24 - 23.8 = 0.2mm, so you need to be be taking off 0.1mm of wall thickness
you can also ream out the bore of the seat tube with a 25mm reamer or drill bit in the drill press
1" is just a bit bigger at 25.4mm.. Kalloy makes 25* & lots make 1" seatposts..
*Campag makes 25mm seat posts too, My AlAn bikes used a 25mm seat post .. but I doubt you want to spend that much..
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Last edited by fietsbob; 10-21-17 at 03:49 PM.