Originally Posted by
wphamilton
What you should do is, using the same bike, coast down a gentle slope (so that terminal velocity is not involved) where the surface is irregular, with the same bike and adding weight some of the times, and see what your actual speed difference is at the bottom.
Riding down a gentle slope is pointless, any cyclist will know that a loaded bike will out coast an unloaded one, basic physics.
Bumps be damned.
Try going uphill or accelerating over an obstacle, (like up over a curb etc.) extra weight won't help.
Its not quite as complicated as you think.