Originally Posted by
Rick
My custom Co-Motion Pangea Rohloff brand new had the seatpost sliding down over time. I had things checked out at a bicycle shop and they claimed that the sizes were correct. I believe it is possible that the Thomson seatpost was flexing under my wight or the mechanics lack of skill and knowledge of tolerance's kept the problem from being solved. I changed to a Nitto 92 seatpost and the appropriate seatpost shim and a Phil Wood seatpost binder. I also tighten the binder bolt between 6 and 7 newton meters. This solved the Problem. The Park assembly grease destroys the anidasion. This doesn't look good at all.
Having used Thomson seat posts on many of my bikes for many years I have had zero problems with them slipping including on a Co-Motion and I am not a light rider at all in any sense. I have to imagine there was a torque issue or they did something wrong in spec'ing the post. My Cascadia is a 27.2 and I have a 27.2 Thompson Elite set back with original clamp zero shims and no slipping ever. I probably used either Park or Phil grease and zero issues there with anodizing. No issues with the anti seize either and any of my posts though my road bike has a Ritchey Classic (as it fit the aesthetics better and I was buying a bunch of stuff from them so it all matched). That seatpost looks like it could be brand new if I did some cleaning on it. I have never had any issues with anodized parts and anti-seize paste and I have 3 titanium bikes and love anodized parts.
Sorry you had issues but I think there is something else at play here. I am glad it is fixed but I would potentially go to a different shop or a different mechanic. Using the proper paste and proper torque and a good seatpost collar you shouldn't have issues unless the frame is buggered. If the anodization is failing then there might be a different issue and it could be the anti seize but I would be doubtful. If it is carbon fiber grip than potentially that could wear off coatings if given the chance to abrade but if properly torqued it shouldn't move at all.