Is that around the bottom of the top tube? May be a little lip, and if the bottom of the ti post is cut of clean, rather than finished around the edge, it may be catching on a small lip, whereas the alu posts you have have a bevelled edge which lifts them over the slight imperfection rather than catches on it?
Is that around the bottom of the top tube? May be a little lip, and if the bottom of the ti post is cut of clean, rather than finished around the edge, it may be catching on a small lip, whereas the alu posts you have have a bevelled edge which lifts them over the slight imperfection rather than catches on it?
Just a guess but had something like this before.