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steel tubing diameters vs. Seat post diameters(2 posts)

steel tubing diameters vs. Seat post diametersgtx
Sep 8, 2003 10:43 AM
Question regarding steel tubing diameters vs. Seat post diameters. Does IF use 26.8 seat posts because they use small diameter tubing on their seat tubes? Where does the 27.2 "standard" come from--was this the standard for Columbus SL, etc., or for seat lugs in the 70s and 80s? Or do most builders have to put some sort of shim in there? My Ibis Mojo used custom OS tubing and has a 28.6 seatpost. And what is going on with this Steelman seat tube?
Wall thickness.Spoke Wrench
Sep 9, 2003 8:15 AM
In order to get the required strength, bicycles made from crummy tubeing will have to have thicker walls than bicycles made from stronger alloys. Since the outer seat tube diameters can be determined by things like common derailleur clamp sizes, inner diameters tend to vary depending on the specific material used for the seat tube.