Cycle shorts are made the give unrestricted movement whilst you're riding with the benefit of a soft seating area for additional comfort. The common material for making them out of is spandex (usually referred to under one of the many trade names - Lycra), cycling shorts have a fixed internal pad sewn into the ideal position for comfort and cushioning for both on and off road riding. The benefit of Lycra is that it stretches with your body and the usual 8 panel design means that there are no seams to rub you up the wrong way or restrict your movements.Lycra is a lightweight material and since there is only one layer of thin fabric, your nether regions will be kept cool on hot days - which is quite important.