Check and adjust a loose headset

The headset is the bearing set that lets the fork and handlebar turn. When it works loose you feel a knock through the bars when you brake, and the bike can feel vague in turns. Most e-bikes use a threadless headset, which you adjust with hex keys. This guide follows Park Tool's threadless headset guide.

What you need

• Hex keys
• A torque wrench for the stem bolts
• Your bike's manual or the stem maker's torque spec

No headset wrench is needed for a threadless headset. Park Tool says if you can see wrench flats above the top cup, you have a threaded headset and this method doesn't apply (Park Tool).

Check for play first

1. Squeeze the front brake, rest your other hand over the top of the headset where the fork meets the frame, and rock the bike forward and back (Park Tool).
2. A clunk or movement you can feel under your hand points to a loose headset. Park Tool notes that play in the brake caliper or a suspension fork can feel similar, so rule those out (Park Tool).
3. Lift the front wheel and turn the bars slowly. They should turn smoothly with no notch or tight spot.

Steps

1. Turn the bike off and remove the battery.
2. Remove the top cap bolt and cap. Park Tool says the steerer should sit about 3 mm below the top of the stem. If it's flush, a spacer is needed above the stem (Park Tool).
3. Lightly grease the top cap bolt and put the cap and bolt back by hand only (Park Tool).
4. Loosen the stem bolts that clamp the steerer. Park Tool says not to grease inside the stem or on the steerer (Park Tool).
5. Wiggle the stem to make sure it moves freely. If it's seized, stop. The headset can't be adjusted this way (Park Tool).
6. Line the stem up with the front wheel, then snug the top cap bolt until you just feel resistance. Stop there (Park Tool).
7. Tighten the stem bolts and check for play again.
8. If there's still play, loosen the stem bolts, turn the top cap bolt an eighth of a turn clockwise, and retighten the stem bolts. Repeat until the play is gone. Park Tool says always loosen the stem bolts before you turn the top bolt (Park Tool).
9. The goal is the loosest setting with no play. Park Tool says a headset that's too tight feels stiff or notchy and wears early (Park Tool).
10. Check the stem is straight, then torque the stem bolts to spec. Rad lists 15 Nm for the RadWagon 5 stem clamp bolts (Rad RadWagon 5 manual). Park Tool's chart shows stem bolt values from about 5 Nm to 10 Nm for other stem makers (Park Tool), so use the number for your stem.
11. Stand in front of the bike with the wheel between your knees and try to twist the bars. They should not move.

Common mistakes

• Turning the top cap bolt with the stem bolts still tight. It does nothing and can damage parts.
• Using the top cap to clamp the bars. The top cap only sets bearing preload. The stem bolts hold the bars.
• Overtightening until the steering feels sticky.
• Forgetting to recheck cable slack. Turn the bars fully both ways and make sure no brake, throttle or display cable pulls tight.

Videos

When to get a pro

• Park Tool says if you can't find a setting that is neither loose nor tight, the headset may be worn or put together wrong, and dented races call for replacement (Park Tool).
• Play that won't go away even when the top cap is tight. Park Tool says the steerer may be too long and need a spacer (Park Tool).
• Folding stems, quill stems and threaded headsets.
• Any crack or damage on the stem, steerer or fork.
• More: when to call a pro.

Sources

• How to Adjust a Threadless Headset, Park Tool
• Torque Specifications and Concepts, Park Tool
• RadWagon 5 owner's manual, Rad Power Bikes

Stuck after these checks? Find a shop near you.