To cut or not to cut – that is often the question when we talk about the bicycle steerer tube.
This humble but vital part found at the front of the bike, connecting the fork and the stem and handlebars, can cause some head-scratching.
“How long should my steerer tube be?” “Should I cut down my steerer tube?” “What is a steerer tube extender?”
Fear not! We have you covered. We’re going to be getting into everything you need to know about steerer tubes, covering:
- What Is A Bike Steerer Tube?
- Should I Cut Down My Steerer Tube?
- Cutting Down A Bike Steerer Tube
- What If My Steerer Tube Is Too Short? 3 Options
Let’s get into all things steerer tube!
What Is A Bike Steerer Tube?
A bike steerer tube connects the stem and handlebars to the fork – and by extension the front wheel. When the handlebars are turned, the steerer tube moves to steer the front wheel.
The bicycle steerer tube is a part of the fork, rather than an independent part in its own right.
Bike steerer tubes are most commonly made from aluminum, but are often carbon fiber for high-end bikes.
They are normally mechanically expanded or glued into the fork’s crown, which connects to the blades to make up a fork.
The steerer tube then extends from the fork, through the bike frame’s headset, to connect to the stem, which clamps around it.
As the point of connection between the handlebars and front fork, force is transferred through the steerer tube to allow the cyclist to steer.
Steerer tubes are often manufactured longer than necessary, with the expectation they’ll be cut down to length.
Should I Cut Down My Steerer Tube?
On a bike, the rider is able to set their desired handlebar height by mounting the stem at the appropriate point on the steerer tube.
If your steerer tube is already the right length, it was likely built to size by the manufacturer, (or perhaps already cut down by a previous owner if bought secondhand).
Often when riders cut down their steerer tubes, it’s to increase performance by providing a more aerodynamic riding position.
Lowering a bike’s handlebars gives you low and aggressive bike geometry, with stiff and responsive steering. So it’s a straightforward way to cycle faster.
Lowering your handlebars leaves some length of extra, unneeded steerer tube that extends above the handlebar stem. This can be dangerous in the event of an accident.
So if you have a lot of extra length, are certain of your setup and unlikely to need to raise the handlebars, and you’re wondering: “Should I cut down my steerer tube?” – the answer is most likely yes.
Cutting your steerer tube can hurt the bike’s resale value, though, and this becomes more severe with a more severe cut.
So, think carefully before you do decide to cut down your steerer tube.
You’ll cycle faster with a lower handlebar stem and a cut steerer tube, but leisure cyclists might not want to bother with a serious bike modification like cutting the steerer tube.
So unless you’re looking for peak performance, it may be advisable to persevere with a slightly higher handlebar position.
However, we don’t recommend cycling with any more than a minimal number of spacers on the steerer tube above the stem. If you find the handlebar height you’re sure you want and the steerer tube is too long, it’s worth cutting it down.
How To Cut Down A Bike Steerer Tube
To properly, and safely, measure cut your steerer tube, you’ll need the following tools:
- A pen
- A hacksaw (or a plumber’s pipe cutter)
- A metal file
#1. Measure Where To Cut Your Steerer Tube
You want to cut your steering tube to perfect handlebar height, so you don’t have a protruding extra length of the steerer tube.
But what is this length? How high should your handlebars be?
You want your handlebars to sit at the right height for proper cycling form.
Correct handlebar height is different for everyone, but as a very rough guide:
- Handlebars should sit roughly level with the middle of the saddle for leisure cycling.
- Handlebars should sit up to 6 cm below the saddle for performance cycling.
Thankfully with spacers, you’ll have room for adjustment after you’ve cut the steerer tube, so there’s some room for fine-tuning as you go – provided you don’t cut too short.
Add enough spacers to the steerer tube to set your stem to your preferred handlebar height. Then, add an additional 15 mm or so of spacers below.
If you’re not confident in your preferred handlebar height and want to leave some wriggle room, add a spacer or two above the stem as well (you’ll remove these later).
If you’re confident in your desired height, just one spacer on top is fine, but if not go for two or three to give you around 3cm of room for adjustment later. The point of this is that you can always cut away more later, but you can’t add length once you’ve cut it off!
With your handlebar stem mounted to the steerer tube with spacers above and below, take the bike for a gentle (and very careful) spin.
Assuming the handlebars feel right, you’re ready to mark and cut off the extra length of the steerer tube. If you’re certain you want them lower, remove spacers and go again.
Remember, the spacers below the stem are the ones dictating your handlebar height, and the spacers above are the ones giving you a margin for error when you cut.
Bear in mind, though, that the more margin for error you’re giving yourself, the further above your ideal handlebar height you’ll be once you’re finished, given you’ll have to add more spacers below to avoid having much of the steerer tube protruding above the stem.
For the first cut, we strongly recommend leaving at least one spacer above the stem – you can always remove it and cut it down again later, once you’ve had a chance to test it.
Once you’re satisfied, mark the level of the top of the uppermost spacer on the steerer tube.
Now, remove the spacers and stem until you’re left with just the steerer tube, and mark a second line 3 mm below your first mark, ensuring it’s level.
This is the level at which you should cut your steerer tube. The 3 mm space you’ve created is to accommodate for the headset’s bearings.
And remember: measure twice, and cut once! Absolutely avoid cutting your steerer tube too short. Measure precisely, so you get it right the first time.
Extending a steerer tube is technically possible, but not as reliable or safe. Most cyclists – including us – would warn you against it. A correct cut is infinitely better.
#2. Cutting The Steerer Tube
If using a hacksaw, carefully slice through the steerer tube along the level line you marked.
If using a pipe cutter, line up against your mark and rotate for a clean cut.
If you’re cutting through a carbon fiber steerer tube, try not to apply too much force as you cut through as this can cause the fibers to fray.
Preferably, you should use a carbon-specific blade too. These are coated with fine cutting grit rather than the jagged teeth of regular blades. You can get away with using a regular blade on carbon, but you increase the risk of damage.
A helpful trick when cutting carbon fiber is to wrap electrical tape around the steerer tube against the cut line to protect against fraying.
Note that if you’re cutting carbon fiber, you should wear a face mask and cut outdoors, as the dust can irritate skin and lungs, and be a fire risk if if penetrates electronics.
Finally, you’ll want to use your metal file to work out any sharp edges which you don’t want to take out onto the road. Again, if cutting carbon fiber, go very gently.
You can also gently sand the tube and edges with gloves to deal with any remaining sharp edges.
With that done, you can replace the spacers and stem, before screwing the stem cap back on top. With the spacers you’ve fitted, you can make small handlebar height adjustments in the coming weeks.
Once you’re confident in the handlebar height remove any remaining upper spacer and once again cut the steerer tube down to the final, correct, length.
What If My Steerer Tube Is Too Short? 3 Options
So cutting down a steerer tube is one thing, but what if the steerer tube you have isn’t long enough?
Note that if you’re riding a bike that fits the rest of your body, the steerer tube is unlikely to be too short – assuming it’s not been cut down drastically by a previous owner. And if everything feels too short, you should probably be riding a frame in a larger size.
However, if it is just the steerer tube that comes up short, read on.
You’re likely to find yourself in this position if you’ve bought a second-hand bike and the previous owner has cut the steerer tube shorter than your desired length.
So, if you can’t “un-cut” a steerer tube, what can you do? You have 3 options.
#1. Buy a new fork
This is the simplest, safest, and best answer – and it’s also the most expensive.
As mentioned, the steerer tube is one part of the front fork as a whole, and the most straightforward way to get a longer steerer tube to work with is with an entirely new fork.
It is technically possible to remove a steerer tube from your fork and fit a new one, but it requires specialized tools, and you risk damaging the fork if you get it wrong.
It’s not advisable, and most manufacturers make a point not to sell replacement steerer tubes.
Fork failures are very dangerous for riders, and a common reason for model recalls, so we strongly recommend you don’t compromise your fork with this tricky procedure.
Research shows strong, uncompromised front forks are essential for bike stability, especially at speed.
If your second-hand bike’s steerer tube has come up short, use some of that money you saved buying second-hand to refit a new fork.
However, if this isn’t right for you, there are other, cheaper workarounds.
#2. Use A High-Rise Stem
If you’re coming up only a little short when looking to mount your stem, a high-rise stem could be the best answer.
These are stems with a more dramatic angle built into them, meaning the handlebars are positioned higher (or lower if the stem is flipped) than the top of the steerer tube.
By mounting the high rise’s angled stem to the steerer tube you can make up the length lost by a previous cut.
Most high-rise stems can elevate the handlebars by about 8-10 cm, which will usually cover the extra height you’re looking for for your handlebars. They might not look the prettiest, and you risk messing with your bike’s geometry if you go too extreme, but they get the job done.
#3. Use A Steerer Tube Extender
A steerer tube extender does what it says on the tin: it extends your steerer tube.
It slots into your steerer tube and extends past the cut point to give you more length to fit your stem onto.
Commercially available steerer tube extenders can give you up to around 10 cm more length onto your steerer tube, which should more than cover any length lost from a previous cut.
However, we generally don’t recommend steerer tube extenders.
By compromising on the integrity of your front fork, you’re putting yourself at risk – accidents without proper strength at the front of your bike are very dangerous.
So if you’re looking into extending that steerer tube, we humbly suggest you reassess and go for a new front fork, a high-rise stem, or a different bike.
Unless you’ve got a steerer tube that’s been cut short to the extreme, if you find yourself considering using a steerer tube extender, your frame is probably not the right size for you.
Now You Know About Bike Steerer Tubes…
Optimizing your setup can be fun and engaging, and finding new ways to rework your gear for a better riding experience is rewarding.
However, this must always come second to riding on gear which is reliable and safe.
And now you’re all caught up on the steerer tube you can get your setup perfected take it out on the road!