Simple the guy is taking crap, ive filled both panniers (48ltrs etc) and top box (52ltrs) and roll bag (40ltrs filled) + 15 stone rider, and toured england for 2.5 weeks, and done 2.5k miles. The luggage was not all really heavy but i would gues to say it was around 50-60kg or so, just like having another person on the bike with you. Only thing is the wind does catch the bike and upset it a bit but nothing you cant handle with a bit of muscle.