A Handlebar stem, sometimes referred to as a neck, is a clamping device that holds a handlebar in perpendicular arrangement to a fork. These three pieces, working together with a headset attached to a bicycle frame, are your steering system. The stem can either be Quilled or shafted or Threadless. Threadless stems are one of the most important cycling innovations to effect BMX. There is no respectable bike made in the last decade that doesn’t use a threadless stem. The typical threadless stem is an aluminum unit that holds the bars with almost infinite adjustment front to back and side to side. While the side to side is usually adjusted to parallel to the front wheel and frame, the front to back is arguably the most important adjustment on any bicycle. It is where you hold onto the bike, and is entirely personal.