I'm thinking about making a frame bag for my 25" 1985 Raleigh Portage 650B touring bike. It still has the original racks front and rear with a 24L Carradice Camper longflap saddlebag resting on the rear rack. My hiking baseweight is currently around 10 pounds; from spring to fall I can basically get everything in the carradice bag except water, shelter and pad. With a big frame bag, I think I could ditch the front rack and two water bottle holders.
I'm looking for suggestions on how to construct the bag, and what type of material to use.
If I use the whole internal space it would be huge. Will a frame bag that big work? I would think a bag that big would need some partitions and perhaps some support. I was thinking of using my roadmaster pump or shelter pole as a horizonal support in the middle. The pump would work better I think because of the notches it has to fit against frame tubes. My shelter pole is about 1 cm shorter than the pump.
Here are a few photos:
Image of pump where it would naturally rest:
Image showing 2L Platy, Tarptent Contrail and NeoAir relative to frame: