Originally Posted by
jackbombay
Mine are at 20mm.
Are the sides of slot in the back of the seat tube parallel to each other? The width of the slot is around 2.5mm or so, so if your ears are at 17.5 your slot is possibly nearly closed at the top?
Pinched seatpost binder
No, they were not closed, but were
not parallel. My calipers were measuring towards the outside of the tabs, inflating the error.
I expanded the seat tube with several different sizes of steel seatpost. I ended at 26.4, since 26.2 seemed to be the right size, but tighter than I wanted. What size seatpost does yours use?