what can i do to get my seatpost to stop sliding down into the seat tube?
i've got a merlin ti frame. i had a ti seatpost which gave me this problem, recently upgraded to a carbon post, same issue. the sliding into the seat tube motion has also scratched away the top coating of clearcoat?/enamel? off the post, i've tightened it fairly well, but i fear if i go any further i may crack the post. also... i'm not super overweight, 170lb, so i don't see my bodyweight really being an issue...

is there some sort of adhesive i can use that won't effect the post or the frame?

thanks in advance for any input.

TACX is a paste to put on carbon seatposts/frames to reduce slipping. If that doesn't work go buy a Thomson seatpost, their surface finish tends to prevent slipping, plus they are aluminum and lighter than many carbon posts

Try the paste, and put a second seatpost clamp on the seatpost itself. I've seen a lot of pro CX racers do that.

- Tacx carbon paste
- FSA Installation Compound
- Ritchey Liquid Torque

or

- Ghetto version: get something syrup-like (Gatorade) and put on seatpost

+1 on the Ritchey Liquid Torque. It will also prevent galvanic corosion.

EXACTLY the kind of feedback I needed!

Thank you.

before all of that ensure that the inside of the seat tube is totally clean and dry, use some solvent to get any residual slippery stuff out of there, that should solve the problem.

Wait. Wut?

Is this a common problem? How could something so fundamental as the proper function of a seatpost be such a frequent issue?

I use a short seat post length, given my frame dimensions, i don't need a longer one, and this just tends to be a recurring problem for me. if the liquid torque doesn't work, i'm just gonna go thompson. and yes, it is the right sized seatpost, 27.2, measured a while ago. not sure if it's a common problem for others, but it has been for me, the ti post in addition to slowly sliding down had trouble clamping my saddle correctly, so i went carbon, sliding is again an issue. and i'm not talking copulation type motion, i'm just talking like 1-2mm per ride. which actually is pretty significant after a ride or two to change my fit, i actually noticed the sliding with the carbon post because i was starting to get a pain behind my knee and had thought i had my fit dialed in just right! (i did, but didn't realize it was still sliding into the seat tube when i switched to carbon).

thanks again for your input.

I HATE carbon seatposts for this reason. Carbon is really ill equipped for this role. Tacx undoubtedly works, but why bother with it? There is no functional advantage to a carbon post (because, to be strong enough, it is built to be as heavy as an aluminum post).

My new frameset came with a carbon seatpost. After 25 miles, it started slipping (as I knew it would). I'm changing it out for a Thomson. I will save 40g and I will have a seatpost that I never ever have to think about.

At this point, I have to agree with you. There is no functional advantage whatsoever, as far as I can tell. The only reason I see anyone getting a carbon post is for aesthetic purposes. I've already applied the compound so I should be ok for now, however, If ever the time comes for the need of a new post... I'm going with Thompson.