The stem is the component on a bicycle that connects the handlebars to the steerer tube of the bicycle fork. Sometimes called a goose neck, a stem's design belongs to either a quill or threadless system, and each system is compatible with respective headset and fork designs:

• Quill: the stem inserts into the steerer tube, which is threaded and does not extend above the headset.
• Threadless: the stem clamps around the steerer tube, which is not threaded and extends above the headset.