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.