Are seatpost shims safe to use from the perspective of the frame, seatpost, and the rider?
My concern is that seatpost shims only support the seatpost for a few centimeters - while a properly matching seattube will support the seattube for the entire depth. Would this increase stresses on the seatpost or the frame?
And would this be an argument for avoiding short shims and trying to get as long as possible?
Related but with no relevant answers: Is it safe to use aluminium seatpost adapter (27.2mm to 31.6mm) for a carbon frame?