in this video we will show you how to
remove and install a Threadless stem on
a bicycle hi trimmer here with Park Tool
Company let's start by talking about
what a Threadless stem is when we say
Threadless stem we are referring to a
system where a fork with a non threaded
steer tube extends through the head tube
a stem then clamps around the outside of
the steer tube along with spacers if
necessary
finally a top cap keeps everything in
place and acts as a headset adjustment
many older bikes and some lower end
bikes have threaded steer tubes the
stems used with these systems are
referred to as quill stems which are
inserted into the steer tube and fasten
with an expanding wedge there's a
separate video on their removal and
installation found at the top of the
screen Threadless stems will typically
have one two three pinch bolts used in
conjunction with a compression slot to
hold the stem to the steer tube they
will also have two two six bolts
securing the faceplate and in some cases
they hook on with one side and bolt on
with the other stems come in different
steer tube and handlebar sizes it is
wise to measure your components to
ensure that you are installing or
ordering the correct stem here are some
common handlebar diameters there are
some outliers on some older bikes here
are some common steer tube diameters
incompatible components can be a safety
hazard so always double check with the
manufacturer for specifications and
compatibility information there are also
shims available to convert a smaller
diameter bar or steer tube to a larger
size
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stems also come in different lengths
measure from the center of the steer
tube to the bar center and angles
typically between 0 and 20 degrees these
measurements are generally marked
somewhere on the stem or its packaging
stems can be installed in an up or down
position to adjust the bar height
without changing space or orientation
this is often referred to as positive
and negative rods when making drastic
changes to the angle or length of the
stem changes to housing lengths may be
required stems are usually accompanying
on the steer tube by spacers these
spacers come in a multitude of different
thicknesses colors and materials they
allow for height adjustment and they
also play a role in the headset
adjustment when installing a new stem it
is important to pay attention to the
height of the stem and the amount of
spacers that you were running before if
you'd like to match the height of your
original stem measure from the top of
the tire to the center of the handlebars
and write it down we'll come back to
this number later typical tools for this
procedure include appropriately sized
wrenches a torque wrench or torque
driver with appropriate bits grease or
threadlocker for the bolts assembly
compounds such as Park Tool s AC 2 4
carbon fiber handlebars and toe straps
zip ties or something similar to secure
the bars and fork while the stem is
removed this procedure can be done with
the bike in a repair stand with the
front wheel removed or on the ground it
can be helpful to straddle the bike for
stability
start by removing your old stem remove
the face plate bolts while holding the
faceplate in place once you have the
face plate off the bars will be hanging
free it is good practice to use a toe
strap or something similar to suspend
the bars and keep the cable and housing
from kinking loosen the pinch bolts at
the steer tube one full turn is more
than likely enough next we will remove
the top cap before we do note that it is
currently the only thing keeping the
fork from falling out of the bike if you
are working on the bike in a repair
stand use another toe strap or zip tie
to keep the fork in place now loosen the
top cap bolt and remove the top cap
you should then be able to pull the stem
free of the steer tube
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set the bike on the ground and ensure
that all components are fully seated
with no gaps configure the stem and
spacers to the desired stem height
measure if so desired if the new stem
has a different stack height than the
old one you will need to rearrange the
spacers accordingly the stem or spacers
should be slightly above the top of the
steer tube approximately three
millimeters if they are flush or below
the steer tube headset adjustment will
be impossible acquire additional or
different size spacers to reach the
appropriate height it is also possible
that the new stem is taller which may
require you to remove a spacer when
dealing with a carbon fork it is
critical to have the steer tube go all
the way through the stem in order to
reduce stress on the end of the steer
tube it is then necessary to have a
spacer on top of the stem apply grease
to the top cap bolt and install the top
cap the top cap is in charge of setting
the headset adjustment Snug this bolt up
for now we will fine-tune this
adjustment near the end of this process
if you are installing a carbon bar it is
wise to apply an assembly compound such
as park tool s AC to where the bar mates
of the stem this will help create the
needed friction between the bar and the
stem to resist rotation it will also act
as a barrier between the bar and stem
materials apply grease or threadlocker
not both to the face plate bolts place
the face plate over the front of the
bars and thread in the bolts but do not
tighten them fully these bolts should be
tightened evenly and the gap between the
stem and the face plate should typically
be even on the top and the bottom there
are a few stems out there that require
one side be fully tightened before the
other side inquire with the manufacturer
for more info
before fully tightening the bolts stand
over the bike and set the bar role to
your preference you will also want to
make sure that they are centered at this
point typically bars will have markings
to assist with centering and roll now
fully tighten and torque the face plate
bolts in an X pattern a typical Torx
pack is four to six Newton meters or use
perceived effort which means applying
about 11 pounds of effort to a wrench
held four inches from the bowl now snug
the top cap down until there is slight
resistance the bars should turn freely
with very little resistance in this
example the top cap is too tight loosen
the top cap one eighth of a turn and
test again next straighten the
handlebars it can be helpful to use a
ruler against the fork legs as a
reference point
snug the pinch bolts test the headset
adjustment by holding the front brake
firmly and rocking the bike back and
forth put your fingers on the top
bearing cover and the top cup of the
headset and feel for play which can be
felt as a slight knock it may also help
to turn the handlebars 90 degrees this
isolates work play if you feel play
loosen the pinch bolts tighten the top
cap another eighth turn retighten the
pinch bolts and check again continue
until the play is gone
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finally torque the pinch bolts a typical
torque spec is four to six Newton meters
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thanks for watching you can find
hundreds more videos like this one on
our channel here on YouTube and we're
constantly working on more so be sure to
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Park Tool and check out our website
which has even more content to help you
make your bike better
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