How to:

Cut down a steerer tube.

What you’ll need:

Hacksaw Saw Guide or Insulating/masking tape Scribe/Screwdriver/Blade De-burring tool/Files

Method:

If you’re removing spacers from an existing setup, remove your stem cap and arrange your stem and spacers as you please. (Note: when cutting make sure you know where your star fangled nut is – you don’t want to chop it in half!) If you’re installing new forks, slide them in dry (i.e. without grease on anything) ensuring you’ve got all your headset parts in place, compress it as much as you can by hand and do everything up how you want it.

Once this is done make a mark where the top of the stem comes to on your steerer tube.

Remove the forks (removing the brake and wheel also helps) and clean them up. Don’t try and get away with not having to clean and re-grease them, because there’s a 99% chance they’ll get covered in filings anyway.

Measure 5mm down the steerer from the mark you made and make another one, like so:

If you have a saw guide - use it, if not, then wrap some tape around the tube where the lower mark is as a guide for cutting. The idea with the tape is the straight edge - if you don’t wrap it perpendicular to the tube, the edges won’t meet up, for this reason its better to use tape that doesn’t stretch. Make sure there’s a decent overlap so you can guarantee you’ve got it straight.

Clamp your forks in the vice. If you’re using a metal vice, use some bits of wood or jaw protectors to avoid damaging your forks, and whatever you do – DO NOT SQUASH YOUR FORKS! Nip the vice up and get someone to support them if you’re having trouble.

Tips for n00bs: Practise on an old bit of tube or pipe first, if this fails miserably take them to your LBS. To get the cut started put your thumbnail up to the point you want to cut as a means of stopping the blade slipping. Remember – a saw blade is directional, it cuts while moving forwards (assuming the blade's in correctly) so pushing down on it with all your might while cutting does absolutely nothing at all to speed things up, Just use a decent blade, take your time and keep checking it's straght and it should be fine.

Warning! Do not ignore you own How-To and cut through your star fangled nut!

With the end now cut off, remove them from the vice and check your handiwork. You might need to square the cut off with a file so stick them back in the vice with the steerer pointing straight up. File the steerer up to the tape with a nice wide flat file. Check by eye for the most part but you can use a square to check its straight when you’re getting close to your mark, although if we're honest is not the end of the world it it's a bit on the piss.

De-burr the inside and outside of the tube with the be-burring tool/file. You don’t want a huge chamfer on it, just a nice clean edge.

Brush/wipe away any filings, re-grease & refit.

Extra Tips:

You can always grind the steerer down instead of cutting it, this is a better method if you need to have a slash cut steerer, as you can mark out as above and carefully grind down to that line.

You can also put tape round the steerer to mark it out.