Have you ever experienced something a little bit off with the front-end handling of your bike? More specifically, is there shuddering/vibrations under front braking?
A good place to investigate first is your headset, an often times forgotten but critical component for tip-top performance on any bike. A headset that’s too loose equates to poor front braking performance and diminished handling. Furthermore, an ill-adjusted headset diminishes the headset’s lifespan in addition to the immediate performance issues.
These days the home mechanic is very much in luck as threadless headset systems are easy to adjust. The adjustment process has multiple applications, too, as this process can be used to remedy an existing issue as well as make sure your headset is perfectly adjusted after routine maintenance such as swapping out a stem or simply shifting some spacers around to raise or lower your current stem.
Step 1: What tools do I need?
Tool-wise, there’s not much to making headset adjustments. The top cap bolt, used to apply compression on the stem and headset, will utilize a hex wrench while the stem bolts, used to cinch the stem against the steerer tube, will also utilize a hex wrench. Depending on the manufacturer, the bolts may range from 3mm to 6mm while some recent stems are also featuring Torx bolts, in which case a Torx-specific wrench is necessary.
It’s important to note that while it’s perfectly fine to loosen the stem bolts with a hex/Torx wrench, when it comes time to tighten the stem bolts it’s imperative that a torque wrench be utilized. Tightening to a specific torque value is paramount for functionality and safety. This is of the utmost importance when carbon fiber is involved, either in the stem or steerer tube, as there’s no place for guesswork or estimation.
Step 2: Assess headset
Excessive vibrations/shuddering in the front end are a tip-off that a headset may be loose. To confirm the diagnosis, while stationary simply apply the front brake and then try to rock the bike frontwards and backwards. If there’s play then you’ve got a loose headset.
Step 3: Loosen stem bolts
With the hex/Torx wrench, loosen the bolts that attach the stem to the steerer tube. You don’t have to back them out too far, just enough to release the tension.
Step 4. Tighten top cap bolt
While the bolts that fasten the stem to the steerer tube and the stem to the handlebars have specific torque values to exactly dial in the amount of tightening required, the top cap bolt simply needs to be snug. It’s typically an iterative process as you tighten the bolt and then check via the process in Step 2 to see if there’s any play remaining. Repeat as necessary until the play is gone.
Keep in mind that it’s possible to tighten the headset too much. You’re seeking just enough tension to eliminate any play.
Step 5. Tighten stem bolts
Make sure your handlebar/stem are centered and then tighten the stem bolts to the correct torque setting.
Congratulations on picking up another maintenance skill! Now get out there and enjoy a ride with your newly adjusted headset.