Bike: Tricross Comp
Rack: Blackburn Expedition
Retention system: 4-hook 12' bungee net.
Backpack: my teenager's hand-me-down WHITE! Roxy
Wateproofing: garbage bag tucked into side compartment

The beauty of this system is its flexibility - hook the net in various point to accomodate everchanging fullness of the backpack, and mine goes from bursting at the zippers to like two verrry large grapefruit. Fringe benefit - serves as a fender ;p). Second net for front rack (this one is Specialized) is inside the backpack. These nets compress to the size of tennis ball.

Ride Safe

SF