Road bike maintenance - steering
Time: 20 minutes
Difficulty: Traditional headset adjustment - slightly tricky; other stuff - easy
- Traditional headset: headset spanner, large adjustable spanner
- Threadless headset: 5mm or 6mm Allen key, handlebar stem adjustment, 5mm or 6mm allen key
Two types of headsets
are commonly fitted to road bikes. Traditional headsets
have a set of bearings at the top and bottom of the head tube. They are secured by a lock nut on top of the forks and the handlebar stem slots into the fork column.
To check if your headset is too tight lift the front wheel off the ground and turn the handlebars left and right. Does the steering feel stiff or 'notchy'?
is becoming increasingly common. Introduced in the mid-1990s, initially for mountain bikes, it has filtered onto road bikes as it can save a small amount of weight and it is easier to adjust than the traditional set up. Aheadsets require a longer, unthreaded fork. The handlebar stem clamps around the fork column and tightens down to adjust the bearings in the headset. A single allen bolt in the top cap adjusts the bearings and the bearing adjustment is simply locked into place by the bolts fastening the stem to the steerer.
Traditional headset stem adjustment:
Undo the expander bolt about 5mm (this is the bolt at the top of the vertical part of the stem).
Give it a sharp knock downwards with a soft mallet to free it. The stem height can then be adjusted.
Re-tighten the bolt. Hold the front wheel between your knees and twist the bars from side to side - you don't need to use undue force - just to make sure the stem is secure. Traditional handlebar stems can easily become seized in place by rust or fusion between the stem and the fork column. It is well worth removing your handlebar stem and lightly coating it with an anti-seize grease every 6-12 months.
Threadless stem (Aheadset) adjustment:
Handlebar height is adjusted by moving spacers from under or above the stem. If sufficient adjustment is not possible this way you will need to buy a new stem of a different angle or 'rise'. To move the spacers, remove the allen bolt in the middle of the stem and the top cap completely. Loosen the allen bolts at the rear of the stem. Remove any spacers above the stem.
Pull firmly upwards on the bars and stem. These should slide off the fork column fairly easily. Remove the spacers below the stem if you want the bars lower. Add spacers below the stem if you want to raise the bars. Replace any spare spacers on top of the stem - do not leave any out or you won't be able to adjust the headset bearings. Refit the adjusting cap. The headset will now need adjusting - see the next section.
With either style of stem and headset, loosen the clamp bolt at the front of the stem (some stems have two bolts - loosen them both) and rotate the bars to the desired angle. Then grease and carefully re-tighten the bolt(s).
To check if your headset is too tight lift the front wheel off the ground and turn the handlebars left and right. Does the steering feel stiff or 'notchy'? If so, the headset is too tight, or it may need replacing. Check also that there isn't any 'play' in the bearings. Apply the front brake and gently rock the bike backwards and forwards. Feel with your finger at the lower headset race for movement.
To adjust a traditional headset:
Undo the top headset locknut with a large adjustable spanner or special headest spanner (these are usually slim spanners with wide 32 or 36mm jaws). Adjust the 'race' below it until so that there is no play in the bearings but ensuring the forks are free to turn. Hold this race with a headset spanner while you tighten the locknut above it. Recheck your adjustment. It may take a couple of attempts to get the correct adjustment. If your headset is very worn, it may not be possible to get adjustment perfect, in which case take your bike to a dealer to fit a new headset (this requires special tools).
On a threadless headset:
Slacken the allen bolts securing the stem to the forks one turn. Tighten the allen bolt in the adjusting cap until no play can be felt in the headset. Line up the stem with the front wheel and tighten the stem fixing allen bolts. Check that forks still turn smoothly.