What we use in stubborn cases, and there's plenty of this with new proprietary bullshit clamps, d-shaped seatposts and out of tolerance frames is hairspray. But better be sure where do you want it because breaking the bond takes a lot of WD40 and swearing.
Better if you can try different seatposts and clamps, tolerances in the bike industry are so bad you may find something that works.
What we use in stubborn cases, and there's plenty of this with new proprietary bullshit clamps, d-shaped seatposts and out of tolerance frames is hairspray. But better be sure where do you want it because breaking the bond takes a lot of WD40 and swearing.
Better if you can try different seatposts and clamps, tolerances in the bike industry are so bad you may find something that works.