Haste de Bicicleta

Bicycle Stem https://www.alibaba.com/Bicycle-Stem_p100001410?spm=a27aq.13891069.1148563840.14.1835229fShA0rS 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,[1] a stem's design belongs to either a quill or threadless system, and each system is compatible with respective headset and fork designs. the stem inserts into the steerer tube, which is threaded and does not extend above the headset.the stem clamps around the steerer tube, which is not threaded and extends above the headset. Threadless stems, the newer of the two styles, are widely popular and have displaced quill stems as the industry standard on sport bikes. Threadless stems feature a modular design where the stem clamps around the outside of the top of the fork steerer tube that protrudes above the headset. Threadless stems are commonly available in lengths up to about 130 millimeters (5 inches). With threadless stems, a "star-nut" is driven down into the threadless steerer tube and held in place by two barbed flanges. The top cap bolts into, and pulls against, the star-nut, thereby preloading the headset bearings. (See: photograph of Star-nut) Newer model forks, with carbon fiber steerer tubes, use an expander plug instead of a star nut, which once installed serves the same purpose as the star nut, but will not damage carbon fiber forks as a starnut will (by design a star-nut digs into the surrounding tube, which, while safe with aluminum, can weaken carbon fiber to the point of failure). Special adaptors may allow a threaded fork to receive a threadless stem.