From where I live (Philippines) , there seems to be no stock for 26.8mm seat posts. All other sizes are available except for 26.8mm; they don't even sell shims for that size. Currently I am forced to use a 25.4mm seat post on my bike.

Is it possible to use a 25.4 - 27.2 mm shim for that purpose? I've used beer cans and inner tubes for shims, but both options has led to the seat tube crimping as I tighten it down.

  • You would be better to get a shim of the correct wall thickness, You need 0.7mm thickness walls - so a 27.2-28.6 shim would be better (might need to file it down so its small enough diameter) .
    – mattnz
    Commented Nov 1, 2020 at 2:01

1 Answer 1


There are many different standards for seatpost size, and 26.8mm is one of the more-common ones. Its not rare.

I suggest you buy the right-sized seatpost. If your LBS won't order it, then look to buying one online.

A shim is a solution but as you found there are drawbacks too. Bodging a shim from a can is really only workable for 0.2 of a mm at most. More than that and you'd want a proper shim which is at least 100mm tall.

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