I use to use that trunk. I stopped after destroying 2 racks.

The first was a Canadian Tire Cheapie (not sure what kind of metal it was), and I had it on my bike for a couple of years. It bent the supports after about 2 months.

The second was an Axiom Odyssée (load capacity 70 kg !!! ~ 150lbs). Part of the reason I got it was because of the carying capacity (far above what I cary normally - towel, work clothes, lunch, mini pump & mini tool kit). After one month, it snapped as well. I was definately happy about the Lifetime Guarantee.

I think part of the reason this trunk was bad for the racks is that it sits so far back. You can't really change the position back too much, as the bottom is curved for the last 1/3 (unless your rack is also curved down). Sitting too far back just lets the trunk act like a big lever, putting a lot of force on the rear rack stays with each little bump.

Hopefully you have a better experience with yours than I did.

Sprocket