I knew Peter was going to reply to that one! Just so everyone knows, I met Peter in Bangkok, he was coming from Tibet as I was heading that way. Peter crossed Tibet and SE Asia with one single t-shirt! When laundry day came, he washed it and wore it wet until it dried.
I am in favor of carrying extra comfort with me, so Peter and I have different opinions on the subject (which doesn't happen very often, right, Peter?). I believe that your body gets adjusted to whatever you carry. I carried up to 90lb of luggage during my tour around the world, and yes, hills were difficult at first, but they became easier and easier to the point where they were not painful anymore and I actually enjoyed them. My muscle mass just adjusted. No matter what you carry, your body gets used to it. A good anecdote supporting this is the story of one of my friends who hit the road forgetting one of his rear panniers after breaking up camp. He biked 2 hours before realizing that he was riding with 25% less weight. A difference of 15 lb. and he didn't feel it!
Tony mentioned Claude and Francoise Herve (I read their book, too
, Claude had 100 kg. of luggage on his bike (the most I ever heard of) by the end of their 14-year long journey and they were covering good distance, too. Of course he didn't start that way, but as they went along, he felt like he needed extra comfort and took the luxury to carry whatever they wanted, and his body adjusted. Of course, you don't want to go too crazy and I think that carrying 50% of your weight rule is actually a very good one. I also believe that a good touring bike should be able to handle 80 lb. just as well as 40lb. With all that extra load I carried, I ended up changing one pair of pedals, one rim, one derailleur, one tire, and a couple of chains during my entire 5-year trip - that's it!
I have a good story about the chair. A friend of mine joined us for a few weeks when we were in Thailand (shortly after I met you, Peter). He brought with him one of those low-folding chairs! It weighed 2 lb. and and was not very storage-friendly on a bicycle. We got to use it while he was with us and we really liked it. So when it was time for him to fly back home and he didn't want to carry it back with him, we hesitated, but decided to keep the chair. We were so glad to have it that we carried that chair with us for the next 2 1/2 years of our journey halfway around the globe. You can't lean against a tree or a wall and be as comfortable as if you were in a chair - no way. Benches are nice but how often do you find a camping spot with a bench? Peter is right - stretching is king - but a nice seat is so wonderful during breaks or while camping that in my opinion, it is worth the extra 2 lbs. However, CycloCamping.com now carries the Therm-a-Rest compack chair, which is much lighter and almost as comfortable.
Do you think this is worth 2 lb.? ...