-Ortlieb pannier spares,which you can buy. I cannibalised some ruined bags which used the 'QL1' system
-Corrugated plastic sheet sometimes called correx - I bought this from a framing wholesaler in Birmingham for like £3 or £4
-2 x Alpkit 20L dry bags. I Actually went to their factory/shop and they are really nice

All you do is 1) cut the correx sheet to the right shape to provide a backing for the bags. I calculated that 28cm wide for the backing would give the largest volume for 20L dry bags. The height of this is up to you. 2) Cut an oval shaped base - estimate from drybag dimensions 3) wrap sharp edges of correx in duct tape 4) determine best place for QL1 clips for your particular rack - as low and far forward as possible, but make sure to avoid heel strike 5) screw the QL1 clips through the backing and through the drybag material using ortlieb screws. Having someone to help you makes it much easier to get the bag positioning correct.

Next to an Ortlieb bag

Pair of bags. One filled, one empty and with a 'fiber flare' light on it.

Weight of one bag





On an electric bike



The base of one of them

The backing when the bag has been assembled.
I've used them now for a couple of months and they they work. Don't really notice any difference between them and the Ortliebs. Only thing I might do at some point is to add a shoulder strap to them.
The final weight for each bag is 431g and 856g for both. A whopping 1050g saving over my Ortlieb bags
