Well, like anything, not all frames and not all seatposts are created equal.

What one company considers to be 27.2 mm may be significantly different than a given seatpost manufacturer's interpretation of 27.2 mm.

There are some brands of frames that are notorious for not gripping posts. That is an annoyance.

While this doesn't do you much good with your U.S.E. post, which is a very fine post by the way, the Easton post which I am using on my Guru Cron-Alu has a relieved flat section that enables greater clamping force at the seat post binder area. It seems to work OK, never any problems.

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Tom Demerly
The Tri Shop.com

Hairspray worked for me. Raid your wifes toiletry bag ?

Make sure you are NOT applying any grease to your post. Carbon posts generally should NOT be greased.

Also, have you measured your seat tube diameter and seat tube diameter to make sure they are both the same size. I've had people bring in their bikes only to tell them they have a 27.0 when they should have had a 27.2. Measure them to confirm.

If they are correct, you can also try a larger seat clamp and as a last resort, simply sell the post and go back to an alum post.

I can second the hair spray solution... it has worked everytime for me.

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I agree with Tom, you can also try turning the clamp around half a turn. Some frames tighten better with the clamp bolt opposite to the slot in the seat post tube....

now I have the same problem with a decent quality round carbon post in a new aluminum frame (no grease of any kind and I checked all the measurements). it creeps down very slightly with minimal road bumps.

can you give me any more details of this clever hairspray solution? spray from a hand pump container will work fine? should I let it dry completely? stick it on just the post? or inside the seat tube too? any other tips?

Thanks.

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Where would you want to swim ?

if you can also give me any tips as to how to this best (see post above), it would be highly appreciated.

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Where would you want to swim ?

Just take the post out and spray it liberally (probably best to spray away from your beautiful machine) then just slide it into the frame and tighten at the right height. The spray sets sticky and provide just enough grip.

I'd leave it to set for an hour or more though - just to be safe.

Thanks.

A strange question: if I change saddles later and need to adjust the seat height by a few mm, do you think I'll have problems later gettin the damn thing to move? and then getting the post to stay in the new position?

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Where would you want to swim ?

Shouldn't be a problem - its not that sticky.

I found the best way to brake the bond that the hair spray creates is to simply hit the nose of the saddle sideways with the palm of your hand. One swift hit seems to do it just fine.

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Thanks for all the input. I ask these questions because this is on a bike where I am still (slightly) fine tuning my position.

So, if I break the hairspray bond (easy to do) and then readjust the saddle ht. a little, do you think I should re-coat with more fresh hairspray, or will the old dried stuff still do the trick of keeping the post from sliding when I re-tighten the collar?

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Where would you want to swim ?

You are going to have to re-coat the post. Once it dries it is no longer sticky.

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