Have a thomson post in an alu frame, been just fine for a couple of years bit has started slipping down. Can a seatpost wear out? Might it be the clamp needs replacing? Have it pretty tight already and have taken some of the grease off it, don't really want to over tighten it. Ta

clean the seatpost & seat tube, regrease post & refit

Yep, done that

New clamp time then I reckon.

I have had exactly the same problem with my Thomson Elite 27.2 x 410mm in an Orange P7 frame. It was fine when I first built the bike up and was amply retained in the frame with the supplied QR clamp. However, come July this year, it started to slip through however tight I had the clamp up. I tried a non-QR clamp but it still slipped. I managed to shear the bolt in the clamp, trying to stop it slipping.

I made sure it wasn't just me who was going mental and tried a mate's 27.2 post in the frame with the QR clamp and it didn't budge a millimetre. Upon further investigation I discovered that the diameter of the post wasn't 27.2mm at any point (measured it with a pair of recently calibrated calipers). The inch or so around the clamping area was actually a good .1mm out. Doesn't sound a lot but it was enough to allow the post to move from side to side in the frame. Not much good when it's supposed to be an interference fit.

I phoned Merlin (the original vendor) and they told me to send it back to them. Frankly, Alan, the manager there was most unhelpful and dismissive of my problem. He tried to tell me that 'all' of the 27.2 posts they had were at least .1mm out. I was told that there was nothing further they could do and that they would not provide a new seatpost under warranty. I insisted that the post be sent back to Jim Walker (UK importer) who were much better to work with. They turned my claim round within a couple of days and got a brand spanker out to me no questions asked. Unfortunately it had to go back through Merlin so took another 5 days to get to me.

In short, it's not unheard of so insist it goes back to the importer for a claim. Hope that helps.

*and relaaaxxx*

thomson posts do have very fine grooves running down the surface of the post and these do wear after a while, having said that there should be enough give on the seat tube to still tighten??

I had the same problem as rob arnold, ended up buying a new post.

i suppose once those CNC marks wear off the post will be a bit under sized compared to original.

i can't imagine they wear any quicker than the cheaper, extruded posts or a carbon one. I'd go for a new seat clamp.

Thanks, will try switching clamps, otherwise maybe new post time

same problem, swapped to a wider collar qr clamp instead of a bolt up and the creaking and slipping stopped

Surly Constrictor seat clamp and never worry about it moving again 🙂

SSP

Sorry for the double post, hamsters are tired.

SSP

Try putting some of that carbon paste on it instead of grease. As in take it out, fully degrease it, ditto the frame then spray on the carbon paste stuff and I'd say it won't slip any more.