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.
Say, you can hang your backpack off your handlebars in those steep sections. Counterweight!