Writing from the company computer at work ?
(able to take at least 2 40L ortliebs)
Dont over think it .. get a bike .. any that will take a rear rack ..
Ortliebs upper hooks come with 2 inserts 8mm for solid alloy rod racks
11mm for Tubus or other racks of tubular metal.. and with no insert It's 14mm
CDN? visit a bike shop or the bike department at MEC.