The Dirt Bags are a cheap way to put some Luggage on the XChallenge. Saying that I would not spend the money on them if you are going to travel with them.
Racks are not up to the task
Zippers clog with dirt and can be very frustrating.
IMO get something waterproof with roll tops.
I like the Madigans , Andy Straps, and the Wolfman Luggage.
ADV Relay Rider 08 (The Texas Connection)
Ride Pooie Ride
Don't stop riding until you get to the crash , you might save it!