# seatpost clamp torque?



## DaveG (Feb 4, 2004)

I picked up a monocoque carbon frame. It uses an aluminum seatpost clamp that uses two bolts. I've been living in the world of steel bikes where I just torque a single bolt to 50 inch.lbs and nothing bad happens. What should be the torque on each bolt? Any other things I should know about? I am using a 31.6 carbon post also.


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## Camilo (Jun 23, 2007)

I don't know about your bike adn post, but my Bontrager carbon post has a torque spec. I'm ot aware of a spec for my frame or binder, so I just use the post spec.


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## The The (Sep 9, 2002)

The clamp on my carbon frame says 5Nm (44 inch pounds). I would say this is a fairly standard rating for these parts.


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## wim (Feb 28, 2005)

*Careful.*



Camilo said:


> I don't know about your bike adn post, but my Bontrager carbon post has a torque spec. I'm ot aware of a spec for my frame or binder, so I just use the post spec.



Torque specifications are for screws, so the only torque specs a seatpost can possibly have are those for the saddle rail clamp tightening screws. As a rule, these are much higher than the seat post clamp tightening screw, which, as said, is generally about 5 Nm.


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## Camilo (Jun 23, 2007)

wim said:


> Torque specifications are for screws, so the only torque specs a seatpost can possibly have are those for the saddle rail clamp tightening screws. As a rule, these are much higher than the seat post clamp tightening screw, which, as said, is generally about 5 Nm.


This is normally true, but as I mentioned above my carbon seat post (Bontrager) does have a torque spec for the seat post clamp (in other words, it is not the bolt that has the spec, it is the post) and also has a torque spec for the rail bolts. I have no idea if it is the same of different than what what is or would be spec'd by the seat post clamp manufacturer since I've never seen such a torque spec for mine.

Here is an excerpt from the owner's manual for my seatpost:

Tighten the following bolts:
• Seat post binder: 85-125 lb•in (9.6-14.1 Nm),
or 65-80 lb•in (7.3-9 Nm) for a carbon fiber seatpost.
• Seat fixing bolt: 100-150 lb•in (11.3-17.0 Nm).

Note that the seat post binder spec is different for carbon post, therefore not based on the bolt, but the post itself.

Also, I recently changed from aluminum handlebars and a fork with aluminum steer tube to carbon handlebars and a fork w/ carbon steer tube. I can't remember which, but one of those components stated a maximum torque spec. I think it was slightly smaller than the bolt spec printed on the stem. I used carbon paste so it wasn't a problem.


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## wim (Feb 28, 2005)

Camilo said:


> Here is an excerpt from the owner's manual for my seatpost:
> 
> Tighten the following bolts:
> • Seat post binder: 85-125 lb•in (9.6-14.1 Nm),
> ...


Interesting, thanks for posting. I'm surprised that Bontrager did this, and did this without mentioning the size of the binder bolt. IMO, it's a bit going out on a limb—then again, most binder bolts are the same size, so not that big a deal.


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## Dinosaur (Jan 29, 2004)

I had a Bontrager Race XXX carbon seatpost. Never paid attention to the torque specs. No problem. In all my years of riding I have only damaged one frame by over tightening the seat post clamp bolt and that was on a Viscount. They were notorious for doing that. I have snapped a few binder bolts by constantly messing with them. Just tighten by feel and ride, Check to make sure your seat post is not slipping. You can break anything if you over-tighten it.


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## XR4Ti (Jul 8, 2008)

Consider using a carbon paste.


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## DaveG (Feb 4, 2004)

*what do you recomend?*



XR4Ti said:


> Consider using a carbon paste.


I am aware that Ritchey and FSA make some sort of sticky paste for that purpose. I have never tried either. What would you recomnend?


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## XR4Ti (Jul 8, 2008)

DaveG said:


> I am aware that Ritchey and FSA make some sort of sticky paste for that purpose. I have never tried either. What would you recomnend?


Can't recommend one over the other as I have only used this one, but I tried Fiber Grip by Finish Line and it worked well. It's not sticky but feels gritty to add friction. It does not scratch.


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