Question

why is it advised to tie the luggage in the vehicle

Answer 1

: A luggage is usually tied with a rope on the roof of buses. ... Similarly, when a bus suddenly starts, the luggage on the roof of the bus tends to continue in the state of rest and hence fall down from the roof of the bus. Thus, to avoid the falling of the luggage, it is tied with a rope on the roof of a bus.

Answer 2

 Bike bags are invaluable for carrying your gear on any cycling excursion, be it a day trip through the countryside or a round-the-world bike trip. In the past few years bike bags have largely managed to rid themselves of their image as something not used by serious (read: cool) cyclists and have become quite popular. For good reason: They are immensely practical, especially since these days manufacturers are making a large range and different styles of specialized bike bags for every conceivable use.