what component makes it possible to spin the bars completely around?
Not that all teenagers are evil mind, just most of them.
Try this changing my bike so I can do barspins
"...the people get the government they deserve..."
And you rarely, if ever find them on mountain bikes. It's really a BMX thing, although you might find some of the Urban type bikes with a detangler.
'If Wal-Mart sold parachutes, who would jump?' Frank Havnoonian (quoting his father) Drexel Hill Cyclery
It's called a long cable or hose, doing it with a geared bike is next to impossible though. My bars can spin two rotations either way with a full length hose(uncut) for my rear brake, I ride without a front brake.
Nemesis Project Cycles
My guide to singlespeeding