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Road Cycling “It is by riding a bicycle that you learn the contours of a country best, since you have to sweat up the hills and coast down them. Thus you remember them as they actually are, while in a motor car only a high hill impresses you, and you have no such accurate remembrance of country you have driven through as you gain by riding a bicycle.” -- Ernest Hemingway

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Old 10-11-05, 08:30 PM   #1
johnny99
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This is a letter from Craig Calfee (who knows a little about carbon fiber use in bicycles) to Lennard Zinn (who knows a little about bicycle maintenance): http://www.velonews.com/tech/report/...es/9023.0.html


Dear Lennard,
Thankfully! An opportunity to dispel the myth that one shouldn't grease a carbon post!

I don't know where the myth started, but carbon composites are not affected by grease. Our advice is simple: If the seatpost fits tight, grease it. If it slips, de-grease it. As has been known for many years, when aluminum and carbon fiber contact each other, galvanic corrosion can start. That is why Calfee uses a fiberglass sleeve as a seat tube shim. Aluminum seat tube (or sleeve) and a carbon post will result in corrosion of the frame and possible seizure of the post within the frame. A carbon sleeve on an aluminum post will result in corrosion of the post. Salty environments accelerate this corrosion. Anodizing merely slows it down. About the only common chemical that will hurt carbon fiber is paint remover (which attacks the resin between the fibers). But there are many solvents that will dull a nice paint job.
Craig Calfee


Elsewhere in the column, Zinn says that he always greases his own carbon seatposts and has never had a problem. YMMV.
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Old 10-11-05, 09:23 PM   #2
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You left out the fact that every other manufacturer polled said not to grease your carbon seatpost.
http://www.velonews.com/tech/report/...es/8835.0.html
Zinn said he always greased his carbon seatpost because he didn't read the instruction manual. The bottom line is that he ended up not taking a position.
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Old 10-12-05, 05:51 AM   #3
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I'm not metallurgist, but how can you have corrision between metal and a non-metallic material? That doesn't make sense to me.
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Old 10-12-05, 08:34 AM   #4
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Greasing a carbon seatpost voids most warranties. CF seatposts don't really creak or make the noise of ally posts.

I don't understand the whole issue: a CF seatpost is mostly plastic resin without the carbon exposed-how can it corrode or lead to galvanic corrosion? Carbon is metal conductor.

from an airotech site:

Galvanic coupling of materials

The objective is to avoid coupling materials from different groups unless required by economic and weight considerations. If dissimilar metal coupling is required, proper finishing and sealing techniques and guidelines are used to prevent corrosion. For example, graphite fibers, which are used to reinforce some plastic structure, present a particularly challenging galvanic corrosion combination. The fibers are good electrical conductors and they produce a large galvanic potential with the aluminum alloys used in airplane structure. The only practical, effective method of preventing corrosion is to keep moisture from simultaneously contacting aluminum structure and carbon fibers by finishing, sealing, using durable isolating materials such as fiberglass, and providing drainage.

^^ that would argue that a silicone or teflon grease should be used with CF.
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Old 10-12-05, 11:37 AM   #5
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None of the manufactures of CF seatposts recommend greasing their Composite seatposts. There seems to be a consensus from those who manufacture them. Unlike traditional alloy seatposts, the issue here does not seem to be an issue of corrossion or materials interaction between frame and seatpost.

What I've understood is some greases can reactivate the resins in the CF fabric causing the seatpost to expand over time. The result is a seatpost that is stuck into your frame. You have to cut it out to remove it.

Last edited by squeegy200; 10-12-05 at 11:43 AM.
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Old 10-12-05, 12:05 PM   #6
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Question now is:
Does anyone know where we can find carbon fiber or fiberglass seatpost shims?...
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Old 10-12-05, 02:11 PM   #7
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Quote:
Originally Posted by CardiacKid
You left out the fact that every other manufacturer polled said not to grease your carbon seatpost.
http://www.velonews.com/tech/report/...es/8835.0.html
Zinn said he always greased his carbon seatpost because he didn't read the instruction manual. The bottom line is that he ended up not taking a position.
The link you posted was earlier than this one:

http://www.velonews.com/tech/report/...es/9023.0.html

In the later post above Zinn does take a stand and he lubed his carbon post. Bottom line is Craig Calfree knows his CF and he has no problems with greasing them. I have always greased my CF posts on my Aluminum and steel bikes and never had an issue.
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Old 10-12-05, 03:09 PM   #8
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looking through the owners manual on my 06 Synapse and it states to make sure the carbon seat post is clean. no mention of lube.

it does instruct you to lube the inner surface of the binder clamp (metal) in contact with the seat tube (carbon) and the bolt threads. quoted from manual, "This will promote even application of the clamping force".
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Old 10-12-05, 04:14 PM   #9
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I wonder why nobody seems to use dry lube, like spray teflon?!
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Old 10-12-05, 04:20 PM   #10
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Quote:
Originally Posted by halimec05
galvanic corrosion. . .hmmm, yet another reason to ignore CF posts

You haven't noticed yet that while everyone is concerned with CF seatposts in allly frames, no one mentions typical ally stems and CF bars or vice versa.
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Old 10-12-05, 04:25 PM   #11
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Quote:
Originally Posted by DocRay
You haven't noticed yet that while everyone is concerned with CF seatposts in allly frames, no one mentions typical ally stems and CF bars or vice versa.
One possible reason is that it's a whole lot easier to replace a stem than a seat tube.
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Old 10-12-05, 08:54 PM   #12
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Quote:
Originally Posted by NJWheelBuilder
I'm not metallurgist, but how can you have corrision between metal and a non-metallic material? That doesn't make sense to me.
It doesn't have to be metal. The carbon fiber is conductive and the thin resin coating between the fiber and the OD of the tube is scratched away easily with installation or adjustment. It may not even exist. In regular layup, if you don't have a gel coat, sometimes the fiber is exposed in places. This is where it can conduct.

If someone had to use a lube, I would recomend one made for plastic.
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Old 10-12-05, 09:04 PM   #13
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Yet another reason to avoid Alu frames
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Old 10-12-05, 09:22 PM   #14
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Cinelli Ram bars are plagued with corrosion... The integrated stem is made of some sort of alloy (aluminum?) and they get so corroded that the paint starts to bubble and chip off! Of course acidic sweat can have alot to do with the corrosion but I wouldn't be surprised if this mating of aluminum and carbon fiber has to do with it as well...

I bought a used Ram on ebay recently for pretty cheap but I ended up removing all the paint off of the metal portion of the stem and repainting it... needless to say it looks great now!...

-Jason-
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Old 10-12-05, 09:35 PM   #15
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Quote:
Originally Posted by 2Rodies
The link you posted was earlier than this one:

http://www.velonews.com/tech/report/...es/9023.0.html

In the later post above Zinn does take a stand and he lubed his carbon post. Bottom line is Craig Calfree knows his CF and he has no problems with greasing them. I have always greased my CF posts on my Aluminum and steel bikes and never had an issue.
Huh?
"I have always greased my own carbon posts without any problems, blissfully ignorant, as I had never bothered to read the seatpost instruction manuals (dare I say that when I write maintenance manuals!?!?). ...In the end, you will have to decide for yourself what to do, since there is obviously no consensus on this.
Lennard "
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Old 10-13-05, 05:22 AM   #16
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Quote:
Originally Posted by CardiacKid
Huh?
"I have always greased my own carbon posts without any problems, blissfully ignorant, as I had never bothered to read the seatpost instruction manuals (dare I say that when I write maintenance manuals!?!?). ...In the end, you will have to decide for yourself what to do, since there is obviously no consensus on this.
Lennard "
Sorry my bad I miss read the letter to Lennard thinking it was Lennard who wrote it.
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Old 10-13-05, 05:38 AM   #17
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Here is a link that discusses CF corrosion with Titanium and Aluminum alloys from a study the Pentagon did. They probably have a strong interest in this topic.

http://www.stormingmedia.us/03/0360/A036003.html
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Old 10-13-05, 11:13 AM   #18
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Every thing that I have ever read on this subject clearly states that you should NOT grease a carbon fiber seat post, ever.
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Old 10-13-05, 01:53 PM   #19
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Quote:
Originally Posted by 2Rodies
Sorry my bad I miss read the letter to Lennard thinking it was Lennard who wrote it.
No problem. They need to change their fonts to make that clearer. Are you doing the Tour de Round Rock this weekend?
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Old 10-13-05, 02:24 PM   #20
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Quote:
Originally Posted by stonecrd
Here is a link that discusses CF corrosion with Titanium and Aluminum alloys from a study the Pentagon did. They probably have a strong interest in this topic.

http://www.stormingmedia.us/03/0360/A036003.html
That article says that there should be something between ally and CF to prevent galvanic corrosion -grease?
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Old 06-12-07, 05:42 PM   #21
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What about CF to CF? Grease or not?
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Old 06-12-07, 05:51 PM   #22
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For CF to anything, use the Tacx Carbon Assembly Paste. Works great.

http://www.competitivecyclist.com/za...MODE=&TFC=TRUE
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Old 06-12-07, 06:37 PM   #23
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Thanks for the recommendation. I wonder what's in it?

I read somewhere these dries up similar to rubber cement.
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Old 06-12-07, 07:07 PM   #24
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The problem with greasing carbon is not a chemical one. It's much simpler than that. The glossy finish of carbon, when greased, can lead to components that won't stay put, no matter how hard they are tightened. This results in folks over-torquing their carbon bits, and eventually damaging them. Use carbon paste.
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Old 06-12-07, 07:17 PM   #25
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Here are 2 recent threads that mention carbon assembly paste:
Aluminum Seatpost with Carbon Frame
EC70 stem slippage

I've used the Tacx paste on Al/Al (bars/stem) and Al/CF (carbon seatpost). It seemed to help for both - it felt (no torque wrench) like I was able to use less torque on the bolts. The seatpost was definitely more difficult to insert with the paste scratching around.

Quote:
Originally Posted by sogood
I read somewhere these dries up similar to rubber cement.
According to the product descriptions online, the paste has tiny plastic beads that increase friction without scratching the carbon clearcoat. I just wiped some excess that I had applied installing the seatpost last week - the paste is thicker due to the carrier drying, but it's not sticky or gunky like rubber cement.
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