# Seatpost won't stop slipping!



## Scart (Sep 18, 2009)

I'm a big boy (6'3" 230#), so I know that has something to do with it. But I can't complete a loop of my local trail without having to stop at least once to adjust my seat post height. Riding a Stumpy FSR 120 with a Specialized seat post, and it's the right size. I've tried it with a tiny amount of grease on the post, completely dry, cleaned to within an inch of its life... to no avail. I obviously don't want to put any sort of semi-permanent adhesive in there, but it's making me nuts.. 

Anyone have suggestions as to how to make it stick?


----------



## reptilezs (Aug 20, 2007)

carbon grit paste. turn collar around


----------



## nov0798 (Nov 27, 2005)

rough it up with sandpaper so it has something to grip on to. If you have someone who has a lathe, you can knurl the bottom to the point where you like it. This will give it something to grab on to, and let you know instantly the height you like it at.


----------



## Ratt (Dec 22, 2003)

Scart said:


> I'm a big boy (6'3" 230#), so I know that has something to do with it. But I can't complete a loop of my local trail without having to stop at least once to adjust my seat post height. Riding a Stumpy FSR 120 with a Specialized seat post, and it's the right size. I've tried it with a tiny amount of grease on the post, completely dry, cleaned to within an inch of its life... to no avail. I obviously don't want to put any sort of semi-permanent adhesive in there, but it's making me nuts..
> 
> Anyone have suggestions as to how to make it stick?


Change to a bolt-on clamp from a quick release one and grease the bolt threads. Or get a quick release clamp without a plastic wedge that will compress and slip, i think Hope uses a brass cam. And then there is the grease her up and get her dirty with good ole dirt method too.


----------



## thickfog (Oct 29, 2010)

I have read chalk sans any grease works wonders. 

I had carbon paste laying around and used it. No slip so far about 70 some miles.


----------



## kuykendallc (May 30, 2011)

thickfog said:


> I have read chalk sans any grease works wonders.


I am 270 and this is the only thing that works for me.


----------



## eric1115 (Jul 8, 2008)

Carbon assembly paste. If you've got QR, replace it with a bolt collar.


----------



## RSWMTB (Jun 7, 2011)

You may want to look at a beefy collar, like a Salsa 'lip lock' etc...they have a wider profile than most, thus they grip hard along more surface area.


S


----------



## Mr.Magura (Aug 11, 2010)

eric1115 said:


> Carbon assembly paste. If you've got QR, replace it with a bolt collar.


Carbon assembly paste is a very bad solution for a slipping seat post.

Carbon assembly paste, is actually the same as grinding compound, so if used in a place where it's not going to be clamped down once and for all, it will......yes you guessed it, it will grind. 
For bar / stem, stem / steerer tube interfaces, it may be fine to use, but that's it.

Chalk without grease will do the trick. A bolt collar is also a step on the way. You can even have double bolt collars, which seems to sort the problem to some extend.

Magura


----------



## gardcol (Jan 16, 2011)

*Reverb*

Get a rockshox reverb and a clamp. Torque to 5"lbs and it will never slip but allow you to adjust up and down on the fly. I love it !!


----------



## bad mechanic (Jun 21, 2006)

Verify with calipers the seat post and seat tube are the correct size. There are also tolerances in seat post sizing, which can lead to a looser than normal fit.

If it fits, you can also try this:
Universal Cycles -- PS Double Clamps


----------



## eric1115 (Jul 8, 2008)

Mr.Magura said:


> Carbon assembly paste is a very bad solution for a slipping seat post.
> 
> Carbon assembly paste, is actually the same as grinding compound, so if used in a place where it's not going to be clamped down once and for all, it will......yes you guessed it, it will grind.
> For bar / stem, stem / steerer tube interfaces, it may be fine to use, but that's it.
> ...


The "grit" in Tacx carbon assembly paste is actually tiny plastic beads. I've used it for years on dozens if not hundreds of carbon posts (especially in carbon frames) with no ill effects. I've seen MANY more posts come in ruined due to galvanic corrosion (yes, carbon posts) or overtightening a collar because there wasn't enough friction to keep the post from slipping than from "grinding."

I can't say whether chalk prevents corrosion, but part of the benefit to carbon paste is that it provides an insulating layer (like grease on an aluminum post) to keep the post from bonding to the frame. Cervelo recommends it (on seatposts as well as other places), as do many other manufacturers who know their stuff when it comes to carbon.

I'm sure you have had good results with chalk, but I think it's incorrect to say assembly paste is a bad solution.

-Eric


----------



## Mr.Magura (Aug 11, 2010)

eric1115 said:


> The "grit" in Tacx carbon assembly paste is actually tiny plastic beads. I've used it for years on dozens if not hundreds of carbon posts (especially in carbon frames) with no ill effects. I've seen MANY more posts come in ruined due to galvanic corrosion (yes, carbon posts) or overtightening a collar because there wasn't enough friction to keep the post from slipping than from "grinding."
> 
> I can't say whether chalk prevents corrosion, but part of the benefit to carbon paste is that it provides an insulating layer (like grease on an aluminum post) to keep the post from bonding to the frame. Cervelo recommends it (on seatposts as well as other places), as do many other manufacturers who know their stuff when it comes to carbon.
> 
> ...


Ok, I wasn't aware that the one Tacx makes is based on polymer beads. 
The one I know is a no-no is the one from Finish-Line. It eats just about anything in the long run. They even list it in their data sheet as an abrasive filler:madman:

Magura


----------



## PissedOffCil (Oct 18, 2007)

Mr.Magura said:


> Carbon assembly paste is a very bad solution for a slipping seat post.
> 
> Carbon assembly paste, is actually the same as grinding compound, so if used in a place where it's not going to be clamped down once and for all, it will......yes you guessed it, it will grind.


How often do you move your post around???


----------



## Mr.Magura (Aug 11, 2010)

PissedOffCil said:


> How often do you move your post around???


On some bikes, a couple of times each ride. 
For other bikes once a year, just to check it's not stuck.

Especially my DH/AM bike would be in the "a couple of times each ride" category.
I see others do the same, or use a drop post.

Magura


----------



## NYrr496 (Sep 10, 2008)

I am also a big boy and I also ride a Stumpjumper. I swapped out the seatpost for a Thomson and the clamp for Syntace. Cured it for me.


----------



## iridetitus (Sep 16, 2004)

chalk as in.......chalk? school house blackboard chalk?


----------



## thickfog (Oct 29, 2010)

Like chalk for climbing and weight lifting. More convenient than using little sticks of chalk!


----------



## PissedOffCil (Oct 18, 2007)

Mr.Magura said:


> On some bikes, a couple of times each ride.
> For other bikes once a year, just to check it's not stuck.
> 
> Especially my DH/AM bike would be in the "a couple of times each ride" category.
> ...


I see. Haven't done that in a while, I just find a happy medium.
Myy GF had a slipping post a couple fo weeks ago and I used Finish Lien carbon paste and it worked. Given we move the post a couple times a year I doubt it's a problem.


----------



## Mr.Magura (Aug 11, 2010)

PissedOffCil said:


> I see. Haven't done that in a while, I just find a happy medium.
> Myy GF had a slipping post a couple fo weeks ago and I used Finish Lien carbon paste and it worked. Given we move the post a couple times a year I doubt it's a problem.


To be honest, I have no definite time line as to how long it takes to get wear issues with the Finish-Line Carbon paste, so I can't say if it's gonna work out or not.

I would though ditch the Finish-Line paste in favor of the Tacx version, as that seems less risky.

Also if it's a solution to a seat post / seat tube being out of tolerance, I guess there is not much to loose, no?

My concern would be like for instance my DJ / trials bike is a steel frame, and I made a carbon seat post for it. Now that configuration would go bad real quick with some abrasive in the mix.

Magura


----------



## jeffscott (May 10, 2006)

Scart said:


> I'm a big boy (6'3" 230#), so I know that has something to do with it. But I can't complete a loop of my local trail without having to stop at least once to adjust my seat post height. Riding a Stumpy FSR 120 with a Specialized seat post, and it's the right size. I've tried it with a tiny amount of grease on the post, completely dry, cleaned to within an inch of its life... to no avail. I obviously don't want to put any sort of semi-permanent adhesive in there, but it's making me nuts..
> 
> Anyone have suggestions as to how to make it stick?


Believe it or not....clean and grease the seat tube and post...

Then clean and grease the saddle quick release....

Insert and clamp up has hard as you can...

Works for me.

Oh yeah about 2 years ago Specialized was making some really shitty seat clamps...

So if it is 2 to 5 years old you might just need a better seat clamp.


----------



## zebrahum (Jun 29, 2005)

I have one of these on every QR seatclamp bike I have and it removes all slip from any bike I've used it on:
Salsa Cycles | Components

And whenever I suggest that clamp, many other people suggest this one as even stronger:
Seat QR - Chromag Bikes

With a good clamp you should be able to run your post with the standard thin layer of grease and have no issue trying to mix and match lubrication solutions.


----------



## eric1115 (Jul 8, 2008)

I think there is some clarification that should happen here:

Aluminum post: I always use grease (grease the frame, not the post so it doesn't get scraped off). You could use carbon assembly paste instead if you want. I also don't worry about overtightening so much. Never had an issue with any of my or my customers' bikes (other than lack of grease leading to galvanic corrosion).

Carbon post: NEVER use grease. It'll make an already slippery carbon seatpost impossible to keep from slipping without going super tight on the clamp. Since carbon doesn't resist crush loads as well as aluminum, it goes snap, crackle, pop. I've seen this MANY times with people who grease (or leave dry) their carbon posts. Use carbon assembly paste, as it increases the friction between post and frame, reducing the clamping force needed to keep from slipping, protecting the seatpost from those crushing forces.


----------



## TronTronTron (Mar 31, 2011)

A shaft collar placed at the position you like your seat is an easy solution. It will prevent the post from creeping and it will also make it easy for perfect seat positioning in the future.


----------



## Econoline (Mar 5, 2004)

I've had a few slipping seat posts, and all were Thompson and slightly under spec. Thompson will exchange, but I ended up going to Ritchey and end of problem.


----------



## Scottie Rox (Jul 1, 2003)

Sorry to dig up an old thread...
Im in a bad way with my seat post clamp too.
broke the ori 30.8 mm over tighten (Local spech cant find any)
kcnc 31.8 was too loose broke it over tighten
kcnc 30.7 fit great it broke under heavy use didn't even realise till the next day
got a no name 31.8 qr thats pretty strong h and holds ok for a while so the LBS put carbon paste in it now it creaks like crazy...
alloy frame and post stumpjumper


----------



## Shark (Feb 4, 2006)

Scottie Rox said:


> Sorry to dig up an old thread...
> Im in a bad way with my seat post clamp too.
> broke the ori 30.8 mm over tighten (Local spech cant find any)
> kcnc 31.8 was too loose broke it over tighten
> ...


Have you tried a new seat post?


----------



## BADDANDY (Feb 20, 2012)

I fixed my slipping seatpost, knurling with a punch and hammer.


----------

