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Hi all,
I have a Genesis Longitude 2016 and just noticed something. When the seatpillar clamp is completely loose and the seat post is inserted into the tube, there is about a 1mm or maybe 1.5mm of movement. I just bought a new Thompson clamp to replace the old one which was made from cheese. Torquing it down to the recommended 2.8N doesn't bite enough to stop the seat rotating by hand. Any idea what's going wrong?
Thanks!
FM
1-1.5mm is asking a lot of any clamp. I’d assume the post was the wrong size tbh- or possibly ovalised if the slop is different in different directions. Bear in mind there’s not a huge difference between 30.9 and 31.6 but they aren’t swappable. You haven’t lost a shim by any chance, have you?
Usually down to tolerance issues. Often find some posts are snug and some are not. If the ID (Inside Diameter) of the seat tube is on the high end of the tolerance spec and the OD (outside diameter) of the post is machined towards minimum then sloppy the fit will be.
Even posts from the same manufacturer can be sloppy or not depending on the time / batch of the production run.
I tend to use a bit of 3m metal tape to shim the tube out if it's sloppy...really thin (0.12mm) so you can tune the post fit with more or less complete wraps.