cutting carbon steerer

by lazyusername   April 20, 2012  

I've got to cut the steerer tube on a new build shortly, it's carbon. Have never cut the steerer tube myself before, is it going to involve more than a hacksaw and a pipe cutting guide to get it straight?

Are there any pitfalls I should be aware of?

11 user comments

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just cut mine using a pen and a hack saw. Just go for it bro

posted by SammyG [290 posts]
20th April 2012 - 20:24

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Hi, I have always used a wide masking tape slowly wrapped around the tube once you know where the cut is to be made. Being wide and used with little tension it will keep the tape line straight. If both ends meet perfect then your cut guide line will be correct.
I use junior type hacksaws on carbon, but don't just go from one point, slowly revolve the tube lightly sawing as you go. Once you have a good guide line it is just a matter of folowing this carefully around making the cut deeper as you go. Finaly finish with a light file. Sometimes just sawing straight through with a large hacksaw CAN splinter the carbon and send a sliver down the tube - you don't want this. Take your time and you will be OK.
There are special 'clamps' that can be bought, but if its only the one the above method works well.
I have used this for 'donkeys' on carbon, aluminium and steel without issues.
Hope this helps.
Regards

Trikeman. Wink

Grunt, puff, pant and groan goes the old man - but he gets there in the end. ;o)

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posted by trikeman [346 posts]
20th April 2012 - 20:55

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I'm glad I didnt know that before I went to town on my steerer trikeman as it would have taken forever!

posted by SammyG [290 posts]
20th April 2012 - 21:22

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Park do a specific hacksaw blade (CSB-1) for carbon steerers, it has a grinding surface instead of teeth so it's kinder to the carbon. trikeman's advice about starting the cut all the way around the steerer first is well worth following too.

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posted by Dave Atkinson [7034 posts]
20th April 2012 - 21:31

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Buy a Carbide Grit Hacksaw Blade for your normal hacksaw - much cheaper than buying the Park one.

posted by garyh [34 posts]
20th April 2012 - 22:22

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Yep - good advice in here. I was a bit anxious about it initially, but tbh it was pretty easy.

When I cut mine down I used masking tape, drew the cut line on that and made a shallow cut all the way around with a jnr hacksaw blade. Once the shallow groove was there I used light pressure and made the cut. It went fine.

Use a fine grade of wet & dry paper to put a small 45 degree chamfer on the new top edge. That looks neat, and helps the stem & spacers to slide on easily. Use a mask or keep your head away from the carbon dust.

Make sure when you measure you cut it low enough for the top cap of the aheadset to have a couple of mm of free space to tighten down on the headset stack. Last thing you want is a lovely neat cut that doesn't let you adjust it properly.

posted by thereandbackagain [151 posts]
20th April 2012 - 22:25

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dont get too worried. A junior hacksaw with a high TPI, a cutting guide and some tape round the steerer where you are going to cut. I have done 2 successfully and have always cut straight through. The carbon will split badly if you don't put the tape on. Just take your time, and slam that stem!

posted by matt637 [52 posts]
20th April 2012 - 22:37

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Thanks everyone

posted by lazyusername [140 posts]
21st April 2012 - 7:47

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Just cut my steerer, as suggested here I used a high TPI blade. As a guide I used and old defunct stem seem to work perfectly.

posted by Amos [41 posts]
21st April 2012 - 7:57

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Just a word of warning don't be too keen to cut your steerer. After cutting mine down I rode the bike for a while and thought it was a bit too low. Which is a bit tough after you have cut it! On my other bike I cut it longer and left some spacers on top of the stem to get used to it before deciding to cut to size.

posted by SideBurn [731 posts]
21st April 2012 - 9:29

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Having just given this a go i would add two points which may/may not be useful or obvious!

1. A new fork is really long so have a practice further up!
2. If you cut from one point all the way through its very hard to not cut at an angle. So the shallow cut all the way around and Trikeman's point about revolving the tube as you cut is definately helpful

posted by 02curtisb [52 posts]
5th June 2012 - 11:27

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