Trimming a Carbon Fork Steerer - will this work?

JJDLD Posts: 75
edited October 2008 in Workshop

I need to cut my carbon fork steerer tube down a bit (it came uncut). I've got the stem to the right level, but intend to leave a couple of 5mm spacers above for any future fine tuning in case the new position proves to be too low (I think it will be fine, but it's always better too long than too short :) ).

For the trim, could I leave the fork in-situ on the bike with one 5mm and one 2.5mm spacer above the stem (the 2.5mm one being metal), and simply cut across the top of the 2.5mm spacer (i.e. using it as a cutting guide)? Once cut, I'd replace the 2.5mm spacer with a 5mm to get the required stack height and have the required gap between the top of the steerer tube and the steerer cap.

What could possibly go wrong (bearing in mind that I don't have £300 to replace the forks if it all goes pear-shaped...)?




  • It sounds like a good theory. I've only done it once. This was the reply I got to my question about it, and I followed this advice: ... highlight=

    It wasn't too bad - a bit stressful - but the accuracy of the cut isnt super critical - you can be out by a milimetre as far as I can see. I did accidentally cut all the way through and a tiny part of a layer peeled off, so be careful. I'm hoping that doesnt matter too much :? .
  • Your method is sound. Use a 32tpi junior hacksaw and WEAR A DUST MASK
  • nicklouse
    nicklouse Posts: 50,675
    and use old spacers.

    I would still prefer a clamped guide.

    Got an old stem?

    Mark the steerer, remove, fit old stem and cut.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • Gav2000
    Gav2000 Posts: 408
    nicklouse wrote:
    and use old spacers.

    I would still prefer a clamped guide.

    Got an old stem?

    Mark the steerer, remove, fit old stem and cut.

    I cut mine a couple of weeks ago using an old stem (as advised by someone on this forum) clamped in place to act as the guide. I scraped the old stem as expected but got a cut so clean and flat it looked no different than the fork.

    Like a streak of lightnin' flashin' cross the sky,
    Like the swiftest arrow whizzin' from a bow,
    Like a mighty cannonball he seems to fly.
    You'll hear about him ever'where you go.
  • I borrowed the guide from my LBS. They were quite happy as I'm a regular and I took it straight back. Makes the job a doddle, although no reason why a spacer won't work nearly as well!
    JJDLD Posts: 75
    Just an update...

    I trimmed the steerer tube using an old stem as a guide as suggested. Not the smoothest cut in the world - I found that the blade of the hacksaw had a tendancy to slice in to the alu of the old stem (probably due to my cack-handed handyman skills) - but hopefully it will do. If I had to do it again, I think I'd put a steel washer on top of the stem, to try to keep the hackwas on a more level path.


  • maddog 2
    maddog 2 Posts: 8,114
    I always use the old stem method. Works okay, just go slowly.

    Having said that, I do really fancy a proper guide. Next time I have a tool buying spree it will be on the list.
    Facts are meaningless, you can use facts to prove anything that's remotely true! - Homer
  • Monty Dog
    Monty Dog Posts: 20,614
    My only comment - use the underside of the stem clamp as a guide - the damage isn't so obvious should you need to use it again! A wrap of thin tape around the steerer also holds the fibres together and scoring a the cut line first with a sharp knife keeps the cut cleaner too.
    Make mine an Italian, with Campagnolo on the side..