At your size I wouldn’t bother.
Black Brompton telescopic with a carbon seatpost in the top might save some grams, not sure on diameter can check tomorrow.
The topper is 26.6, sjs sell a few or go Thomson - will be lighter than carbon, and get a slick clamp, the Brompton ones are functional but not “light”
@Rhobbs started
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At your size I wouldn’t bother.
Black Brompton telescopic with a carbon seatpost in the top might save some grams, not sure on diameter can check tomorrow.