Makro maybe you could consider using an internal combustion engine. I have a recumbent with a Subaru 1.6 hp engine on it. It gets 34 miles on its 21 ounce tank. That is running at a very high speed and I have stuffed steel wool in the muffler to make it quiet. You could easily and cheaply build a bike that would get 120 miles with very little gas. Possibly a half gallon. It can't be used everywhere however can be used to get great distance on the side of a road. To me that makes more sense than trying to use heavy batteries to go the distance.