I'm looking into buying a proper set of panniers that can handle a cross country tour. I am trying to keep costs down, and figure that one set of waterproof panniers for my front, low-riding rack (to keep clothes in, or anything else that can't get wet), and two larger water-resistant packs for the rear (to pack everything else excluding space for a small tent, sleeping bag, and ground mat which will sit on the rear rack) should be sufficient.
Any thoughts on that?
Also, what size panniers should I be looking for? I don't intend to overpack, but I would like to have some extra room if I had to pick up supplies/gear along the way.
I would like to know the minimum volume in cubic inches/centimeters I should most likely seek out for the larger panniers based on other people's cross country, or extended touring experience.
Thanks for any help.