The headset, that hidden workhorse that without it, steering would be next to impossible if not terrifying. The headset also takes the brunt of forces acting on the fork as it is between the steerer and the frame. Suspension helps mitigate this, but for the rigid crowd, checking the headset once a year is a good idea due to the forces it takes.
Headsets themselves aren’t complicated. Two bearings allow the for to turn freely within the steerer tube of the frame. The only real differences between headsets are materials and the bearings. Nicer bearings=smoother movement. Some bearing configurations are also engineered to be free moving under lateral load, or in a turn. Lateral loads can bind up a bearing, put in practical use, I have yet to really experience that. Besides, in turns, lean usually does most of the turning as opposed to actual turning of the handlebars. Let us look at the parts of a headset after the break.
Remember the difference between a threaded for and a thread less fork? If not, check out the article on the rigid fork to refresh your memory. Here you will see a rudimentary drawing of a headset, exploded in all its glory.
As you can see, my drawing skills are far behind my mechanic skills. But you should get the picture. There are different kinds of headsets such as zero-stack, internal, and tapered. They all basically function the same: the fork steerer is inserted into bearings that are inside the headtube. This is what allows the fork to turn! Not rocket science. Yeah, those bearings aren’t exactly drawn correctly either, they’re supposed to fit inside those cups.
I hope this information helps you figure out how a headset works. In a later post, sometime later, I may go into how to rebuild one of these. Until then, you have been armed with more knowledge.