On a dirt jump bike. How does the stem fit to the headset.?

Question

I know it seems stupid but i cant get my head around it. If possible has anyone got any diagrams as im not used to working with headsets.

Answer 1

The stem doesn't fit to the headset, really.  The stem clamps around the steerer tube that comes up from the fork, through the head tube in the frame.  The headset sits inside either end of the head tube.  

If you're talking about a really cheap bike or an older bike (more than 10 years or so), the stems they used back then actually did go down into the frame, and if you didn't know how those systems worked, I could see how it would look as if it went into the headset.  

A great way for you to learn all the bike parts and how they fit together, etc. would be to visit the "repair" help section at the Park Tool website.  Great photographs and instructions on how to do everything properly, and it shows various systems for all the parts, too.  check it out:  http://www.parktool.com

Hope this helps some...ask again if you need anything else!  :o)

Answer 2

Well, first you should identify the parts:

On top of the stem is a cap with a bolt through the center, This is called a "preload cap".

The preload cap is held by a "star nut" that is installed semipermanently into the fork steerer tube.

The stem also held onto the fork steerer tube by a pinching action using as many as 4 bolts, usually located at the back edge of the stem.

Below the stem there are often a few "shims" that take up some space between the stem and the headset. Immdeiately below these shims is a tapered shim that fits into a mating part in the headset.

So, to install a stem... install the fork, place the tapered shim into the headset, install the necessary shims, install the stem making sure there is at least 4mm (1/8") between the top edge of the stem and the top edge of the steerer, place the top cap on, s***w the bolt down ONLY UNTIL THERE IS NO PLAY IN THE HEADSET, straighten the handlebars, and tighten the stem.