so after some problems with seatpost creeping down, I bought some carbon paste stuff and appplied to thomson post in steel frame (RL 853). It certainly tightened up with a lot less force and didn't move at all during a 3 hr ride, but what was previously silent became a creaking nuisance – any ideas.

I'm guessing it was just the flex of the interfaces, maybe I should have only applied it on the bit that is clamped, rather than the full inserted length ?

cheers

Are you SURE the post is the right size for the frame? Creaking may be coming from elsewhere i.e front mech clamp?

Creaking way more likely to be coming from elsewhere.

I found that it was my seatclamp/frame interface causing problems when I had similar issues recently.

definately post and carbon grease – when running without there is no noise and if I do clamp – it's a bolt, not qr, up really tight and post and tube are clean, then no slippage. When I put some carbon grease on the post the bolt needs less torque but there is a creaking – in fact, you can hear it creak when tightening the bolt (this does not happen without the carbon grease).

Last ride I cleaned it all off and the creak was gone, so that is definately the source.

Post is definately the right size and there is no wear on it.

I am wondering if it's something to do with the little sand like particles on the grease changing the metal to metal interface

when running without there is no noise and if I do clamp – it's a bolt, not qr, up really tight and post and tube are clean, then no slippage

I'm confused – there's the answer above.
Are you worried about how tight it has to be?

…and yes, a solution would be to just do the clamp up really tight and have no grease in it at all, but this is meaning that the clamp bolt is bending as so tight, which may not be a problem ? http://www.singletrackworld.com/forum/topic/rl853-owners-seat-clamp-query

What paste is it that you are using?
Tacx, Effeto, Finishline, Pace….. ?

tighten it with carbon paste to the same tightness as when you were using grease?

I've not tried all the different brands on the market, just Tacx and Ritchey, but have had this problem on different bikes. Carbon paste is meant to induce friction so its not surprising that on some combinations it can induce creaking where there's still a tiny amount of movement.
Carbon frame/alloy post was worst for me, but carbon/carbon, I could use the paste with impunity. ❓

What you could try is to put a thin stripe of grease down the front and back of the post, where the movement is probably happening, then put stripes of the paste down the sides, where most of the grip from the clamp is needed. Dont rotate the post as you slide it in obviously.
This still might not work, I'd try using a very thin layer of grease otherwise…

I had an inbred with a Thomson post that did this.
I took a half round file and lightly roughed up the inside of the seat tube.. turning it round, rather than up and down.
Worked for me. 😀

Thanks all. Tacx paste is what I used. just been out for a ride with nowt on it and all seems ok, so will keep a wee eye on it

cheers

Hi

A late suggestion – have you greased the seat collar bolt? Doing it less tight with the paste may let it move enough to creak… Use some copper slip or similar. If tonight's ride was wet, and it was not creaking, there's your answer.

good point, and yes it was very wet ! will stick some copper slip on the bolt tomorrow (does have some light grease already) as hoping to ride in the evening again, cheers

Aye, grease the bolt was going to be my suggestion, if you can hear it creak when you tighten it that's the likely culprit.

Alternatively, just do it up slightly tighter, not as tight as it had to be with grease, but there's no real advantage to running it as loose as it'll go without slipping!

Had this happen to me, tightened the clamp on the seat rail and it stopped creaking.