# I’ve got the Slipping Seatpost Blues



## Paul1PA (Sep 16, 2006)

Recently finished my first “frame up” custom build. Absolutely love the bike except for one issue: The seatpost keeps slipping down inside the seat tube. Frame is an ’07 LeMond Poprad made from True Temper OX Platinum steel. The seatpost is an aluminum Thomson Elite. The clamp itself is a chrome Bontrager model that came with the frameset.
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Trek/LeMond states the seatpost O.D. should fall within 27.12 – 27.20 mm. Using dial calipers, my Elite measures exactly 27.20 mm (typical Thomson precision!). Haven’t checked the I.D. of the frame yet, but there is almost no detectable slop when inserting the seatpost – seems like a perfect sliding fit.
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Each time I reset the seatpost height, I’ve progressively torqued the binder bolt a bit more. Even at a whopping 125 in-lb, the seatpost will still head south. And yes, there is plenty of gap left in both the frame’s key hole slot and clamp so they’re not bottoming out.
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Granted, I’m a few double cheeseburgers away from being a <st1>Clyde</st1> (195 lbs) and ride on some pretty rough roads. But still, my MTB hardtail sees much worse abuse and never slips. Oh yeah, as standard procedure, I did grease the seatpost with Park Polylube. 
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At this point, I’m rather perplexed! One solution is to add a second clamp directly on the seatpost. This would then rest against the upper lip of the stock chrome clamp. Together, the pair of clamps should easily solve the problem I suspect. 
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Does anyone make a clamp with a size 27.2 mm I.D.? If not, I was thinking of getting a seatpost shim and cutting it down to the height of the second clamp (see photo below). I know there are some real experts here, so any other easier remedies would be much appreciated as well (like maybe knurling the seatpost, using a special grease, etc.) 
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TIA,
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Paul


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## azoomm (Oct 19, 2007)

Just get a new seat post clamp and see how that works. Since you're not running a carbon post, you can clamp the sh!t out of it, and something like the Salsa, with it nice, big bolt will do the trick nicely. You're going to crush a post before crushing the seat tube, but that's pretty much a non-zero chance with the Thomson.


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## rogerstg (Aug 1, 2007)

Tighten it more - until it does not slip.


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## cyclust (Sep 8, 2004)

It must be a problem with the seatpost clamp. The ribs of the thomson post make it the most slip resitant post on the market.


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## terry b (Jan 29, 2004)

Coat the bottom of the post with pump hairspray, up to the point where it's exposed. Let sit for 10 seconds, put it in and torque to recommended settings.

I've had posts that slip no matter how tight they are set, hair spray fixes all.


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## azoomm (Oct 19, 2007)

Wait... I thought duct tape fixes all. Maybe hair spray is the bizarro duct tape.

Either way, apply more force.


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## anthony.delorenzo (May 8, 2007)

If you don't mange to get it sorted, I would recommended trying a Surly seatpost clamp.


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## djg21 (Oct 25, 2003)

Buy another seat collar and use some Tacx or Ritchey carbon assembly paste rather than grease on the post.


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## Eric_H (Feb 5, 2004)

*Try some "Carbon Assembly Paste"*

I would suggest trying some of the so-called carbon assembly paste. This stuff is basically a gelatin-like goop with little plastic spheres embedded in it. Kind of like liquid sandpaper. The plastic spheres compress and increase the friction between the seatpost and seat tube.

It is sold by Tacx - Carbon Assembly Paste, Ritchey - Liquid Torque, and FSA also calls it something else. I think it is all teh same stuff. Ritchey claims a 30% reduction in torque to achieve the same level of fastening, so in your case it it should be a 30% increase in holding power.


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## terry b (Jan 29, 2004)

azoomm said:


> Wait... I thought duct tape fixes all. Maybe hair spray is the bizarro duct tape.
> 
> Either way, apply more force.


The three Prime Items to fix everything are duct tape, baling wire and galvanized drywall screws.

Pump hairspray is the 4th.


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## Dinosaur (Jan 29, 2004)

Make a shim out of a pop or beer can. Cut it to 1x4 inches, round out the corners. You might have to experiment with the size. Put a light coat of grease on both sides of the shim. The trick is to get it to go down the seat tube with the seat post without it falling all the way down, or having some of the shim sticking out on top. I had this very same problem with Thomson seat posts. I stopped using them as they don't have enough setback, even with the setback model.

I learned this from an article by Lennard Zinn. If you drink pop or beer it won't cost you a cent. Worth a try.

Or buy a different seatpost. I use an Alpha Q carbon and I have to use a little force to get it down.

AH- I now see that you are using a shim. Since you don't have a carbon bike or seatpost, just clamp the cra* out of it.


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## Dave Hickey (Jan 27, 2002)

What Terry said...Buy the extra-mega hold hairspray....The kind of stuff that a honkytonk angel wears on Saturday night....

Seriously, it works......try it...


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## azoomm (Oct 19, 2007)

terry b said:


> The three Prime Items to fix everything are duct tape, baling wire and galvanized drywall screws.
> 
> Pump hairspray is the 4th.


Why would you use galvanized drywall screws? They are used in interior applications and go into either wood or light gauge metal studs... what benefit does the galvanization do?

Oh... I see... it's because of that which makes it magical. Got it :thumbsup:


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## dhtucker4 (Jul 7, 2004)

The problem with a Salsa seatpost clamp is that you have to crank it hard - you should try a good Y-allen wrench (3, 4, 5 mm), so you can torque the bejessus out of your seatpost and your seat tube AND your seatpost clamp. 

You ought to call Thompson and Lemond (made by Trek) and see what the deal is. I had a decent aluminum seatpost slip (Ritchey WCS), but it was the clamp - the bolt in the clamp was stripped. It took a lot of elbow grease to get the old clamp off and to get the new clamp on - I finally used a rubber mallet (Reynolds 853 seat tube).


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## Dr. Placebo (May 8, 2007)

> The rattling cobblestones notoriously take their toll on forks, seatposts and bottle cages, and Slipstream has a few tricks up its sleeve. Two weeks ago the camp held a two-day “Cobble Camp” on Roubaix’s sectors, and found that the constant jarring was causing seatpost slippage. *To combat this, the mechanics have affixed metal hose clamps — the same you might purchase at a hardware store — to the base of each riders’ seatpost.*
> 
> “We have them right at the collar. Yeah, it’s a pretty stock piece, but that post isn’t going to slip at all,” Hopper said.


link for pics


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## terry b (Jan 29, 2004)

azoomm said:


> Why would you use galvanized drywall screws? They are used in interior applications and go into either wood or light gauge metal studs... what benefit does the galvanization do?
> 
> Oh... I see... it's because of that which makes it magical. Got it :thumbsup:


They don't rust, so if the thing you repaired with them ends up at the bottom of the sea, it will stay repaired.


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## Mersault (Jan 3, 2005)

*zip ties*



terry b said:


> The three Prime Items to fix everything are duct tape, baling wire and galvanized drywall screws.
> 
> Pump hairspray is the 4th.


and zip ties, all hail the mighty zip ties :biggrin5:


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## BikeGeek (Mar 19, 2005)

Take some of the grease off untill it is just a very light coating. Also make sure the bolt and bolt head are greased so you are getting and accurate torque value and not just bolt head friction. Greasing the inside of the seat collar also can help allowing it to slide on the paint as is is clamped down. 

If all else fails reef the crap out of it.


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## ddakin (Jun 2, 2004)

*Seat post slipping solution?*

I'm researching the market for a seat post lock ring. Basically it would sit above the seat post clamp to keep carbon seat posts from slipping back into the frame. It would be extremely light (approx. 8 grams), but would serve the purpose as needed. They might also be convenient for people who have to remove their seat post for travel purposes. It would be an easy way to 'set' the height of your seat. 

I realize that there are pastes and such out there now, but my question is do you think there's a market for this type of clamp solution?

It would be available in 27.2 and 31.6mm sizes.

Your thoughts?

Dan Dakin
www.chasebicycleproducts.com


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## rogerstg (Aug 1, 2007)

ddakin said:


> I'm researching the market for a seat post lock ring. Basically it would sit above the seat post clamp to keep carbon seat posts from slipping back into the frame


I think that you've just described a hose clamp


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## anthony.delorenzo (May 8, 2007)

ddakin said:


> I'm researching the market for a seat post lock ring. Basically it would sit above the seat post clamp to keep carbon seat posts from slipping back into the frame. It would be extremely light (approx. 8 grams), but would serve the purpose as needed. They might also be convenient for people who have to remove their seat post for travel purposes. It would be an easy way to 'set' the height of your seat.
> 
> I realize that there are pastes and such out there now, but my question is do you think there's a market for this type of clamp solution?


Scroll up to post #15 on this thread for a link to just such a device, as used in the Tour de France: A common hose clamp. 

Regards, 
Anthony


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## Paul1PA (Sep 16, 2006)

As the OP of this thread, I appreciate all the helpful responses! At this point, I think the clamp itself is just "weak sauce". As 'cyclust' pointed out, Thomson purposely leaves small machining grooves on their posts for better grip. The seat tube was reamed properly too.

I've heard of Tacx carbon assembly paste. However, wasn't aware it would work on metal applications too. The "honkytonk angel" hairspray may be worth a try as well!  My only concern is if these methods will still offer corrosion protection (???). One thing worse than a slipping seatpost is a seized one! 



ddakin said:


> I'm researching the market for a seat post lock ring. Basically it would sit above the seat post clamp to keep carbon seat posts from slipping back into the frame. It would be extremely light (approx. 8 grams), but would serve the purpose as needed. They might also be convenient for people who have to remove their seat post for travel purposes. It would be an easy way to 'set' the height of your seat.
> 
> I realize that there are pastes and such out there now, but my question is do you think there's a market for this type of clamp solution?
> 
> ...


Yep Dan, you described exactly what I was looking for! Definitely a more elegant solution than a hose clamp. And you're correct, it could be a very minimalistic design since the primary clamp will still provide the bulk of the holding power. Send me a prototype - size 27.2 please! :thumbsup:

Paul


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## cmg (Oct 27, 2004)

turn the clamp 180* where the clamp bolts are over the top tube. torque as before, this may provide a more uniform force. with the clamp bolt and the seat post slot aligned the clamp really only closes down the slot and may not have as uniformed closure. the other way there is very little pressure on the slot but as the diameter gets squeezed it will have to reduce. give it a try.


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## smokey422 (Feb 22, 2004)

Try valve lapping compound, you can get it at any auto parts store. I'm a clyde and I successfully used it to fix a slipping post on my mountain bike.


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## Stogaguy (Feb 11, 2006)

*After Hairspray, Grease or not?*

Do you still grease on top of the hairspray? If no, is seizing the post in the frame an issue?

I have the same issue with my Poprad, just not to the same degree as the OP. My post is an FSA SL-220.


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## albert owen (Jul 7, 2008)

terry b said:


> The FOUR Prime Items to fix everything are *WD40*, duct tape, baling wire and galvanized drywall screws.
> 
> Pump hairspray is the 5th.


Fixed


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## gnatman (Jan 14, 2009)

You and make a shim from aluminum oxide wet-dry sandpaper. Very fine grit, like 1200 or 1500. It's usually black. Get it at auto parts stores. Make the shim same as the beer can shim described in an earlier post. Put the sandpaper side facing in. Use probably just one wrap.


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## pmt (Aug 4, 2009)

Eric_H said:


> I would suggest trying some of the so-called carbon assembly paste. This stuff is basically a gelatin-like goop with little plastic spheres embedded in it. Kind of like liquid sandpaper. The plastic spheres compress and increase the friction between the seatpost and seat tube.
> 
> It is sold by Tacx - Carbon Assembly Paste, Ritchey - Liquid Torque, and FSA also calls it something else. I think it is all teh same stuff. Ritchey claims a 30% reduction in torque to achieve the same level of fastening, so in your case it it should be a 30% increase in holding power.


This is the correct answer.


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## pgk (Jun 30, 2008)

Anti Seize is what you need.


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## TiCoyote (Jun 28, 2005)

Clean your seatpost really well with alcohol, or something that dries with no residue. Do the same with the inside of the frame. Then rub chalk on the seatpost.


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## jrlombard (Sep 9, 2009)

BikeGeek said:


> Take some of the grease off untill it is just a very light coating. Also make sure the bolt and bolt head are greased so you are getting and accurate torque value and not just bolt head friction. Greasing the inside of the seat collar also can help allowing it to slide on the paint as is is clamped down.
> 
> If all else fails reef the crap out of it.


Thank you. I was reading down the threads waiting for someone to suggest greasing the bolt and head to ensure an accurate torque.

+1 for those who suggested hairspray, and another +1 for the carbon assembly paste like Tacx.


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## CleavesF (Dec 31, 2007)

You guys know that Thomson themselves say that you should NOT use shims with their seatposts right?

I'm not even joking here.


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## wankski (Jul 24, 2005)

absolutely do not overtighten!

u do not need to grease, this is probably your issue... the thomson has a coating so it will not sieze... use a torquing compound if you feel necessary...

http://cozybeehive.blogspot.com/2009/04/broken-thomson-seatposts-overtightening.html


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## Paul1PA (Sep 16, 2006)

I ultimately ended up using this Lock Ring made by Chase and readily available on eBay:

http://www.chasebicycleproducts.com/

This is a minimalistic clamp that mounts directly onto your seatpost w/o shims (comes in either 27.2 or 31.6 mm sizes). Only weighs ~6 grams and immediately solved my slipping issues. 

Oh yeah, this Lock Ring has two other advantages: For one, it serves as a handy height index when removing my seatpost for travel or maintenance. And second, I feel more secure when riding knowing such a critical component is held in place with two bolts instead of just one.

Below is a pic of the 27.2 size mounted on my LeMond Poprad (it's the tiny black clamp mounted directly above the OEM chrome seat collar). Disclaimer: I'm not affiliated with Chase, just a satisfied consumer.

Hope this helps! :thumbsup:

-Paul


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## frdfandc (Nov 27, 2007)

If the bike in question is steel or aluminum, use a light coating of grease on the post. Even a Thompson. I had a Thompson Elite setback post on a customers bike was seized in a steel frame.


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## MrPolak (Aug 25, 2021)

Old post, but for the sake of an answer to the internal diameter of the Platinum OX Lemond Poprad seat tube, I measured 27.4. My 27.2 seat post was also slipping until I shimmed it with a cut aluminium pop (soda, coke, Pepsi) can. Can's wall thickness is stated as 0.097, so the math adds up.


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## Lombard (May 8, 2014)

MrPolak said:


> Old post, but for the sake of an answer to the internal diameter of the Platinum OX Lemond Poprad seat tube, I measured 27.4. My 27.2 seat post was also slipping until I shimmed it with a cut aluminium pop (soda, coke, Pepsi) can. Can's wall thickness is stated as 0.097, so the math adds up.


Interesting way of making a shim.


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## tlg (May 11, 2011)

Lombard said:


> Interesting way of making a shim.


That hack has been around for decades. 









Have a brew, fix your bike


No this is not about beer, it's about shims.. http://www.insidetri.com/train/bike/articles/1304.0.html Lennard Zinn article about making shims from beer or pop cans for slipping seatposts. Cheap fix and it works.... Just make sure you don't drink too many beers before you try this.




www.roadbikereview.com




Jan 27, 2005
No this is not about beer, it's about shims..


http://www.insidetri.com/train/bike/articles/1304.0.html


Lennard Zinn article about making shims from beer or pop cans for slipping seatposts. Cheap fix and it works....
Just make sure you don't drink too many beers before you try this.









long term DIY seatpost shims??


I recently purchased a post/shim on ebay and found out that the ebay ad was not correct....it said that the post was 26.6 w/ a shim for 27.2...I couldn't fit the post in my KM. I'd like to use the post in my KM, but don't want to damage the frame. I've used aluminum cans in the past, but is...




www.mtbr.com


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