ubert767 wrote:As Vorpal said, they are cheaply available. I know them as "Chinese Laundry Bags, they are not very robust so I use them for two panniers each and secure around the girth with a yard or so of strong nylon 1/4" dia rope. Mine have survived several aiport baggage handler encounters so far.
Not very robust? Really? I've had two, the first had a handle rip off but only because I reinforced things with a luggage strap through the handles - which was then used instead of the handles by airport staff! Lesson learnt.
The second is going strong some eight years after purchase - it takes a set of panniers plus cycling shoes, bottles, pump etc with a bit of spare space. I chose a fancy pattern for mine to make it easier to identify on the carousel - the standard red or blue plaid patterns are so common, particularly with eastern European travellers!
An extra use while away has been as a porch sheet in the tent and as a dry seat - not bad for @ £5!