Usually an inner, large city courier that delivers mail (packages) by bicycle. Can be known as "messenger." Messengers can be found riding fixed gear bicycles (fixie) or any variety of bicycle suit for timely travel. They can be seen with a large "messenger bag" style backpack, radio/cell phone, and bike lock.
Messenger culture includes fashions that are functionable before fashionable, meaning that the styles of clothing messengers tend to wear are suited for purpose and not pleasure. Messengers are exposed to inclement weather including heat, rain, snow, cold, and ice. Pants, if worn as opposed to shorts, may either have the right pant leg or both pant legs rolled up, or cut shorter so as to not get caught in the crankset.
Fixies are usually customized or built from scrap for personalization. It is common to see brightly colored bicycles for visibility purposes. Handlebars may be cut short to produce a narrower, or more streamline messenger so as to allow the rider to pass between vehicles in slower-moving or standing traffic. Brakes may not be present on some fixies, but some city or state laws require it, so messengers may only affix one to the front tire.
Messengers may also be seen taking part in spur-of-the-moment or organized "alley cat" races which simulate the duties of the average day of work. Winners are awarded spoke cards which are placed in the spokes of the rear wheel.
"I hired a bike messenger to deliver a gift so it won't be late to your party."
Someone that dedicates there life and money from their paycheck in to their fixed gear bike so that they look cooler, also they mostly hang out at bars and or bike shops. Sometimes you can find them at random parties with people they dont even know, they sometimes ride in packs just to make them selves look much much cooler.