Compression systems

A headset is more or less the two bearings that allow the bars and fork to pivot from the deck.
It’s very important to take good care of your headset to make it last. It’s possible to clean it by removing the shield that protects the little balls inside. Clean it by removing any dirt and reapply same form of lubricant (such as oil,) or else the balls can grind away at each other and reduce the quality of the headset’s performance.
Make sure to have your headset really tight. If you don’t, movement in the headset can deform if and shorten its lifespan.
There are two main types of headsets: Non-integrated headsets are starting to disappear from the market, as they are intended for entry-level decks and need to be manually installed into the head-tube with applied force.
With an integrated headset, the bearings can simply be placed inside the integrated cups in the deck’s head-tube, and you’re done.
Beware! Sometimes the bearings on non-integrated headsets are sealed, making them look like integrated headsets, but they are not. Don’t use these on an integratde deck or you could damage your head-tube.

Non-integrated headset installation:

1 : headset cap
2 : compression ring
3 : headset bearing
4 : headset cage
5 : deck headtube
6 : fork
7 : crown race

Non integrated headsets are made up with a Crown race that goes on the fork, 2 bearings, 2 cups, one compression ring and one top cap.
First install the Crown race on the fork and then put the headset cups in the head-tube. A special tool is available from many bike shops exists to make this easier, but you can just use a hammer. Use a wood piece or something soft in order not to deform the cups.
Then place the bearings in, put the fork into the head-tube, put the compression ring on the top and the top cap above it, and your headset is installed.

Integrated headset installation:

1 : headset cap
2 : compression ring
3 : headset bearing
4 : deck headtube
5 : fork
6 : crown race

In this case, everything is made easier.
Just put the Crown race on the fork (some forks have an integrated Crown race, so you don’t need it.) Then put the bearings in the head-tube, followed by the compression ring, and top tap. Then you can insert your fork.
Beware, the compression ring is a very important component, so make sure you don’t have any movement in your setup. Without it, you can tighten as hard as you can, without reducing any movement.