I have 2 Bike Fridays both used seat post sizing shims and a smaller common 27.2 seat post..

sources (wholesale to shops) 'Wheels' and QBP, in the states..



I kept the seat post out of my AlAn, and used it in a steel frame, with a similar shim.

in that case the shim sleeves came from the British USE company.. they made few sizes of seat posts ,
and offered shim sleeves with ID of 25.0 and 27.2..

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