Overhaul The Headset Attached To A Threaded Steerer On A Bike

Overhaul The Headset Attached To A Threaded Steerer On A Bike

The old type of headset has an adjustable
top race that sits just above the top of the head tube. It screws up and
down a thread, cutting in steer a tube. It usually has hexagonal
flats or a knurled ring. The nuts above also screws up and down
the steer a tube and is used to look the adjustable race in position. The handlebar stem telescopes inside the
steerer tube so it can be adjusted up and down. On the new type of bike headset, the steerer tube extends above the head
tube where it carries a stack of spaces and is topped by the handlebar stem, which clamps on the outside of the steerer
tube and locks everything together. There are no flats on the top races of
the bike headset as they don’t screw up and down. They are squeezed from
above by the handlebar stem. With the bike on the
ground, loosen the lock nut, put the bike in a stand,
remove the front wheel. Unclamp and remove the handlebar stem. Put a strap under the fork crown
and around the down tube. Loosen the lock nut, remove it along
with any washers, lock, no cabling, etc. Taking note of the order in
which the parts come off. It d unscrew the adjustable race, look out for rubber seals and
note which way up they go. Remove balls or rollers. They may be held in a clip or rolling
free if the ball was a free count how many there are. Some may stick to the top
race, so make sure you don’t lose any. Once you’ve and on the top
you can carefully undo the
strap while supporting the forks and take the bottom race
apart. There may be a rubber seal. Not it’s position. Clean the balls or rollers
and the races with degreaser. Inspect the races for signs
of uneven wear or roughness. Changing the balls for new
ones of exactly the same size. Take an old one to the shop as a sample
will prolong the life of the races, balls in a clip are easier to handle, but if you use lose balls you can fit
more in so each one carries less load. If the race is rough or badly worn,
the whole headset needs to be replaced. Fill one of the bottom races with new
grease then fit the rollers or balls. The grease holds the ball in place while
you start to reassemble the bearing. If you’re replacing loose balls,
use the same number that came out. If you’re replacing balls
in a clip with loose balls, put in as many as will fit in line
along the wear line of the race, then remove one so those that
remain have room to roll. Put the steerer tube
back into the head tube. Take care not to disturb the balls
or roller clip stuck in the grease. If the race had a rubber seal,
put it back in the right place. Strap the fork to the down tube. If you turn the bike over, spin
it back to the right way up. Grease one side of the top race
and fit the balls or rollers. Fitany rubber seal and
reassemble the top race, any washers and screw down
the lock nut finger tight. Put the handlebar stem back in the
steer a tube and lock roughly in place. Remove the strap, fit the front
wheel and reconnect the front brake. Put the bike on the floor to make
final adjustments to the headset before locking it. Check the position of the
handlebars and lock in place. Some headsets have a knurled
ring on the adjustable race. These can be adjusted with a
large pair of slip joint pliers. If it has flats, either a
hexagon or two parallel flats, you will need a headset spanner
of the correct size to turn it stand in front of the bike facing the
handlebars with the front wheel between your legs and your head on
the centre line of the bike. Make sure the tool you’re using
fits the top nut, the lock nut. Hold the wheel still with your legs
and turn the lock nut anti-clockwise. Once the lock nut is released,
the adjustable race can turn. If the bearing is too loose, screw the adjustable race down clockwise
as far as it will go with your fingers or using a tool gently then
turn it back a quarter turn. If the bearing is too tight to
anti anticlockwise, a quarter turn. Check the bearing to see if it’s within
the target of free to turn and not too loose. If it’s too loose or too tight, repeat the previous step,
making finer adjustments. Once you have the adjustable
race in a good position, hold it still with a headset
spanner or big pliers. Screw the lock nut down until it jams
against the adjustable race to lock the two parts together. Make a final check that the
bearing is in the target zone. Measure how much of the handlebar stem
is visible above the locknut on top of the headset. Use a tape measure before and after any
handlebar adjustments or maintenance. That way you can go back if you
don’t like the new position. Follow the line of the head tube to find
the head of the expander bolt. It will have a hexagonal
head or hexagonal socket. Unscrew the bolts a few turns to begin. Stand in front of the bike facing the
front of the handlebars with your head on the centre line of the bike, holding the front wheel between
your legs try and turn the bars. If they won’t turn, tap down on the head of the
expander bolt with the soft hammer. This will release them
unless they are seized. Pull the stem right out of the frame with
a combined turning and lifting action. There are two types of fitting. A round tapered expand nut that pools up
into a stem which has slots that allow it to flare out and grip the
inside of the steer a tube, or a quill stem. It’s called this because the end of the
stem is cut diagonally like the nib of a feather pen, which has a slanted nut that slides up
the diagonal to wedge the stem in the steerer tube. Note the position of the minimum
insertion safety limit mark. An aluminium handlebar stem can lock
itself into a steel frame by a chemical process known as bimetallic
corrosion, or cold setting. To avoid this, remove the
handlebars stem once a year, wipe both surfaces, then apply a coat of anti-seize grease
to the inside of the steer a tube, the threads of the expander
bolt and around the nuts. Reposition the handlebar stem and do up
the expander bolt until the stem stays still but isn’t locked. Check the
stem is in line with the front wheel. It’s easier to do this if the front
wheel is aligned to the frame. Check the bars are at the right height, then hold the front wheel steady with
your legs and lock the stem in place by screwing the expander bolt down to
pull the nut upwards to wedge the stem. The stem needs to be tight enough
not to move in rough conditions, but it’s good if it’s not
jammed completely. If you crash, it’s better for the bars to turn
than to break or into the rider. If you carry a heavy
load over the back wheel, the stem needs to be tighter than
if the bike only carries the rider. Lift the front wheel off
the ground, turn the bars. They should rotate smoothly left to
right with no clicks or sticking points. The most likely problem is the front wheel
tending to rest at the straight ahead point. With the front wheel on the
ground, jam on the front brake. Push the bike forward from the handlebars, the back wheel should lift off
the ground with no hesitation, no play between the handlebars and
fork and the rear section of the bike. You can detect tiny amounts of play by
placing your finger at the point where the top tube meets the forks,
when you make the check.

About the Author: Michael Flood


  1. Its a mistake to remove the wheel before the stem. In most cases the stem will be stucked and you will need to turn the bars while holding the wheel with your legs.

  2. I've spent hundreds on bike tools and I only own two of them, and there are yet more I need to buy, will it ever end?!

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