>>1891326looks nice. i heard back from the seller. these weights are probably including the straps because i've seen 470g and 210g listed in descriptions. this is a good chunk of weight difference for a similar size bag. the polyester bag will probably require modifications to make the straps work the way i want them to, it doesn't have the bottom rear mounting point like on my trafellows bag, but oh well.
>>1891329this will be for carrying mail parcels (i sell online) so i don't have much choice. the boxes/envelopes will usually be almost empty with some bubble wrap so they won't weigh much but they'll take up space inside the bag. i plan on using releasable cable ties with handlebar tape glued on the inside of the cable ties and with clear duct tape on the frame to try to protect the paint. with the releasable cable ties i don't think it will take too much effort to take the bag off for leisure rides or for carrying smaller loads in something like a messenger bag, chest sling bag or my jacket pockets. this will be much lighter and more aero than a rack with pannier bags for instance.