Adjusting Headset Tension
Headset tension acts as a steering stabilizer when adjusted properly. If the headset is too loose, it can promote wandering and headshake. This is a critical adjustment and it should be checked regularly.
Start by putting the bike on a stand on level ground.
Put weight on the back of the bike so that the front tire does not tough the ground. Position the bars so that the tire is pointed straight forward.
The steering should keep its position. You should be able to lightly tap the bars to the left or right without the front end falling to the steering stops.
If the steering is too tight, the resistance to turn will be apparent while riding.
To adjust the headset, first loosen the top steering stem nut. Then loosen the top fork pinch bolts. Turn the spanner nut on the stem to get the preferred tension.
The tension will increase slightly when the top nut is retightened.
Once the spanner nut has been set, apply red thread lock and retighten the top stem nut to the recommended spec. Then torque the top fork pinch bolts to 18ft/lbs.
Follow up by checking the headset tension on the stand. Once again, the steering should have enough tension so that it has to be continually tapped through its travel without falling to the stops under its own weight but loose enough that it does not hinder your turning ability.