You'll see two types of riders on the road - those wearing regular street clothes when riding, and those wearing specialized bicycle clothes. (The latter include a subspecies that looks like a moving billboard.) I started in the first category but have been completely converted to the second. This chapter considers each piece in turn.
The fundamental principle for bicycle clothing is layering. If the weather gets colder or wetter, one does not choose a thicker material but adds more layers. The advantage is that this makes it easier to adjust to changing temperatures without having to carry a complete set for every temperature range, and it is faster to adjust by opening or taking off just one layer. Bicycle riding requires much more attention to just the right clothing - too warm is just as bad as too cold.
Another principle is tight fitting. A baggy jacket not only acts like a braking parachute but also lets cold air get closer to the skin, which makes the wind feel much colder because sweat evaporates directly on the skin. One function of bicycle clothing is to keep the skin dry by transporting sweat to the outside, where it can evaporate without cooling the body too much and without soaking the clothing.
See also an article on "pants"
