Cycling shorts come in two types: skin-tight Lycra shorts, originally designed for road racing; and baggy shorts, initially made for mountain bikers. Either is fine for commuting, and baggies look okay off the bike; liberal clothing policies may even allow them for work. Unless you're heading for somewhere like The Royal Ballet, Lycra (also known as spandex or elastane) is strictly for the bike.

Cycling shorts come in two types: skin-tight Lycra shorts, originally designed for road racing; and baggy shorts, initially made for mountain bikers. Either is fine for commuting, and baggies look okay off the bike; liberal clothing policies may even allow them for work. Unless you're heading for somewhere like The Royal Ballet, Lycra (also known as spandex or elastane) is strictly for the bike.

Lycra cycling shorts have a pad sewn into the seat. It's sometimes referred to as a chamois or chammy, because that's what it used to be: chamois leather. These days it's a soft, breathable synthetic instead, and like cycling mitts, some shorts pads also have gel in them. The pads in men's and women's shorts are shaped differently, as women have a wider pelvis.

Lycra shorts are designed to be worn next to the skin. That's right: no pants! So you'll need a fresh pair of shorts each day. You can wear underwear underneath them if you want, but be alert for chafing and skin rash caused by sweat if you do so. Conversely, if you do suffer any irritation, wear the shorts next to your skin and wash them with pure soap (no conditioner). Apply Sudocrem to your nether regions before putting on the shorts each time if need be.

Apart from the pad, Lycra shorts have few features. The waist is wide and elasticated and the legs have grippers to stop them riding up. Some shorts – called bib shorts – have stretchy shoulder straps. These are more comfortable than waist shorts as there's no waistband to dig in, and the shorts are held snug against your body and can't ride down. They do make loo stops more complicated.

Virtually all Lycra shorts are machine washable on either a 30 or 40 degree setting. Avoid using conditioner, which can clog the pores of breathable fabrics, and make sure any Velcro straps from other cycling garments, such as mitts, are done up to prevent damage to the Lycra.

Sizing varies from brand to brand, so try for size before buying. They're meant to be snug, with few wrinkles. If you're concerned that your bum looks big in them, don't worry: you can wear Lycra shorts under a skirt, tracksuit trousers, or baggy shorts – as well as under cycling tights in winter.

Baggy shorts have an integral pad, a padded short liner (which might be removable) or no inner short at all. They're still more comfortable than normal shorts or trousers as they're designed so that you don't sit on a thick, chafing seam when you're on the saddle. Baggy shorts are worn over underwear, a short liner, or Lycra shorts, as you choose. 

Since baggy cycling shorts were designed for mountain bikers, many look overtly sporty. Increasingly, however, baggy shorts for urban cyclists are becoming available. These have similar features – button or press-stud waist, zipped fly, pockets, durable and quick-drying fabrics – but in a more sober style.

Here's a cross section of Lycra and baggy shorts.