How to Measure Fork Tube Diameter?

Whether your bike is old or new, chances are you will have to replace parts of it from time to time. And I came to that realization after my local bike shopkeeper told me that my bike’s fork tube needs to be replaced.
But to replace it – I will need to buy a suitable one at first, and for that, knowing the exact measurements of my existing fork tube is necessary. Oblivious to how I should do that, I started researching on how to measure fork tube diameter.
And to my surprise, all you will need for the process is a measuring tape and to take some time off your day. I have elaborately discussed it right here, just for your convenience.
What Is a Fork Tube?

Before we get into how you should be measuring the fork tube diameter, we will discuss a little about what a fork tube is, to begin with.
For starters, the fork tube of a bike basically holds the front wheel into its place. The reason why it is called a fork is that it contains two blades, which are joined using a fork crown.
The tube attaches the fork to the bike itself, while the rider gets to steer the bike comfortably using the handlebars. The diameter of the fork tube keeps on varying depending on where you are measuring it – and now we will get into how you should measure it.
How to Measure Fork Tube Diameter?

The diameter of a fork tube is rather important – especially, you need to know it accurately when you are about to change your bike’s fork. And to make sure you do it without any error, we will be guiding you through the steps right here.
- Unmount the Stem
The fork tube in your bike is connected to the stem. And for you to measure it accurately and effortlessly, you will have to unmount the stem of the bike. For that, you will have to loosen the stem binder bolts at first and then proceed to remove the stem before measuring.
- Gather a Measuring Tape
The handiest and most important tool you will need throughout this process is a measuring tape. Although, getting accurate measurements from a measuring tape can be rather difficult in this case – given the diameter of a fork tube is quite small.
So, to minimize errors, you can take the same measurement a few times.
- Measure the Outside Diameters
You will have to take measurements of the fork tube in two different places – first, measure the outside diameter of the section where the stem clamps around.
And second, measure the outside diameter of the bottom section, where the steerer is connected.
- Write Down the Information
After measuring the outside diameters, you can measure the angle of the fork tube with the crown race, which is built-in mostly. Once you have gathered all the information, it is time to write them down.
If you are looking to replace your fork tube, then you will need to note down those numbers accurately – or else you won’t find a proper replacement.
Final Words
Learning how to measure fork tube diameter is not the tricky part – the tricky part is to actually find a new fork tube of the exact same diameter.
To make that easier for yourself, surely measure the diameter properly, and do it a few times so that you can be absolutely sure about the numbers.
This video may help you to measure your bike tube by your own