Bike Slut
Overly-intense bike riders, usually middle aged adults. Wear uni-sex spandex outfits in bright and obnoxious colors. Do not produce a legitimate reason for wearing spandex unitards or how it improves bike riding. May also spend up to $5,000 on a single bike, along with hundreds of dollars on special shoes, helmets, and special outfits (mentioned above). Ride in packs. Think they are cars. May ride in the middle of the street in front of cars. Sometimes they will yell at cars in an unintelligible biker language, probably something along the lines of how cars destroy the environment, that they are saints and are saving the world one bike ride at a time, or that the car is infringing and their personal bike-bubble. Occasionally mumble incoherent things about their heart rate.
Example 1

Person 1: Ugh that bike slut is biking in the middle of the road again, it totally thinks it's a car

Person 2: I know, and what's with the bright pink outfit it's wearing?

Example 2

Person 1: Molly is getting way too serious about biking these days, she's becoming a total bike slut