Seat tube shim adapters are quite expensive, what kind of material do you recommend as a shim?

I have seen in a thread some guys talking about home made shim:

  • paper tape
  • alloy drink can as a shim (aluminium or steel?)
  • Thin and quality paper/cardboard

Which one would be the best?

  • 3
    I would go with the pop/beer can. Among other things, the thickness of the metal varies with the height along the side of the can, so you can customize the thickness. And paper/cardboard will compress too easily and make a lousy shim. – Daniel R Hicks Mar 26 '15 at 11:07
  • @DanielRHicks Would you choose steel or aluminium can? Some says that aluminium won't slide that easily, but have no idea why. – JinSnow Mar 26 '15 at 11:11
  • 2
    Aluminum is easier to work with and "conforms", making it a better shim in most case. Steel will take wear a bit better in cases where the fit is poor. Aluminum will "stick" to steel in a way, which is probably good, to keep it from sliding around when you want it to stay put. – Daniel R Hicks Mar 26 '15 at 11:16
  • 4
    When you get the shim in place, make sure there's at least 1/4" or so showing above the top of the tube, then use a thin screwdriver to bend the top of the shim outward, to make a "lip" that will help keep it from falling into the tube. – Daniel R Hicks Mar 26 '15 at 11:17
  • Why shim, if you can buy the right sized seat post? – Criggie Sep 28 '17 at 0:24

Soda cans do the trick, cf this tuto

enter image description here

  • 3
    That looks like a recipe for a death by a thousand cuts! – andy256 Apr 21 '15 at 9:22
  • 2
    @andy256 - Well, one presumes that he'd put a seat on top of it. But there's no need for the "ears" to be that long -- 1/4 inch is plenty. – Daniel R Hicks Apr 21 '15 at 11:44
  • 1
    @DanielRHicks, You're right, this was an artistic touch! Quite nice, hey! – MagTun Apr 21 '15 at 12:24
  • @andy256 at least! – JinSnow Apr 22 '15 at 7:15
  • 1
    This is generally the right answer (I think), but I would not use an aluminum shim on a carbon-fiber frame and/or with a carbon-fiber seatpost, because galvanic corrosion can occur between CF and Al. – Adam Rice Sep 27 '17 at 22:18

Definitely alloy drink can or other thin sheet metal as it is not compressible and is not affected by water, oil or grease.


Try a rubber sheet cut to size and rolled around the seatpost. It won't slip. Just an idea.

  • 1
    If you have that much slop, you have the wrong-sized seat post. – Criggie Jul 11 '16 at 19:55
  • 1
    Welcome to Bicycles @Sally. Good to see you here. Since each site is different, I recommend that you take our tour and read through the help center. Then you'll understand why I say this should have been a comment. But I think it would be hard to the rubber in position, and the seat would still feel a bit loose. Hope to see another post from you – andy256 Jul 11 '16 at 23:11

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