My bike has no rear suspension. So I thought of putting a suspension seat-post on it. Unfortunately the only suspension post available in my city is a 25.4 mm one. I have added some scrap metal to fix it for now. But it's still a little wobbly. What is the best way to do this ?

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2 Answers 2


There are seatpost shims available for a few dollars. You should get them easily in your local shop or online.

I use an aluminum shim in one of my bikes with exactly the dimensions you need, it works flawlessly and looks very clean. I got it for about 3.50 € (5$).

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  • 1
    Yes, the important thing is that the shim go most of the way around the post, vs just being on one side. And having a "lip" at one end (as the commercial ones will have) keeps it from getting lost in the seat tube. (Aluminum beverage cans are a good source of shim material.) Apr 15, 2014 at 13:34
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    As expected, no cycle shop in the city of Pune, India has heard of anything called shim. I finally put the rubber of a used tube to fit the post. Let's see how long it holds up. Apr 15, 2014 at 16:32
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    Try eBay search on "seat post shim", saw a lot of options.
    – Papuass
    Apr 16, 2014 at 9:41
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    @AyanMullick Rubber will not hold for long time - it's run dry on sun. Put in something made from metal.
    – Alexander
    Apr 16, 2014 at 10:42
  • @Alexander That is exactly what happened. I am thinking I abandon the idea and order a SR Suntour SP12 NCX. That is the only one our local importer can import. :( ..So my options are either a Rs.300 local made or a Rs.8000 high-end Suntour; no options in between. Apr 19, 2014 at 1:44

I did cut the 27.2 old one and the new one fits perfect inside it

  • 2
    Gerardo - this comment has been flagged for "length and content" Could you please use the Edit link to expand it? Perhaps include information on the tools you used to cut the seatpost (chopsaw, hacksaw?) and how you deburred it (file? something else?) Also how did you allow the frame's seat clamp to tighten down on the inner post - did you slot the whole outer seatpost ? If so, what was your method for cutting a slot in the metal? This answer is interesting and should be expanded and saved, not deleted for lack of detail.
    – Criggie
    Jan 15, 2018 at 8:04
  • You wouldn't modify the frame, you'd use a shim, but my reading of this answer is that Gerardo has turned his old 27.2mm post into a 27.2->25.4 shim.
    – Emyr
    Jan 16, 2018 at 17:24

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