If I haven't been on a loaded bike for a while, it feels bad for the first few minutes. Best not to try to get the jump on a truck. After a few minutes it all squares away. Most recently I moved my CG up conciderably on the front rack, same thing, it was fine after a few minutes. Doubtless there would be some extreme point above which it might be dangerous, but I haven't been close with my regular gear. I kepe my tent and sleeping bag on the rear rack, so I don't care for a bag there, but I guess others buy them.