Waterproof Bicycle Trunk Box
When the zipper on my fabric trunk bag broke, I decided not to replace it. It didn't hold much and my stuff got wet when it rained. I switched to a $6 3.1 gallon Rubbermaid Roughneck tote. OK, it isn't fashionable and it doesn't have those flimsy, convenient light duty side bags that could be unfolded from my old fabric bag, but I have found the Rubbermaid tub to be very valuable when bike touring.
It's light.
It's waterproof.
It's durable.
It holds a lot.
It's compatible with my panniers (it was a PITA to attach both the old trunk bag and panniers, since both required access to side rails.)
It's useful as a utility bucket, laundry tub or wash basin. Very convenient when bicycle camping.
Additional items can be loaded on top of the flat, sturdy lid.
Supplies
Rubbermaid 3.1 gallon tote
Three 18" medium duty bungees
Drill Holes in Handle Supports
Drill 1/4 inch holes in each of the handle supports.
Bungees
Lay two 18 inch medium duty bungee cords from front to back underneath rear rack.
Attach Bungees to Holes
Hook the bungees into the holes on the handle supports.
Extra Security for the Lid
Use another bungee to keep the lid extra secure.