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Discussion Starter · #1 · (Edited)
I have a Campy record carbon seatpost, which I am putting in a carbon frame. The carbon frame has an aluminum sleeve built into it. The post is damaged from the cleft of the aluminum sleeve digging into it. Structurally, I think it's OK, it's a pretty thick post.

My question is, since the carbon seatpost has been damaged and the carbon exposed, will greasing it still keep it from galvanic corrosion with the aluminum? Here's a photo of the damage:

Trouble is, even if I bought a new one, the fit is EXTREMELY tight. It would probably damage the new one too.
 

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I think it's probably cosmetic. However, NEVER grease a carbon seatpost. You'll wind up riding on the top tube after you hit your first bump.

Also, because the seatpost is carbon fiber, you don't need to worry about galvanic corrosion: that's metal to metal. To my knowledge, carbon doesn't corrode or react to metals.
 

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Adorable Furry Hombre
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Well shut my mouth and call me a corncake! Still, according to all the instructions I've read, both in Zinn's maintenance books and the seatpost installation instructions, they specifically say NOT to grease carbon fiber seatposts.

So who you gonna believe: me or Boeing?
 

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Oh, really?

Bill Silverman said:
NEVER grease a carbon seatpost. You'll wind up riding on the top tube after you hit your first bump.
Is that a fact? How come, when I overhaul people's bikes and grease their carbon fiber seat posts, this never happens to them? A seat post that slips when greased may mean that the post itself or the seat tube are off-spec in diameter. This can be dealt with by using hair spray (the low cost solution) or assembly paste (the high cost solution). It is completely incorrect to make the blanket statement you have made.
 

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Kerry Irons said:
Is that a fact? How come, when I overhaul people's bikes and grease their carbon fiber seat posts, this never happens to them? A seat post that slips when greased may mean that the post itself or the seat tube are off-spec in diameter. This can be dealt with by using hair spray (the low cost solution) or assembly paste (the high cost solution). It is completely incorrect to make the blanket statement you have made.
Psssssss-Kerry,

It should be spelt "O rly", and followed by a pic like this.


HTH! HTH! HTH! TIA! TIA! TIA! NTTAWWT!

 

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TheHeadlessThompsonGunner
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Dave Hickey said:
I'm one of those guys that says to people overreact to carbon damage BUT I would not use that seat post...
Ditto. No amount of grease, with fancy little bits of sand in it or otherwise, will make that post safe. Save it for a really, really nice shop-stool.
 

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Carbon Fiber = Explode!
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Zassazir said:
My question is, since the carbon seatpost has been damaged and the carbon exposed, will greasing it still keep it from galvanic corrosion with the aluminum? Here's a photo of the damage:
galvanic corrosion is from dissimilar metals. Carbon is CF-reinforced plastic.

So no, it's basically inert in terms of corrosion. Now the reason carbon posts seize is because of an entirely diff. reason altogether...

Anyways, I'm sorry for your loss. Buy a new one.
 

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Discussion Starter · #16 ·
I like your idea, but if I filled it with epoxy it would need sanding. Even though CF is just epoxy and fibers regardless...

I'm wondering if the rest of the CF would hold up OK and still maintain a good enough shape to be a tight enough fit... hmm
 

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Unsafe at Any Speed
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I would secure it horizontally and then pour epoxy into the damaged section. Do not overfill.

After hardening, use a knife or scalpel to just trim the fill as needed.

It looks very much like the rest of the CF (the structural part underneath) is OK. If not, it will give you enough creaks and warnings, surely.

Try it - good luck.
 

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Get some of the proper assembly paste and toss the post its gone. Buy an easton carbon post with the flat relief at the back that is designed to eliminate that sort of damage. Also if you have a seatpost clamp that is seperate from the seat tube rotate the slot in the clamp 180 degrees from the slot in the seat tube.

And yes carbon will have galvanic corrosion with aluminum if in direct contact. That is why many carbon frame builders use a layer of fiberglass to insulate the aluminum insert from the carbon.
 
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