the ring type is one sort .. Perhaps augment the elastic cord* with a non elastic cord or strap
to tighten the bag solidly .. pulling down on the upper hooks ..
I took a bunch of tours .. Beckman uses a belt and buckle tie down on Gordon's racks.
they never budge , until the buckles are loosened ,
solid also means the load is not moving on its own, on descents .. handling (at least my un Light Bike) is solid.
*or those screen door springs in n.17 ..
Last edited by fietsbob; 03-22-14 at 07:03 PM.