Is that the direction the post goes down in? It doesn't look straight at all based on that picture amd the video.
Yes. I had to file down the inside of the seat tube so that the seatpost would fit smoothly and straight.
If you can only get get a certain amount of insertion of the seat post, and the restriction is caused by a constricting frame, you could cut the seat post shorter. I'm not sure what the minimum insertion amount that is required to maintain structural integrity, maybe someone else can chime in on that.
I thought about that too, but I managed to solve it.
Pour insérer la tige de selle il faut retirer une lame en metal qui s'insère entre le carbone et la tige de selle ( les 2 vis de serrage appui sur cette lame pour bloquer la tige de selle.! )
J'ai l'impression que sur ton cadre cette pièce n'existe pas... Peux tu faire une photo de l'endroit où rentre la tige de selle dans le cadre (sans la tige de selle).
The seatpost wasn't going in smoothly with or without the metal wedge you mentioned, but now after filing down the inside of the seat tube everything is okay.
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After finally removing the stuck seatpost and spending hours filing the inside of the seat tube, today I finally went to assemble the seatpost and saddle. To my surprise, when tightening the wedge bolts, the frame developed two cracks (as shown in the attached photo). I didn't even apply the recommended torque of 5 Nm and the frame cracked. I believe it's due to poor carbon quality or all the work to remove the seatpost ended up stressing that area where the wedge sits.
I contacted the seller to see what will be done now. When I told him that the frame had a factory defect, since I had to file the inside of the seat tube and the seatpost was stuck, he offered to send me another, smaller seatpost, but since I had already managed to remove the seatpost and file the inside of the seat tube, I said I didn't need it. Let's see what he says about these cracks in the frame...
Note: The screws on the wedge of this frame stick out halfway (see photo), they don't go all the way into the holes. Does this also happen with the replica frames you have? Because it doesn't happen with the original frame.