Guyon that's a great surly rig. I am a devout mountain and road biker, cross country for both. Easiest way to do it I find is a trailer, doesn't affect the balance of your bike and to me seems to be the easiest for carrying gear. You need craploads of calories, a good balanced diet to be able to push all day, day after day. That said if you stay hydrated and are on a well balanced diet you can burn 1500 calories an hour all day long. Biker Butt is usually gone within the first two weeks of the season for me, but you're going to want to take a look at BodyGlide or some other form of lube for your asscheeks, so they don't feel like you've been sitting on a belt sander all day. Biking in my opinion is by far the best way to burn fat, you do it so fast with limited stress on your body plus you get to see beautiful country, and the personal satisfaction of covering huge distances under your own power. Do someone else a favor and find a charity to ride for too, you can spend a few hours raising grants and that way raise thousands of dollars for some organization.
