- This is the GMBN tech essentials series,
which is our easy to follow
guide to understanding
your bike and learning how to work on it
and maintain it yourself at home.
In this particular video we're looking at
how to install a cable
operated dropper post
which is a fantastic upgrade
for any mountain biker
to add to their bike, and
they're very easy to fit.
(dramatic electronic music)
Okay so first up a little
bit about the dropper post
firstly why would you want
a dropper post on a mountain bike?
The simple reason is
it enhances your ride,
so it won't physically change
anything about your bicycle
because you can actually
drop the seat post manually
in the frame, but what it
enables is with a flick of
a button, you can lower that seat,
which means it gets it out the way,
meaning you're gonna feel a
lot more secure, a lot safer,
and you're gonna be able to
lower your center of gravity
which is really important
when you're riding really
fast rough technical, and let's face it,
some dangerous stuff
that can be quite scary.
By lowering that seat out of the way,
it means you can off the back of the back,
it means the saddle is not
going to hit you in the stomach
or anywhere else, and it
just generally enhances
what you get out of your ride.
Now when you're picking the dropper posts
there's a few different
options on the market
so the first thing you need to know is
what sized frame have you got?
Now typically they fall into
30.9 millimeters or 31.6
millimeter diameters.
Now you can find out the size
of your existing seat post
by simply removing the
post from the frame,
and if you look right here on the post
you'll see it has etched into
it the actual sizing for this.
If you're unsure about
this you can also find out
on the manufacturer's website
of your bicycle frame,
they will generally list
the actual frame size
internal sizing here
as one of the features
in the geometry charts and specifications.
The next thing you need to
decide is if you're gonna have
a hydraulic operated post
or a cable operated post.
Now for hydraulics there's
not really many options
on the market, the
RockShox Reverb is the king
when it comes to hydraulic terms.
But the cable operated post
there are several options on the market.
And fundamentally they
work in the same way
although there are two
designs within that.
Some of them have the cable
nipple operated at the post end
and others have them operated at
the actual dropper post lever end.
Now the only difference
really in operation is
it's more of an installation thing,
you just have to fit things
in a slightly different order,
but we'll get into that in a minute.
Now the final thing you
need to take into count is
how much actual drop your post can have.
Now when they first came out,
I think they were about 75 millimeters
was pretty much standard
but now you can have
up to 176 millimeters on some posts.
Now in an idal world you want
the maximum amount of drop
you can possibly have, but
it's not just as simple
as buying one to fit onto
your bike, you need to take
into account the length of your seat tube,
the amount of exposed seat post you have,
and your inside leg measurement.
Now it's fairly easy to work
out how much drop you can get
away with because on manufacturer's sites,
this one is a Crank Brothers seat post,
they will list the height
basically of every part
of that post so you can
figure out how much drop
you can fit into this space.
Now just take the time
to figure it out for
your particular bike, you want
the maximum drop you can get.
On this particular one I
could get a 175 into here
but I have a 150 mil
drop post which should be
more than adequate for this bike,
and that's what I'm gonna install today.
Now before we get started
you're gonna need some kit for the job.
Firstly you're obviously going
to need your nice new shiny
dropper post, next up you're
gonna need suitable cables
for it, that means a new
inner cable, full length,
and outer cable, ferrules and end caps.
You're also gonna need a tape measure,
some allen keys, in this particular case,
a five, a two and a three millimeter.
You're gonna need a pick
or a small screwdriver,
I'll show you why later in the video.
You'll need some sharp cable cutters,
some needle nosed pliers,
a sharpie, you'll also need
some sort of spray lube or lubricant
in order to get inside that outer hosing,
and you're gonna need some sort of
grease or assembly compound
that is compatible with your frame.
I also recommend having some thread lock.
And if you wanna get a bit
more particular about it
a torque wrench would be really helpful
and finally if you have access to one
an internal routing kit
is really really helpful,
though not essential.
Now there's no specific order
in which you need to do this
but I'm gonna start at
the front of the bike
with the dropper post remote lever.
Now you need to consider how easy
your dropper post lever is to use.
The beauty of a dropper post
is you never really have
to break momentum when
you're riding a bike
in order to get the saddle
out the way when there's
a bit of scary or
intimidating trail coming up.
So in order to do that you
need to be able to just
literally just loosen your
grip and move your thumb,
you don't really wanna be moving
your hand around too much.
So play around until you get
a position that suits you.
This is how I like to
hang mine under the bars,
it's very easy to reach whether I'm
sat down on the bike in order to
drop the post in the first place,
or if I need to get the post
up in hurry when I'm out
the saddle I can still reach
it without having to roll
my wrist forwards, just
take that into account
and get a position that works for you.
Now the process for installing
the cable on the inside
of the frame does vary
slightly between frames.
Now if you're lucky enough
to have a new fangled
carbon fiber frame it may
well have internal channels,
which simply means you feed
the hosing into the frame
at the front and it will pop
out in the relevant place.
Now this particular frame
does not have that so
I'm probably in the same
situation as a lot of you.
Now this is why the
Park Tool is so useful.
You simply feed it into the frame,
you follow it along with the
magnet until it pokes out
where you need it to, and then simply
you attach the end of
it to your outer hosing
and you pull it back through.
It's an ingenious system
and it's painfully simple
how it works, now with the hosing in place
inside the frame, now
it's time to cut it to
the correct length, you have
to do this at this stage
you can't do it clearly
when there's an inner cable
inside it because you'll
cut through that as well.
This is a pivotal part of
fitting the dropper post
to your bike, and making
sure it works correctly
so get this right the first time.
Now the first thing you
need to do is ensure you
have an adequate amount
of cable at the front here
in order to meet with the
actual dropper post lever
and not be hindered by
any movement of the bars.
If your bars spin most of the
way round, allow for that.
You don't want it to be
pulling the cable out
in the event of a crash.
If in doubt have a little bit more cable.
It does mean that it might
look a bit more unsightly,
but it definitely means it
will work in all conditions.
And now it's over to the
seat post part of the bike
where your outer housing will be
poking out of the seat tube there.
Now this is where the
sharpie comes in handy,
and in fact it doesn't
matter if you've got sharpie,
a tippex pen whatever it is,
you need to make a mark on the cable
that's completely flush
with the top of the frame
at this point.
Now once you've made that mark,
then you can pull that hose
back through, careful you
don't lose it in the frame
at the head tube end, but
you need to pull it out
because you need to make another mark
in order to cut it in the correct place.
Now with this Crank Brothers seat post,
I need to make the second
mark out of 165 millimeters
and that's where I make my cut,
and that makes the outer
hosing the correct length.
Now the length that you need
to cut yours to does vary
and it will stipulate this in the manuals,
and this is why it can
be a little bit confusing
but hopefully seeing me do this
explains it a lot easier for you.
Once you've trimmed
down the outer housing,
you need to get your fine
pick or a screwdriver
or whatever sort of implement
you have in place of that
and just make sure that the
inside of the outer housing
is not crushed, make sure the
cable can pass through there
nice and freely.
At this point I also like
to spray a bit of spray lube
through there, hold a
rag over the other end
just to catch any that missed.
You do not want this to go
anywhere near your braking surfaces.
Now at this point you need to just be sure
of which style of cable
operated dropper post you have.
Some of them house the cable
nipple at the remote end
and they use that to pull the
cable and basically operate
the system on the end of the dropper post,
but in this case this
is a Crank Brothers post
you actually have the
nipple housed at this end,
and then it's clamped
at the remote end, so
that is important to
know because that affects
the next stage of installation.
Now just before you put
that inner cable in,
make sure you get the cable ferrules
and put them over the
housing on both ends.
Cable ferrules are there
to keep muck and grime out
and keep that lubricant
in, and they're also there
to stop inner parts of
that outer cable migrating
basically moving out from
where they shouldn't be,
so it basically forms a system
so make sure you do use those
because then your outer
hosing will last a lot longer.
Now because this particular
cable operated dropper post
is the crank design, it
means the nipple is housed
at the bottom of the
post so, first step now
before putting the post into the frame
is to feed the cable through
here and the cable nipple
actually sits in this blue piece.
With the nipple in place
you simply push the piece
back into the bottom of the post there
and thread on that retaining ring.
Now there should be plenty
of thread lock on there so
basically screw it up tight by hand,
you won't need to use a tool on that just,
tightening by hand is sufficient.
And then you're basically
ready to get the dropper post
into the frame.
Now at this stage I recommend
using some assembly compound
as opposed to a grease on the
inside of the seat tube here,
and you just need a blob on
your finger and smear it around.
Now assembly compound
is essentially grease
with particles that float in it,
to help increase the friction
and that means that the post
has less chance of moving
sliding, creaking anything like that,
and it puts less strain on that bolt
that you need to hold it in place.
Just make sure that if
you have a carbon frame
that you're using a particular
compound that is carbon safe.
This one is carbon safe but
it also means that I can use
this on alloy frames too.
Now you need to push the seat
post down into the frame,
and if you're smart earlier
on you would have taken note
of your saddle height
at your optimum height
and you can insert this into the frame
at the preferred height
to suit that exactly
because it's obviously fully
extended in this position
so that is simulating
your full saddle height.
Clamp it up nice and
tight, make sure you don't
over clamp it there will
be a torque reading on
your actual seat post clamp there,
I do suggest that you obey
that because of the fact that
it is very easy to strip
the bolts out those
or over tighten them, if
you over tighten them,
you can actually damage the
post and hinder its performance.
With your seat post in place and secured,
you just wanna make sure
that the inner cable is
nice and taut and then feed it through
the remote assembly there.
Now look for that tiny little hole there,
that is where it needs
to go through and there's
a little grub screw, a little
two millimeter grub screw
that holds it in place.
Now at this stage, I wouldn't
bother cutting the cable
just yet, I'm gonna swap to
the back of the bike again
and install the saddle first
because I just wanna make sure
it operates correctly before
trimming that inner cable down.
So you'll need a five
millimeter allen key to
loosen the clamp bolts on there.
Now you'll find just by
factory specs those clamp bolts
will have some thread lock
on there, but it wouldn't do
any harm to put an additional
blob of fresh thread lock
on there, and get your saddle
into your preferred position.
And finally now is the moment of truth,
time to just check it's working.
So take your bike out the
stand if it's in a stand
to start with, and just the operation,
so operate that lever, put
your weight on the saddle
and hopefully it will operate sufficiently
and it will come back up as planned.
And if you are running into problems,
it's generally down to having too much
or too little tension on there,
so have a little tweak
with the barrel adjuster
on the remote lever and hopefully
it should be absolutely perfect for you.
Now at this stage if you
haven't needed to pull
any more cable through,
you've got the green light
to trim that cable down.
Now trim it quite close
to the actual remote so
you can tuck it out the
way, and then of course
make sure you put a cable
end cap over the end
just to stop it fraying.
So there we go that is
the basics of setting up
and installing a dropper
seat post to your bike.
Hopefully that's useful for you guys.
For a couple more useful
videos click up here
on setting up your cockpit
so that might help you
with the positioning of the
lever if you're a bit unsure
of that in relation to your brake levers
and the effects it has,
and click down here if
you wanna click through
to our essentials playlist
it has all the rest of
the videos in this series.
Now I hope you guys liked this video
and I hope it is useful for
you so give us a thumbs up
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