feelinjunky wrote on 01/12/08 at 09:43:14:If you want a big and reliable, easy to install trunk, try the Jc whitney case. 22-1/2"W x 16-1/2"L x 11"H. I ride my bike to school everyday and it easily accommodates my 50-60 pound backpack (packed with all my books). It also adds more back support for the rear passenger. For $85, I think it's worth it.
I looked at the JC Whitney option. I decided against it for a number of reasons.
First, look at the mounting position. With the sissybar in place, the trunk itself (as well as its mounting plate) is pushed almost to the end of the luggage rack. In fact, the mounting plate extends almost 8" beyond the end of the luggage rack. That extension increases the torque stress on the rack mount. In otherwords, the farther back you mount the trunk, the more stress you are putting on the luggage rack. (think the principle of leverage)
Now by adding 50-60lbs into the trunk, you are stressing the luggage rack even more severely. Believe it or not, but every bump you hit in the road causes your entire luggage rack (and all of its contents) to bounce and deflect. (I noticed this while following a buddy who did the same thing with his Honda. With every jolt , his trunk would deflect a good 2 or 3 inches.) Every time you stress the metal it begins to fatigue and will eventually snap at that fatigue point... Taking the trunk and its contents along for the bouncy ride....
The only way to prevent the flexing is to add additional rigid bracing from the center-of-mass (the exact center of the trunk and its mounting plate) to the fender. It turned out to be more fabrication work than I wanted to get involved with.. That's why I ended up with the soft-side trunk.