How To Cut A Road Bike Steerer Tube

How To Cut A Road Bike Steerer Tube


In order to adjust the height of your
handlebars, you either move space from above or below your stem, depending
on whether you either want to raise it up or move it down. And that is the reason
why bikes are sold with loads of spaces and really long steerer tubes.
So, that means that you can adjust the bike to fit you without having to buy any
new bits. But that does mean that when you end up setting your position,
particularly if you like a really low front end, that you may end up with a
rather unsightly protrusion. And no one likes an unsightly protrusion. So, the
solution is to cut your steerer tube. This decision is not to be taken lightly,
because once done it cannot be undone. But when you’re completely set on your
position, it’s the logical thing to do. Firstly, we need to measure where
we to actually cut our steerer tube. So, we need to remove the top cap and then
any spaces on top of the stem, and then mark the line on the top of the
stem onto the steerer tube. Then we simply pop the stem off and drop
the forks out . You can either mark the steerer tube with a pen or just
a really light scratch with the end of a flat-bladed screwdriver. ♪ [music] ♪ With our forks out, we’ve now got a
decision to make. If you want your stem and steerer tube to be completely flush,
then you need to take that line that we’ve just marked and then make a
second line 3 millimeters below it. Now, that will give the top cap
enough room to actually do its job, so it needs that little bit of space
to compress all the bearings back down. However, many of you, and I will include
myself in this as well, subscribe to the “always have one 5 millimeter
space on top of your stem” rule. Now, the reason being that having a little
bit of steerer tube extending above your stem, means that when you come to clamp
it, and particularly important carbon steerers. it’s clamped extra securely.
Because there is a risk that if the stem extends over the top, it can start to
squeeze the carbon steerer tube down, potentially deform it, and
delaminate it. Now, admittedly, take one look around the Pro Peloton,
you’ll see that no team mechanic subscribes to this school of
thought for their thoroughbred riders. But, for the rest of us, firstly longevity
is really important, any added security we can get is also important. But then
perhaps the most important thing, is that most fork manufacturers, and indeed
bike manufacturers, will recommend that you have a 5 mil space on top. So, today
we are going to not subtract 3 millimeters, but add 2 millimeters to our
line. Another important point now, and I’m afraid we’re still not anywhere near
cutting yet, we are at the preparation phase, but it is important nevertheless.
If you have an alloy steerer tube, so not like this one which is carbon, then
the chances are that in the top of it, you will have one of these, which is a
star fangled nut. Now, it would have been whacked down inside your steerer tube
and its job is for you to be able to screw your top cap into it. And then the
star fangled nut won’t pull out and you can preload the headset. Now, what it means in this instance is the
chances are your star fangled nut is probably going to be sitting somewhere
exactly where you are cutting. So, we need to move the star fangled
nut further into the steerer tube. The way we do that is to actually hit it
with a hammer. Now, there’s a budge technique, I will tell you it first. You
need to screw your top cap bolt into the star fangled nut and then hit it very
gently with a hammer to get it to move. But, like all budges, there is a risk that
it could go wrong, and that is that you could knock it so that is angled
incorrectly, and then you won’t be able to preload your headset. So, with that in mind, much better to get
hold of one of these, which is a star fangled nut driver, and it means
that it will go in perfectly straight. However, hopefully, you are lucky
enough to have a carbon steerer, in which case you are not going to have a
star fangled nut. You are going to have something that looks a bit like this,
which is a compression sleeve, and then it’s very easy. All we’ve got to do
is loosen that 6 millimeter Allen bolt and then the whole assembly just pulls
out the top of your steerer tube. Now, I’m conscious that we still haven’t
actually cut anything yet, and that is ultimately why we’re here. But bear with
me, preparation is everything with this. We now need to mark over our
cut line with a piece of masking tape. just a single layer. Now, there is a
risk that you won’t actually see your cut line anymore if you got a little masking
tape over. So, I’m using a small piece of masking tape to actually mark the cut
line and then I’m going to tape over it. Now, what this does is it ensures that you
get a much better cut. So, it stops any risk of the carbon fraying, and then it
also does a much nicer job so that we can see now that’s our cut line and
that is our layer masking tape. Then we need to select the right
tool to actually do the cutting with. So, a hacksaw is perfect for the job. If
you’re cutting aluminum steerer tube, then you want a blade
with about 24 teeth per inch. If, however, you’re working with carbon,
you should really have a carbon specific blade. So, that’s got much finer teeth,
either 32 teeth per inch or this, which actually doesn’t really have any teeth at
all. I don’t know how to describe that. Looks pretty cool, don’t you think?
Basically, it’s just much better at working with a softer, the more
delicate material. Look at that. What a tool. Right, we’re actually ready to cut
something now. Firstly, we’re going to show you the rather crude and not
really too recommended method, which is where we’re actually going to do
it freehand. We are however going to use some form of cutting guide, and that is an
old stem. And make sure is an old one, because you’re going to damage the finish
on it. But you simply put the stem up to your cutting line, and then use that to
cut against. That way you get a straight finish. Now, clearly that is not an old
stem. That is my actual stem, so we’ll put that safely to one side. Clearly, though,
for an important job like this, you do need the right tools for the job. And that
tool is a cutting guide like this one from Park. Now, one end clamps in a vice and
then you thread your forks into it, and then line up your cut mark with the
actual cutting guide. There we go. Right. You’ll have noticed I’ve stuck a
pair of gloves on. That’s just because we don’t really want to get anywhere
near carbon dust. It’s not very nice. And for that reason, you should also wear
a mask as well. Then we’re just going to start sawing. ♪ [music] ♪ Well, that’s our cut done. Looking good,
but we’re just going to take a fine file to it and put a slight edge at 45 degrees
on it. Just to finish off any slightly rough edges. ♪ [music] ♪ Right. I’m happy with that. Now, you may
want it completely flat and that is fine, but do check with the manufacturers of
your fork, and indeed your frame, to make sure that is okay with them. Well, there
we go. Not actually all that much cutting involved for this video but an awful lot
of preparation, and it is totally key. So, bear that in mind and remember you
can’t measure it enough. Because once you’ve cut it, you cannot uncut. Well, there are loads of maintenance
videos here on GCN. And to be in the right place for them every week, first of all
you might as well subscribe to the channel. It’s completely free to do it,
just click on the globe. And then if you want some more videos, well first of
all, how about a video about servicing and setting up your headset. Pretty relevant and you need to
do it. So, click just up there to get through to that one. Or for a video about
positioning and indeed how high or how far away your handlebars should be from your
saddle, then click just down there for that one.