Under the seat is actually a good idea for any throwover, I realised. Makes them mildly less nickable, and will say put when empty.

It looks a bit 'pikey' to me (insert 'pot call kettle black' emoticon here ;-) but the great thing is it costs next to nothing to try it out, plus you can easily repair or replace on the road. I think I'd get a general purpose [dry] bag the right shape and bung all your stuff in that and then in your harness. And I'd rivet on a PVC 'bellows' front and back and use short cam straps instead of the laces to do the tension. A bit more protection.
Look forward to seeing a finished version. You could chop of out of one of these (as BoB Andy used in a cradle on his CCM) though that would be box shape not curve. if you want the more common squarer shape 30L ones, I found car washes have them going spare (ex soap), but they get a bit wide unless you can heat and reform.

I know the problem of not having the luxury of anywhere to work other than a landing or kitchen, with limits what can actually be made but encourages lateral thinking. Where I'm staying now I'm renting a farmer's workshop which helps a lot.

I've also coming round to a plate. That pipe clamp idea was a wild goose chase - see green edit on earlier post.

The way I see it a plate replicates the rigidity of a welded 18mm rectangle which most OTS racks are based on, but can be cut from a slab of ally, plastic or wood and if thick enough, bolted straight to a bike subframe, eliminating an OTS rack.
You can then trim, drill holes or slots or screw/bolt on fittings as you like. Much more versatile than a rectangle of tube.

I happened to find a broken slab of chopping board-like nylon on a beach. A bit warped but at 10mm thick ought to be stiff enough to do the job combined with my half-finished metal frame.

Ortlieb Cycle pannier system brilliant - I can testify to that - but for me way too small for moto overlanding and as BYT says, probably not tough enough for moto forces without loop strap support. It's telling their QL2 moto version only clips to 16mm tube max - as if to discourage use with most OTS 18mm racks.


Ch