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Old 12-30-10, 08:56 AM   #1
Fast505
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Carbon Seatpost in Steel Frame

I have an Easton carbon seatpost in a steel IF frame. I've noticed a slight amount of rust developing inside the seat tube where the seatpost clamps. I do not use grease with carbon. Would a special compound like the Tacx paste also prevent rust? Is it OK to lightly coat the clamp area with JP Weigle's?
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Old 12-30-10, 09:10 AM   #2
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?? Am I missing something here. My CF post is greased and has been in a steel framed bike since August. Are we not supposed to use grease on CF? Seems that would be a problems since the bearings on my CF Madone 5.9 are pressed into the CF. Just curious...
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Old 12-30-10, 09:46 AM   #3
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Yes, you're not supposed to grease carbon seatposts, for two reasons: possible chemical interaction that breaks down the carbon (sounds unlikely and probably could still find a type of grease that didn't have this issue) and because if you make a carbon seatpost slippery with grease, you'll likely need to exceed the torque limit (5nm?) of the seatpost in order to keep it in place.

I bought a slightly used Ritchey steel frame and it came with a nice ritchey wcs carbon seatpost. For the first reasons above, I was hesitant to spray frame saver down my seat tube. The specifications for the carbon seatpost talk about being sure to completely clean the seat tube of any grease and whatnot before installing it. I was also hesitant to use the seatpost dry because as this is a travel bike, it'd need to be removed and replaced many times and I didn't want to damage the seatpost by sliding it in and out without grease. I mean, it was pretty damn hard to get out the first time.

In the end I just decided to swap it out to the aluminum wcs seatpost just in case. (matches my stem and bars better anyway since they are also wcs aluminum). The weight of the aluminum seatpost was very close to the carbon one and I doubt I notice any difference in stiffness/comfort/fashion.
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Old 12-30-10, 11:13 AM   #4
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All carbon assembly should be done with carbon assembly paste - this reduces the chance that

a) It will slip
b) reduces necessary torque on securing parts/fastener to get it to stay put - bigger safety margin
c) prevents the post from seizing - this is very bad

Mainly, used for seatpost installations and occastionally handlebar/stem combos and lever/bar combos. When any or both are carbon.
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Old 12-30-10, 11:14 AM   #5
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Quote:
Originally Posted by jamesdak View Post
?? Am I missing something here. My CF post is greased and has been in a steel framed bike since August. Are we not supposed to use grease on CF? Seems that would be a problems since the bearings on my CF Madone 5.9 are pressed into the CF. Just curious...
Yes you are, in fact the bearings pressed into your CF frame have installation instructions that state *explicitly* to grease the carbon seats in the bottom bracket shell. This is *completely* different from a seatpost where there is a risk of slippage, same goes for stem/bar and stem/steerer interfaces. The latter two very rarely needing assembly compound.

Quote:
Originally Posted by pacificaslim View Post
I bought a slightly used Ritchey steel frame and it came with a nice ritchey wcs carbon seatpost. For the first reasons above, I was hesitant to spray frame saver down my seat tube. The specifications for the carbon seatpost talk about being sure to completely clean the seat tube of any grease and whatnot before installing it. I was also hesitant to use the seatpost dry because as this is a travel bike, it'd need to be removed and replaced many times and I didn't want to damage the seatpost by sliding it in and out without grease. I mean, it was pretty damn hard to get out the first time.
Your fear is unfounded, there are many bikes out there with carbon posts in steel/al/carbon frames. Standard practice, again is to use carbon assembly paste.
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Old 12-30-10, 12:07 PM   #6
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Hmm, maybe I should pull the seatpost and check it out. Then again, it has not slipped in over a 1000 miles so why worry. I've got spare posts if needed and I can't see it getting stuck if it's greased.
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