I've got a Topeak trunk bag with fold-out side panniers I've had for about a year now. For rain during commute I've just been wrapping a poncho around the bag and hoping it doesn't come off, but I see Topeak makes raincovers for their bags. I haven't been able to find a website that sells them (or any rain covers for trunk bags at all) so I thought maybe someone on the forums would know something about it. Does anyone know where I can find a waterproof bag with a tight elastic opening (damn it!)?