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How To Cut Carbon Fiber

February 01, 2023 4 min read

As BMX Racing technology advances, carbon fiber is becoming more prevalent on high-end race bikes. We get questions all the time about if you can cut your carbon fiber products. While we don't suggest sawing your VISION F1 PRO XXL toptube into a PRO XL (just jokes) You CAN cut your carbon handlebars and Carbon steer tubes. 

Today, we'll show you the proper way to cut carbon components to make you're ride truly tailored to you! 

When To Cut Your Parts

Before we show you how to cut your parts, let's briefly cover some scenarios where you would want to think about cutting. 

Trimming Bar Ends

Supercross Carbon handlebars come in standard widths depending on the size you purchase. The 'width' is the distance from bar end to bar end, and will determine how far apart your hands are when riding. Handlebars are produced on the wider side to give people the freedom to customize overall width.

With that being said, you don't have to cut your bars. The standard widths are designed for BMX Racing. But some riders may find increased comfort with a narrower bar setting. 

The following can go for any handlebar (Carbon or Alloy) but we suggest you ride with the new handlebar at its default width for a day or two before trimming. This will give you a better idea of how much to cut off if you even want to cut them at all. You may find the factory width to be perfect for you.

We suggest doing this first, because you can always go back and cut more off at a later time. But if you cut too much too early, you're stuck with a super narrow bar that isn't comfortable for you. 

Trimming The Fork Steertube

Trimming the fork steertube applies to our non-Pro sized carbon racing forks. Seeing as these forks can be fitted onto various bike sizes and accommodate a wider range of riders, the steertube comes a bit longer to ensure proper installation. 

We see some parents building bikes where the steertube sits 3"- 4" above the stem. It's pretty dangerous to leave the steertube this high as it's a potential hazard in a crash and can really hurt your rider if they fall on it. For that reason we suggest you trim the steertube to be 1/8"-1/4" below the stem or top spacer. 

We know that some of you worry about the trimmed steertube impacting the resell value, but this isn't the case. Your fork will still sell just fine as some poeple will be happy to buy a pre-cut fork since it saves them the effort. The primary objective is to have a safe platform for your rider.

How To Cut Carbon Fiber

Now onto the process of cutting carbon fiber and the best way to do it!

Tools You'll Need

- Carbon Blade

- Face Mask

- Cutting guide

- Measuring tool

All of the tools mentioned above are vital for a smooth and effective cut!

Firstly, you'll need a carbon specific blade. You may be tempted to use whatever blade you have sitting around the garage, but we strongly urge against that. In most cases, these blades are designed to cut wood or steel. The tooth pitch and and number of teeth on the blade will not give you a clean cut on carbon fiber. For the cleanest cut, you'll want to use a carbon specific blade. We sell a carbon blade from Park Tool, but you can also head to your local hardware store and find one there. 

We also suggest using a mask. As you begin to cut, small particles of carbon fiber will release into the air. The last thing you want to do is start breathing that stuff and getting it into your body. You wouldn't want to eat carbon fiber, so you don't want to breathe it in!

The cutting guide and measuring tool are pretty self explanatory. You'll want to actually measure what you cut so that both side are the same and you don't have a lopsided handlebar or accidentally cut your steertube too short! The cutting guide will ensure your blade stays straight throughout the cut so you don't cut off too much or too little. These two just tools take the guess work out of the process and help guarantee success.

Measure Twice, Cut Once!

The old age saying still rings true today. You can always remeasure, but you can't undo a cut. So make sure your marks are EXACTLY where they need to be before picking up the saw. A silver sharpie works great for marking your cuts on carbon. The silver mark stands out against the black carbon surface for the best visibility.

Once you have your marks set, throw on your mask, attach the cutting guide, and begin your cut. Be sure to hold the product in a secure manner, but remember to never clamp carbon fiber! Take your time and monitor the cut as you go. Readjust as necessary throughout the process. 

And You're Done

Just like that, you've successfully trimmed your carbon fiber product. Be sure to inspect your cut and remove any burrs or excess material before reinstalling the product onto your bike. 

Cutting carbon fiber may seem like a daunting task at first. But if you gather the proper tools and follow these steps, it's just as easy as cutting anything else.

If you want to see what the boss man himself has to say about cutting carbon, be sure to check out the video below from our Youtube channel. Don't forget to subscribe while you're over there!

- Written by Jonnie Vance