Purchased a set of luggage (day bag ang the larger bag. Both bags slip over the back rest and the rear bag rests on the rear 5 bar luggage rack. My question is that the rear rack is only rated for ten lbs. Does anyone know why so light? Seems the luggage rack is rather sturdy. Also if the large bag rests on the rear seat it is rated for 25 lbs. Anyone with any experience? Thanks Tom C.