Knowing how to tighten a headset is simple and is something that could save your ride if yours is loose for whatever reason, without a trip to the bike shop. There are only three bolts on most stem/headset combos but you have to know which ones to tighten first and how much.
First – Test Your Headset Tightness
To determine if your headset is too loose or tight, lift your front wheel off the ground and spin the bars back and forth. They should turn with ease and not bind in any one place. If they do your headset is likely too tight or in more rare cases, your headset bearings may need replaced. Second, with your wheel on the ground, lock the front brake and rock the bike forward and back. What you are looking for is to see if the steerer tube rocks forward in relation to the frame. It should not move at all and if it does, your headset is too loose and needs to be tightened.
How to Tighten a Headset – Starting From Scratch
First with how to tighten a headset, loosen all the bolts on the stem that tighten down onto the fork. Secondly, take the top-cap bolt on the top of the steerer tube/fork completely off. The top cap will now come off as well. The way the headset works is that the spacers, or the stem itself (depending on how many spacers you have) press down on the outside of the steerer tube. The top cap does not press on, or even touch, the steerer tube/fork. This means that you have to have enough of the spacers or stem sticking up above the steerer tube. You can see this in the image below. Also, remember that when you tighten down the top cap, that gap is going to shrink and could be enough to cause the top cap to touch the steerer tube. You may need to add another small spacer.
Install the Top Cap
Once you have enough of a gap put the top cap and bolt back on and tighten it down snug but not too tight as if you over tighten it you won’t be able to turn the handle bars as the bearings will be compressed. Also make sure your handle bars are straight with your front wheel otherwise you’re going to have to re-loosen everything to line it back up.
Tightening the Stem Clamp Bolts
Once you have the top cap tight enough, now tighten the two bolts (normally two) on the side of the stem to cinch the stem to the steerer tube. Tighten them down evenly meaning tighten one a little and then do the other. Again, these should be snug but not overly tight as you can strip the bolt or crush the steerer tube particularly if it’s carbon.
There you have it; how to tighten a headset. Your headset should now be properly tightened. You can test it by doing the headset tightness test again to make sure it’s not too loos or too tight.