How to cut your steerer tube
What is your steerer tube and why might you need to cut it?
A steerer tube is the portion of your fork that extends from the crown and connects the fork to the frame. On mountain bikes it is typically made of Aluminum or Steel and it can be cut to different lengths in order to fit different frames and rider preferences.
The steerer tube comes in a long length from the factory to allow for a customized fit by the rider. They are also often replaceable in case one is too short when changing frames or other various scenarios.
What tools will you need?
- Hacksaw with a sharp blade or a pipe cutter
- A flat file
- A star nut setting tool
- A chamfer cutting tool
- A scribe or marker
- A cutting guide
- A vise
- Gloves
A couple of things to consider before diving in.
- Have you tried your bike with the stem at your desired height?
- If you have a star nut in your fork already, is it pushed far enough in to avoid getting cut off?
- Never cut the steerer tube while your fork is on the bike
*This can cause unnecessary strain on the frame and put metal shavings where they don’t belong.
Step 1: Prep your tools.
Step 2
Measure your steerer and make your reference mark.
Insert your fork steerer into your headtube
Install your required dust cap and desired spacer amount
Install your stem
Using your marker or scribe make a mark flush against the top edge of your stem
Step 3
Remove the fork from your frame and determine your cutting height.
Set your stem, spacers, and dust cap off to the side
*If you want your top cap to sit flush against your stem you will need to subtract 3 millimeters from your current reference mark before cutting. This will give you the necessary space to preload your headset
*If you want to have as much margin for error as possible, you can cut your steerer tube at your current reference mark(the top of the stem). You will need to add a 2.5 millimeter spacer under your top cap to allow space for preloading your headset.
Step 4
Before cutting, double check all your measurements.
*It is much easier to remove more material but if you cut it too short and need to increase the length of your steerer it will cost significantly more time and money..
Step 5
If you’re using a hacksaw.
Place your cutting guide snugly in the vise
Insert the steerer tube into the guide and align your reference mark with the opening
Initiate one or two cuts into the steerer tube then stop
Here is a step which I like but is not 100% necessary. Loosen the guide clamp just enough to slide the steerer. With the cutting blade in the groove you just cut, slide the steerer until the blade makes contact with one side of the guide opening. This will give you a more precise line to cut against.
Most guides have openings that are wide enough for 2 or even 3 blade widths to prevent binding. This can lead to a drift in your cut. While not the end of the world, can be frustrating when you are OCD about your bikes
If you are using a sharp blade(which you should be) don’t push down hard on the blade. Let the teeth of the blade do the work for you.
Forcibly pushing down on the blade can lead to premature dulling of the blade and potentially the blade braking
Cut through the steerer until the end piece falls out the opposing side.
Push your steerer through the guide until the freshly cut edge extrudes from the opposite side.
Use the guide as a holder to support your fork while you use a flat file to remove any burs and smoothen the edges left from the cut
Step 5.1
If you’re using a pipe cutter.
Align the pipe cutter’s blade with the mark made at your desired height.
Begin to spin the pipe cutter around your steerer tube.
Slowly tighten down the blade after two to three turns
Apply pressure slowly here because cutting too quickly will dull your blade quickly and cause the cut to flare out causing fitment issues.
Once you have fully cut through the steerer tube you can grab a flat file to remove any burs or sharp edges left by the tool.
*Important note- DO NOT turn fork upright until you have cleared away ALL metal chips and debris. Dropping metal debris on to the lowers can cause major problems in the future.
Step 6
Use a chamfer tool to make it beautiful.
Insert steerer Tube into chamfer tool.
Spin the tool two full rotations in the cutting direction
Flip the tool around and do the same with the opposing cutting surface.
Step 7
Clean all metal shavings and debris off.
*Any metal debris left over that accidentally falls between the stanchions and the lowers will cause problems in the future
Step 8
Insert your star nut.
If you already have a star nut you can use a star nut setting tool to confirm you have the correct depth.
To install a new star nut, you can likely find the instructions for your setting tool on the manufacturer’s website.
They all work slightly differently but typically yield the same results.
Step 9
Reinstall your fork
*If you need help here you can reference our blog post instructional guide to doing just that, ‘How To Install Your Suspension’.
*Notes before we go- If this task seems daunting or you don’t have any of the specialized tools to do so, simply go to your local bike shop and ask for assistance. Most shops can do this while you wait and it won’t cost much. It’s a very simple process if the tools are present but can lead to a disaster if these tools aren’t available.
