In layman's terms a fixie hipster describes the average hipster riding atop a fixed gear bicycle often termed as a fixie. Although the heritage of fixed gear cycling dates to professional couriers, messengers, and track cycling. It is unclear how this style of cycling became popular with fixie hipsters. However, it is generally believed that owning a fixed gear bicycle has been labeled "trendy" within hipster culture.
Brett: Those are some nice decorations you got there Lars. What's the sprocket size on your bike?
Lars: umm 62....
Brett: Well, do you take it to the velodrome on the weekends? I bet that rig is pretty light. Real quick on the tracks!
Lars: uhh...I use it to go get a cappuccino.
Brett: Hey you might wanna put an additional braking mechanism on to decrease your braking distance. Don't wanna slam into things buddy.
Lars: Dude that'll destroy the minimalistic, bare bones aesthetic of my bike! It's a fixie bro! Besides I use my feet to brake for emergencies.
Brett: It's just for safety sake dude. Besides how the hell can you even ride a bike comfortably in those tight slacks and slip on shoes. God what a fixie hipster!