Thats a great idea. It could be made to hang lower to hold panniers if you need to! Awesome!
Originally Posted by Luner
Yup, they're dry bags strapped to a home-made steel frame. It's a cheap, tough, waterproof system. I cut the back off the seat and made up a longer top rack too to carry lighter stuff
Below is a picture of the rack with no luggage (In the middle of a solo, two-hour extraction from a muddy oued).