My quest to solve slipping seatpost problem...

Discuss light weight issues concerning road bikes & parts.
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n808
Posts: 103
Joined: Sun Mar 16, 2014 3:09 pm
Location: Seattle, WA | Gjøvik, Norway

by n808

It should have been simple. Clean carbon frame and seatpost thoroughly. Apply carbon paste (Tacx in my case). Tighten to spec (5 Nm). Observe seatpost never slipping.

Alas, it has not been. On longer rides, after 2 hours or so, my seatpost has started slipping, slowly, just a mm at a time, so I hardly noticed it when it first occurred.

I am not sure why. Maybe because my Scott Addict R1 frame is ever so slightly oversized, closer to 31.7mm and the seatpost, Deda Superzero, a tiny bit undersized. This oversize/undersize combination causes the seatpost clamping area to become too narrow. This combined with my long legs far back seat position, and flexing carbon, has caused the slippage. I am not sure though, opinions welcome...

I tried to re-clean, and re-apply more carbon paste. I tried very thin tape to increase the seatpost diameter. No difference. I think the tape eventually got crushed and was of no use.

Now I may have figured out a solution.

First I cleaned yet again, applied a thin layer of acrylic clear nail polish to fill in scratches from the slippage and increase seatpost diameter slightly. Then I carefully sanded the nail polish layer directionally around the post, to make it less slippery. Since I am sanding only the nail polish, the carbon surface is not affected.

Finally I mixed carbon paste with some non-hardening gasket sealant (from auto shop) and applied a liberal layer of this to seatpost.

And now after several +3 hour rides, the problem appears to be solved... :beerchug: There's probably a simpler solution, carbon paste only should have worked, and does it most cases.
(2012/2014) Scott Addict R1, SRAM Red 6.6kg | 2012 Scott Scale Pro, SRAM X0, 9.4kg

rowdysluggins
Posts: 349
Joined: Tue Apr 27, 2010 2:36 am
Location: Taylosville, Utah

by rowdysluggins

That's a creative solution. Congrats! I have an R1 with a Ritchey SuperLogic seatpost and also using Tacx with no slipping. Maybe the Ritchey is a slightly larger diameter (it's also a mat UD finish).

by Weenie


kampiakseli
Posts: 80
Joined: Sun Jan 22, 2012 2:47 pm

by kampiakseli

I have used toothpaste for some years with exellent results!

Irish
Posts: 787
Joined: Mon Jul 26, 2004 8:57 pm
Location: Ireland

by Irish

I've used hairspray on the seatpost before fitting
in the past with good results.

esfrost
Posts: 84
Joined: Thu Sep 05, 2013 7:33 am
Location: Hungary/Budapest
Contact:

by esfrost

Although im only 69 kgs, and i use an aluminium seatpost (Thomson) in my carbon frame, i never had this kind of problem. I used Ritchey Liquid Torque on the seatpost. I tightened the seatpost collar (Thomson) only 2nm and the seatpost never slipped, never.

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Stolichnaya
Posts: 2621
Joined: Wed Oct 06, 2004 6:55 pm
Location: Vienna, AUT

by Stolichnaya

For a while (perhaps still) 3T was delivering carbon posts with a layer at the bottom of the post that was a gritty clear coat and that works fantastic. No slipping. Such a simple solution to a common problem. Even when I was as heavy as 90 kg, that 3T carbon post never slipped and it only had 3.5 to 4.0 Nm torque. I wonder if there is a place to purchase this clear coat with a slight grit in it. Might solve a lot of problems for a lot of people and get around those mismatched production tolerances.

n808
Posts: 103
Joined: Sun Mar 16, 2014 3:09 pm
Location: Seattle, WA | Gjøvik, Norway

by n808

Thanks for the additional tips. I might try toothpaste or hairspray next time I remove the seatpost.
Stolichnaya: my 3T-like carbon handlebar has that gritty clear coat in the clamping and brake areas. It works great.
esfrost: I am glad the simple solution works for you and it does indeed in most cases. The Enve seatpost on my Scott MTB has never slipped with nothing but Tacx carbon paste. I am 63kg.
(2012/2014) Scott Addict R1, SRAM Red 6.6kg | 2012 Scott Scale Pro, SRAM X0, 9.4kg

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BRM
Posts: 817
Joined: Sun Mar 16, 2014 3:43 pm

by BRM

Stolichnaya wrote:For a while (perhaps still) 3T was delivering carbon posts with a layer at the bottom of the post that was a gritty clear coat and that works fantastic. No slipping. Such a simple solution to a common problem. Even when I was as heavy as 90 kg, that 3T carbon post never slipped and it only had 3.5 to 4.0 Nm torque. I wonder if there is a place to purchase this clear coat with a slight grit in it. Might solve a lot of problems for a lot of people and get around those mismatched production tolerances.


- Clean the part that goes inside the seattube. Mildly with sandpaper too.
- Apply varnish with a brush ( because you dont want to have it dry too quick)
- Put fine sand over it, that will stick into the varnish.
- Let it dry and put again a layer of varnish.
- Let that dry again thoroughly.

Fine sand (in colors) for this you maybe can get in a hobbystore.
Or maybe volière (birdscage) sand.

by Weenie


ProEvoSLTeamHighMod
Posts: 65
Joined: Wed Feb 19, 2014 6:13 am

by ProEvoSLTeamHighMod

n808 wrote:It should have been simple. Clean carbon frame and seatpost thoroughly. Apply carbon paste (Tacx in my case). Tighten to spec (5 Nm). Observe seatpost never slipping.

Alas, it has not been. On longer rides, after 2 hours or so, my seatpost has started slipping, slowly, just a mm at a time, so I hardly noticed it when it first occurred.

I am not sure why. Maybe because my Scott Addict R1 frame is ever so slightly oversized, closer to 31.7mm and the seatpost, Deda Superzero, a tiny bit undersized. This oversize/undersize combination causes the seatpost clamping area to become too narrow. This combined with my long legs far back seat position, and flexing carbon, has caused the slippage. I am not sure though, opinions welcome...

I tried to re-clean, and re-apply more carbon paste. I tried very thin tape to increase the seatpost diameter. No difference. I think the tape eventually got crushed and was of no use.

Now I may have figured out a solution.

First I cleaned yet again, applied a thin layer of acrylic clear nail polish to fill in scratches from the slippage and increase seatpost diameter slightly. Then I carefully sanded the nail polish layer directionally around the post, to make it less slippery. Since I am sanding only the nail polish, the carbon surface is not affected.

Finally I mixed carbon paste with some non-hardening gasket sealant (from auto shop) and applied a liberal layer of this to seatpost.

And now after several +3 hour rides, the problem appears to be solved... :beerchug: There's probably a simpler solution, carbon paste only should have worked, and does it most cases.


A simpler solution might be to try removing the clamp bolt, greasing it, and then re-installing it. It's amazing what 5Nm is on a greased bolt (which is how it should be) vs a dry or dirty bolt (3Nm? 4Nm? hmm?) - proper torque, as in with a greased bolt, with carbon paste is generally an excellent solution.

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