What a sissy bar duffle has to do
Why the volume moves
A fixed bag is wrong twice. Too big for a Saturday and you ride with fifty litres of air, and the load shifts every time you brake. Too small for a week and the tent goes on the pillion seat.
The roll-top is the adjustment. Three turns and the Nomad Duffle holds 45L; leave it open and it takes 65L. The bag closes on whatever is in it, so there is no slack to absorb.
Why waxed canvas and not leather
A full leather bag of this size weighs on the subframe, soaks up a downpour and takes two days to dry. 16oz waxed canvas sheds water on its own, dries in an afternoon and takes a scuff without recording it. The leather is where leather is right: five full grain straps that take the load, and a reinforced base that meets the fender.
Wax wears where the bag folds. That is the point. Re-wax it once a year and the shell outlives the bike.
Why straps and not a bracket
Brackets fit one sissy bar. Five straps wrap any bar of any diameter, round or flat, tall or short, and pull the bag against the backrest instead of hanging it off a hook. Nothing to bolt on, nothing to leave behind. Off the bike it is a duffle: the shoulder strap clips to solid brass and the whole thing walks into a hotel without looking like motorcycle luggage.
What fits inside
At 65L: a two-person tent, a sleeping bag, boots and a week of clothes. At 45L: a change of clothes, a laptop in the padded sleeve, and the two bottles in the outside holders. Two zipped pockets inside for what should not migrate, one outside for papers and the wallet you need at the pump.