I’m contemplating gluing my seatpost into my Giant Advanced carbon frameset. Bear with me on this.
The top part of the seatpost has not cracked but is flexing, like a carbon fishing rod, hence the paint crack and no carbon crack. (I’ve removed paint from this area to verify this). The lower, assumed paint crack, is a result from the bottom of the Thompson seatpost. The frame does not have any noticeable flex or creak even with my 16.5 stone bulk.
I’ve changed the seatpost today, from a Thompson 410mm, to a Gusset XXL – 450mm long. That’s 180mm in the frame / 270mm sticking out. However with both this and the Thompson post you can pivot the post in the frame, before clamping, indicating a slightly larger diameter to the seat tube below the “clamping zone”. Hence the corresponding paint crack lower down on the tube. I want to eliminate this to gain full benefit of having more seatpost in the frame . I was thinking of a low viscosity epoxy adhesive, maybe too thick, or alternative a carbon assembly paste. I’ve also got to get it past the “clamping” zone which will act like a wiper.
Or just ride it until it breaks.