Originally Posted by
msincredible
Hmmm, possibly the stempost.
Also, I should probably define "heavy backpack". When I have it on (with my laptop and portable drives and all the stuff I need for work) it's typically around 25 lbs, which is about 25% of my body weight, and it is larger than my torso. Guess that might have a significant effect.
I've got a Rixen Kaul/Klickfix rucksack and bracket that attaches to the seatpost. With my laptop and other bits it can be pretty heavy and so far the bracket seems okay with the weight. And when commuting, the Respro rucksack cover is a great safety feature as it lights up like a Christmas tree when headlights shine on it.
http://www.dotbike.com/ProductsP2121.aspx?TRACK%3dDPL
http://www.dotbike.com/ProductsP2122.aspx?TRACK%3dDDI - this is the new version of the one I have