears do not stalk people.  It is possible they wanted to eat their garbage.  It is difficult to get a black bear to attack a person. If you decide to attack the bear, kick it, hit it with a stick etc, it might fight back. Standing between a mother and a young cub could on rare occasions force the mother to defend.  If you see a cub alone turn around and look for mom, she is not far away.  If you find your self between the 2, move sideways.  Do not get closer to mom, do not get further away.  Move slowly, do not run.  Let mom walk to her cub. Don't block her path.

Mountain lions have attacked people on rare occasion.  It was mostly a case of mistaken identity.  They will avoid you if they can.  They have terrible eye sight.  Stand up straight. don't bring meat into the forest.  The smell of blood, and a person bent over, might trick the half blind lion into thinking you are a wounded animal.

The only true danger in the Ozarks is a drunken fool.

I spent the last 3 weeks walking isolated trails and visiting ruins in Guatemala.  No monkeys beat me up, and no jaguar pounced on me.
One foggy morning I was hesitant about climbing to the top of a crumbled pyramid.  Looked like a long ways to fall.  Would I get hurt if I took a tumble.  A couple of 6 year old barefoot Mayan girls shoved me aside and climbed past me.  

nerves anticipation is a natural part of life. 
 now go have a nice day on your bike.

tubeless in Oregon, not really.  Occasional flat, yes.  Goatheads, no. 
http://www.universalcycles.com/ has the supplies you need.

More clearance for a fatter front tire if you want it.
Surly is creating one now. http://surlybikes.com/blog/post/wherein_we_attempt_to_answer_your_krampus_questions
read the second to last post here for an idea
http://forums.mtbr.com/29er-bikes/schlumpf-cranks-690115.html
The upper bottle mount on the fargo is by far the most convient.

under frame bottle mount can be desirable