Why You Might Need to Cut Your Seatpost – and How to Do It Safely

When we build our bikes, we set the seatpost length to suit the frame size, allowing for a bit of adjustment up and down, however, we can’t cater for every individual’s exact fit. That’s why, instead of offering different seatpost lengths, it’s common practice in the cycling industry to simply shorten the seatpost if needed.

We don’t cut the seatpost in-house because, once it’s been trimmed, you can’t add the material back on. Until you’ve ridden the bike and set your ideal saddle height, it’s impossible to determine the exact length required.

The good news? Cutting a carbon seatpost is perfectly safe and won’t void your warranty—as long as it’s done properly. If you are uncomfortable doing this yourself, your local bike shop will be more than happy to help.

 Here’s how to do it:

How to Cut a Carbon Seatpost

What You’ll Need

• Fine-tooth hacksaw (ideally with a carbon fibre-specific blade)
• Vice or clamp (to hold the seatpost)
• File or sandpaper
• Electrical tape
• Cloth
• Protective gear: dust mask, gloves, and eye protection
• (Optional) Carbon paste

Step-by-Step Guide

1. Remove the seatpost – Loosen the seat clamp and take the seatpost out of the frame. If your bike has internal cables or a Di2 battery inside the seatpost, disconnect and remove them first.
2. Clean and mark – Wipe the lower end of the seatpost clean, then mark your cutting point with electrical tape wrapped around it to create a clear guide.
3. Secure in a vice – Wrap a cloth around the seatpost to prevent scratches, then secure it in a vice or clamp.
4. Cut carefully – Wearing safety gear, use your hacksaw to cut along the tape line. Carbon seatposts cut quite easily, but take your time to ensure a clean cut.
5. Smooth the edges – Use sandpaper or a file to remove any rough edges.
6. Clean up – Remove the tape and wipe away any carbon dust.
7. Reinstall – Apply a small amount of carbon paste if needed, then reinsert the seatpost, reconnect any cables or battery, and set your saddle height.

Important Consideration

The minimum insertion for any seatpost is 100mm—this ensures both the frame and post maintain their structural integrity. If you've shortened the seatpost, the original "Minimum Insert" marking will no longer be accurate, so double-check before setting your saddle height.

With these steps, you’ll have a perfectly fitted seatpost, ready for a comfortable ride!