Now that we have gotten through the wheel adjustments, lets take a look at the head set. Head sets come in two types these days. Threaded and threadless. Today we’ll look at the threaded type. (If you haven’t already reviewed the tools posts, you can do so here and here.)

A typical threaded head set.

Threaded head sets are identified by the type of stem that you have and by the appearance of the lock nut and adjuster nut on the top of the head tube. The stem for a threaded head set inserts into the steer tube and typically has a 6mm Allen bolt peering out at you from the top. (Although sometimes it is covered up by a plastic or rubber cap, or is actually a hex head bolt.)

If you have a threaded head set, and have determined that your head set was loose in the Diagnosis phase, then here is how to adjust it.

Generally only a real head set wrench will do the trick here.

You will need a head set wrench, which is a thin wrench that will come in a metric size to fit the adjuster nut of your head set. Typical sizes are 32mm, 36mm, and to a lesser extent, 30mm and 40mm. Check with your bike in tow at a local shop to get the proper size, or measure with a calipers.

Once you have the correct wrench, place the front wheel between your legs and squeeze it with your legs to keep the fork from turning as you wrench on the head set. Place the head set wrench on the adjusting nut, as shown above.

An adjustable wrench will suffice for the locking nut.

A good mechanic will have a head set wrench for the locking nut, but we’ll get by with our adjustable wrench here. Just make sure you have it adjusted for a tight fit on the locking nut. It is easy to round off the edges of the locking nut, so be carefull!

Once you have the wrenches on their respective nuts and lined up the handles for the best leverage, you can loosen the lock nut about an eighth of a turn, then hold it steady. Leaving the wrenches on their respective nuts, now you move the adjusting nut with your thin head set wrench clockwise about a sixteenth of a turn. Hold the wrench steady and tighten the locking nut down. Don’t lean into it! Locking nuts can strip out easily, and if you do strip the threads on yours, you will be making a trip to your local bike shop for another locking nut, if not an entirely new head set.

Recheck the head set by grabbing the handle bar on one side and the fork blade opposite of the side of the handle bar you are holding. Try to rock the fork side to side. Feel any movement? If yes- then you’ll have to go through the adjustment steps again to take out the looseness. Remember, small incremental adjustments may take a few tries to get to a satisfactory adjustment.

If you can not feel any looseness, try flopping the handle bar back and forth. Does the fork spin freely, or does it stop after you let go of the bars immediately? Can you feel any roughness or indexing? If so, you may have your head set too tight. So try adjusting it again, this time loosening the adjuster nut slightly. If you can not get rid of an indexing condition, you may need a new head set. Check with a qualified mechanic to verify this.

Next time we’ll adjust a threadless type head set.