Now ley's see, 30 gallons of gasoline weighs 240 lbs. Add 200 + pounds for the weight of a grown man with equipment and you are putting in the neigborhood of 450 to 500 lbs. on the bike frame. I know the NVA and Viet Cong used bikes to carry heavy loads, but they were specially strengthened steel bikes, not the lightweight alloy's in use today. They also were not ridden, they were pushed. I'm no expert, but I think you would wreck your typical mountain bike in short order subjecting it to a load like that.