When bike camping, the sleeping bag is one of the essential pieces of equipment, providing much-needed warmth and comfort. As a piece of luggage, you want your sleeping bag to be as packable, light and durable as possible. Modern "mummy-shaped" sleeping bags are perfect for this. The type of filling and temperature range can, however, have a dramatic effect on the packed size and weight. To keep both within limits, you should think carefully about how warm the sleeping bag is: you don't want to freeze, but being too warm is also unpleasant. Down sleeping bags are lighter and can usually be packed noticeably smaller. Sleeping bags with synthetic filling are better for humid conditions and usually cheaper.