Cutting steerer

wishitwasallflat
wishitwasallflat Posts: 2,927
edited January 2015 in Workshop
I want to cut a little off my Al steerer so its flush with the top of the stem. From all I have read you are supposed to cut perpendicular to the steerer. From the photo below hopefully you can see two black lines - the lower one is drawn on the steerer at the top of the stem, the upper one is the top of a 5mm spacer sitting on the stem. Hopefully you can see that neither line is perpendicular. The stem is an adjustable tilt specialized one and the top of it sits at a slight angle - not perpendicular - to the steerer. Would it be ok to cut 3mm below the lower line, I wouldn't have a perpendicular cut but I would be able to have the top-cap flush on the top of the stem for a neat finish. If I must do a perpendicular cut I reckon I would cut between the two lines, keeping below the top line so that if the 5mm steerer was left in place I could still pretension the headset - is that better?

Any advice on what's best would be very much appreciated.
IMG_0137_zps3dbc38a9.jpg

PS - I didn't make the original wonky cut that's there!

Comments

  • jgsi
    jgsi Posts: 5,062
    Whether you want to leave space for a 5mm spacer on top just for argument's sake is up to you.
    But
    Dont cut the steerer at an angle!
    Just don't.
  • wishitwasallflat
    wishitwasallflat Posts: 2,927
    JGSI wrote:
    Whether you want to leave space for a 5mm spacer on top just for argument's sake is up to you.
    But
    Dont cut the steerer at an angle!
    Just don't.

    Thanks I would prefer not to leave the spacer - but - what worries me is that a perpendicular cut 3mm below the level of the top of the steerer means that the front of the stem clamping area will be above the top of the steerer by those 3mm plus the height diff created by the upward slope of the stem top. Does that not matter? In my ignorance I am thinking that means the stem is not clamping down entirely onto steerer is that ok?
  • jgsi
    jgsi Posts: 5,062
    It is the star nut or the bung that is making the whole thing steady as a rock when you tighten up... remember you are tightening up the headset not clamping the stem as such... but I may be describing that in a bit of a cackhanded way.
    My Caad10 uses a bung system and it is allows for a flush fitting of the top cap and sufficient keeping the headset sweet and no play.. I dont know about yours.. it may need that small spacer.
  • wishitwasallflat
    wishitwasallflat Posts: 2,927
    Thanks it's an All steerer so no bung it uses a star fangled nut. Don't think it needs a spacer above, AFAIK that's only for carbon steerers. Maybe carbon ones need a spacer above cause they can't take the little gap that's left if cut perpendicular and stem doesn't sit perpendicular? Can't find anything on it on the www.
  • 6wheels
    6wheels Posts: 411
    If it's the multi-position stem with the shims to adjust the angle, I've just put one on my Synapse.

    I treated it like any other stem, as long as there is enough stem or spacer above the steerer (3mm), then it should be fine. The top cap is slotted and can be moved forwards and backwards, which will allow you to even the gap out after you've tightened the stem up.

    As JGSI mentions definitely cut it square.
  • Elfed
    Elfed Posts: 459
    Cut it square and use some pipe cutters, you'll get a nice neat edge that won't need truing or de-burring.
  • wishitwasallflat
    wishitwasallflat Posts: 2,927
    Ok folks many thanks and perpendicular cut it is.

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