Naturally, I've got a project lined up and ready to show.
There's an old adage that is often invoked WRT Cannonball: It's not how fast you go, it's how slow you don't go. To that end, auxiliary gas tanks are practically de rigeur on Cannonball, and I've seen quite a few different attempts at that. I'm a big fan of gravity-fed systems (since gravity never, ever fails) and so I prefer (by a wide margin -- don't try to talk me out of it) putting the gas tank on the rear rack. The weight isn't really that bad, but some reinforcement is a good idea nonetheless.
For Cannonball 2008, I had a very heavy, very overbuilt rack, heavily reinforced, holding up a four-gallon gas tank. For 2012, I've decided to go with three gallons instead, and have given quite a bit of thought as to how to support it.
I've opted for a lighter-weight rack than last time, using the Piaggio fixed top-case rack as my starting point. This particular rack is welded straight to the grab rail, with a short cantilever down to the support plate that screws into the back of the bike. In these pictures, you can see that I've added another
cantilever to it (the square tube) which pushes down on the frame farther down from the usual mount point.
I think this will work well, and it's many, many pounds lighter than my previous setup.
Oh, and before anyone asks: yes, I'm using the cut-off rear end of a GTS as a welding jig. I kept it when I scrapped a wrecked frame specifically for tasks like this.
The starting point
Shaping the tubing
Positioning the tube in preparation for welding
Positioning attachment plate
Cleaned up and bead blasted
The finished product
Mounted to my Cannonball steed
Three gallon gas tank on top (not attached yet)