Originally Posted by
tang1223
This is just ignorance with simple physics. The lower your center of gravity, the stabler is your ride. Not only does a heavy bag on the handlebar raises the center of gravity of the rig, the bag catches more wind and impacts the steering. This can be a serious problem with strong cross winds.
Weight/mass is what affects center of gravity. Not bulk/volume.
You can have a bulky bag on top with lighter stuff - like clothes, sleeping bag. If your weight is concentrated low this will still ride OK. Yea, the heavier your stuff "up top" gets the worse the handling is.