10 Common Mistakes Made When Replacing A Mountain Bike Fork | How To Fit A New Fork

10 Common Mistakes Made When Replacing A Mountain Bike Fork | How To Fit A New Fork


– As you can probably see next to me is Neil’s cross country
bike at the moment. Missing a fork, that’s because we’re about to fit a nice shiny new fork to it. In doing so, I want to point out a fact that there are a lot of classic mistakes that people make when fitting forks. You definitely do not
want to make any of those because they’re really expensive. So here are 10 mistakes that people make when fitting a pair of
suspension forks to a bike and more importantly, what
you can do to avoid them. (deep bass sound) Number one is cutting the
steerer tube to the wrong length. So if you look at Neil’s old fork here, you can see the length of the steerer tube and you offer up the new one, you can see it’s significantly longer. That’s because I do need to trim that down to the correct length. Now I don’t need to tell anyone this, you need to measure
this twice and cut once. You never want to mess this up, it’s a very expensive mistake. Now I could quite easily just measure this against the existing steerer, but really to safeguard yourself, what you want to be doing is
offering up inside the bike, fit the stem, fit the
spaces, make a marking, to where you want to make that cut, and then check it, and then make the cut. Definitely don’t chance
it by just offering it up against what you already have. It’s very easy to make a mistake. (industrial music) – Not leaving enough space
for your stem spacers. Now this is another classic mistake, that you’ll cut the steerer tube down, it’ll fit on the bike, nice and flush, but you have zero adjustment. Also, something a little safety point, is that there should be a 3 millimeter gap between the top of the
steerer tube and the inside of the top of the stem,
and the reason for that is when you’re compressing it
all to preload those bearings, it obviously needs to move fractionally, so it does have to have a little bit of margin of error there. Some stem manufacturers
and some fork manufacturers are now actually suggesting
that you leave enough space and you run a spacer on
the top and you have that margin of error on the
spacer itself so thereby the stem gets a full
interface on the steerer tube. Worth taking into account and
what I always recommend doing is leave that little bit
extra because you can fine-tune your ride. Now Neil actually has had two spacers on his bike previously. I’m going to actually cut it down so it only has the single spacer and he wants it on the top so he can get that nice connection. The stem’s got quite a low stack height which means if you have
that 3 millimeter gap underneath the top of the stem, you’re not having a whole of stem grip from the steerer tube,
so for safety element having that on the top
gives you that little bit of margin of error and you
can tweak around your ride height slightly as well. (transitional keyboard music) – Not having a nice sharp
blade on your hacksaw, this is really important
to get a good, clean cut. A lot of people I’ve seen
using old hacksaw blades just literally hacking
at steerer tubes on forks and not cutting down properly, that’s not what you want to be doing. And also you need to take
into account how you actually use the hacksaw. You don’t
want to be pulling out, you don’t want to be pushing and pulling. Basically, you want to be doing the cutting in one direction, unweighting it, and pulling it back. So nice smooth action to
get a nice smooth cut. There is also another
option available to you if you’re not going to use a hacksaw, and that is a pipe cutter. Now pipe cutters are good to use if you use a high quality ones designed for using on hard anodized
steerer tubes, like this one. What you don’t want to be using is a generic household one
that are actually used for softer pipes, like
copper piping for example, in central heating. If you wind one of those up, you start cutting your steerer
tube with one of those, you can actually flare the
ends of the tube very slightly, enough that it’s going to
make put in the steerer tube through your headset a real pain and also getting your steerer
tube spacers over there and your stem on the end
can be a real tight fit. So, if you’re going to use a pipe cutter, only use a high quality one that’s designed for
using on harder metals. (upbeat industrial music) – Next up is not cutting
your steerer tube level, or having a cut that’s
kind of on the piss a bit. You do not want to do this,
this is not good practice, it looks horrible. And in an ideal world, you want to be using something like this, which is basically a saw guide, specifically designed
for doing this one job. You place this part in the vice,
the fork goes through here, you clamp it in place, and you’ve got a nice accurate guide there to cut your fork steerer
tube in the correct place. However that is quite a specialist tool and if you’re not going to be doing this more than a couple of times, it can be hard to justify the cost, so I have a cool little
hack that you can use to get a similar effect. Here’s, get yourself an old stem, someone, one of your friends
is likely to have one, put a stem on the steerer tube, you can use this as a guide,
basically cut up against the stem. Obviously don’t use the one
you intend on using again because you can scratch and scuff them, and in general you
treat them pretty badly, but this old thing is
ideal for doing just that. (upbeat industrial music) – However you decide to
cut your steerer tube, once you have, you’re
going to need to file the ends of that cut, and
the reason for that is it’s going to leave a
sharp burr around the edge. So A you can cut your hands on that and B it makes it really hard for installing the fork
correctly into a headset. And through headset
space sets the stem and all of that sort of stuff. Now firstly, you want to
have a nice sharp metal file, so you want to do a nice smooth action and give it a slightly rounded edge, and don’t forget to do the
outside and the inside. Take care when you’re checking it in case there are any burrs, because it’s very easy
to just put fine slicing into your finger, and make sure it’s nice
and smooth all over. Now the real important thing here, and the thing that people
classically do wrong, is let those metal filings
go all over the fork, in particular anywhere
near the fork seals. Now they can be a real pain to get off because of the amount of oil
and residue around these, and sometimes you won’t even notice that you’ve got metal
filings around your seals until it’s too late. Think how a fork works,
it’s a telescopic action, and it’s naturally going
to ingest mud, muck, and you guessed it metal
filings if they’re in there. Metal filings will do much damage to the inside of your forks, in particular to those expensive bushings that help them slide up and down, and basically they’re just
not very good for your bike. So, pay attention when you’re filing, don’t let the metal filings
get anywhere near stuff. If you’re paranoid about
it, you could input plastic bag over your fork
when you’re making that cut, just to make sure
there’s no contamination. (upbeat industrial music) – Next up is not installing
your star fangled nut correctly. This is a classic, it
happens all the time, I could even name some
people in this building, that work on GMBN that do
this wrong quite constantly. I’m not looking at you
Blake but maybe I am. So the star nut, there’s
a few different ways you can do this wrong. The first one, is by
not having the correct installation tool and of
course an installation tool for putting these in a
bike is an expensive and a very specific tool for the job. It is the best tool and really is the only
way to do it properly, but you can do it in other ways. One example is literally using the bolt that you use with the star nut and hammering it into the bike. Be careful if you do this.
It’s really easy firstly, to get it wrong and put it in at an angle, once it starts going at an angle, it’s very hard to get right, and you’re never going
to get a decent preload on your headset if you do it like this. The next one is hammering it in too deep. You’re never going to be
able to reach the thing and the only way of getting a star nut out is by continuing to push
it all the way out the steerer tube and then
at the end of the day it’s going to be broken and
not good for anything then. So, that’s two classics, straightaway. Another one is when
you’re hammering it in, they can actually separate. So star nuts are made of three pieces, the two star fangled plates and obviously the threaded section
that holds it together. You can actually shock these
apart inside the steerer tube and you’re never going to
be able to get any preload. You’re just going to
be stuck with something rattling around on the inside. So try and avoid that at all cost. (upbeat industrial music) – Not using grease. We’ve said
this many times with bikes, there’s lots of moving parts
and components that do need lubrication, the chances are
that you’ve probably never put any grease in your headset. Why would you? It’s kind
of a fit and forget thing because the fact is
hidden away on the bike, it’s not like something
mechanical you can see, like your transmission. So, when you have a fork out of the bike, it’s a really good idea
to take the bearings out, inspect them, make sure
they still feel okay, give them a wipe down, make
sure they’re fairly clean, the same with the cups on
the inside of the frame, and put a load of fresh grease in there. The amount of people I know
that don’t have any grease on their bikes and insist
on still riding them, you’re just going to kill
those bearings really quickly. Use loads of grease and it
makes everything better. (funky industrial music) – And the last one on the list is not lining up your handlebars
and stem correctly. We’ve all done it and we’ve
all sat on a friends bike and realized that the
handlebars are kind of off skew. It’s quite hard to get
them very accurately set up but there’s a few little
tips and tricks you can do to make it a little bit
easier, because it can be, you know using your eye to
get it right, quite difficult. Now the first one is most
people try to line up the stem with the front tire,
this used to be quite easy when you had nice long stems,
horrible long stems in fact, but these days we have really short stems, it’s very hard to actually get that right. So a much better tip is actually
to line up your handlebars with your fork clamps because
you can look directly down at the handlebar relationship,
it is much closer to them. But one last tip you can do, this is taking things to extremes though, would be to remove the
controls off your bar, so take off the grips or
perhaps you can just move your brake levers out of the way, lean the fork legs up against the wall, and handlebars up against the wall, and you can actually use that flat wall, assuming the wall is completely flat, to make sure your bars and
your forks are in line. Clamp it all down and then
when you put your wheel back in you’ll find it is dead, arrow straight. Don’t be one of those people
who rides with a wonky stem. (industrial music) – Messing up your cable routing. Now there’s plenty of things
that can go wrong here. Obviously, you want a nice
clean route for the front brake to get down to the fork. Now firstly, what you
want to make sure you do, is not having the cable running up, or the hose running up the
outside of the fork leg. First reason for that is
it’s quite likely to rub on your fork and rub that paint away. The second reason for
that is it’s very easy to be snagged, to roll
to feel the undergrowth, and if you have a crash you
can actually damage that front brake hose very easily. You want to be routing from the inside of the fork here, on
the inside of the leg, and up through the archway here, with the supplied cable mount. Now this is the culprit of
loads of classic mistakes. People mess these bolts
up and strip these threads all the time, it’s a very delicate bolt, it’s only retaining just to
hold that cable in place. You’re not really clamping it
down with any sort of force. So make sure you don’t
go crazy on the anarchy. Don’t be hanging that off
and actually damaging it. (jazz transitional music) – Not using a shock pump
to set up the correct air pressure in your fork. I
know what the temptation is, I know some people who
do this quite often, using a track pump to inflate
your fork is not a good idea. So forks run at fairly low
pressure, talking up to 100 PSI, it’s not much and it’s
something very achievable by a track pump, but you
definitely do not want to be using a track pump with any sort
of adapter on your fork. The reason for that is
it forces a lot of air in very, very fast. It’s very
easy to damage your seals. Very easy to damage the
valve on the top of the fork. Only ever use a proper shock pump. That is what it’s designed
for, for shocks and forks, and they’re nice and accurate, and you’re not going to damage your expensive suspension fork. Well there we go there’s
ten classic mistakes people make when they’re
installing suspension forks to their bikes. Don’t
be someone who makes one of those ten mistakes. Do it properly. Do it right. And you can
enjoy having a suspension fork on your bike. For another mistakes video, click down here for traveling
mistakes for your bike. All sorts of stuff that
you do like leaving your front wheel at home and knocking
those brake pads together when you accidentally use the
lever in the back of the car when you’ve not got a
front wheel in there. And click down here if you want to learn how to set up your
suspension in ten minutes. Really easy how to video,
anyone can do this, and you can do it anywhere. As always, give us a thumbs up if you like the video, let us know what you think
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