Mountain Bike Dropper Post Install | GMBN Tech Essentials Ep. 10

Mountain Bike Dropper Post Install | GMBN Tech Essentials Ep. 10


– 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 if that’s the case and don’t
forget to click and subscribe!