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Tech Talk: Reports
Technical Q&A; with Lennard Zinn - More greased carbon
By Lennard Zinn
VeloNews technical writer
This report filed October 11, 2005

Dear Lennard,
Regarding your Technical Q&A with Lennard Zinn: Carbon tubes and lubes the consensus is unanimous that no grease be used on carbon seat posts, one thing was not shared is how you remove grease from a seat tube if you want to change to a carbon post from an aluminum post. If solvents shouldn't be used what can be used to safely remove grease that has already been applied? And on new frames should any prep be done to ensure that the frame is free of any contaminates before assembly.

I want to share what I personally ran into with a new frame and carbon post. Knowing that no grease was the only option for post installation I cleaned the frame's seat tube with alcohol before assembly, this was a new frame that came with an aluminum insert milled to the seat post size (Litespeed). I assembled said bike in May 05 and in August 05 I was caught in my first rainstorm while visiting the Berkshires, previous to this the bike never saw rain and is not my only bike so it wasn't even ridden that much. When I went to remove the seat post it would barely move. I didn't want to twist the post back and forth but in the end had to in some degree to get the post out. I cleaned the frame and post again and reassembled and checked it in a month to find it was worse than in August. Of course both times that I dealt with this some of the clear coat was lost to the seizing of the post in the frame (not fully seized of course but bad enough).

Since this had already caused havoc with the post I decided to do exactly what I know should never be done, I added some grease. Not a lot; just a film, on the post and frame, and wiped with a clean rag afterward and then assembled. I have not had the problem again with the dissimilar material seizure but know that what I am doing is not what should be done.
Tom

Dear Tom,
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!?!?). I was deluged with mail about this subject after posting numerous manufacturers' responses saying not to grease carbon posts. Posted below are some horror stories of riders who, like you, followed the instructions and did not grease their posts. But immediately below, you will find a differing opinion on the subject of whether to grease a carbon seatpost from carbon guru Craig Calfee. In the end, you will have to decide for yourself what to do, since there is obviously no consensus on this.
Lennard

From Craig Calfee

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

It's not that risky
Dear Lennard,
I have an original 1992 OCLV bike and up until this past year I had a two-piece American Classic seatpost in it that I only occasionally removed with no problems. The one significant difference was that I kept mine greased with just a fine amount of plain generic yellow grease. I never had a problem with either slipping or removal of the post, even after leaving it in for a few years with accumulated grime on it. As a matter of fact, the reason I removed it was that the set screw for the post was corroded and I replaced it with an Alpha Q carbon post (no grease!), which I have not removed since its initial installation. No problems so far with this post, and my ride is even more comfortable now.

When I cleaned the old grease out of the frame, I did not notice anything untoward inside so I do not think that the grease created any problems. I just scrubbed it out thoroughly with a shop rag until I could feel no grease residue and slipped the carbon post in and voilá, it was all good. I went many years with a lightly greased aluminum post in an OCLV frame with absolutely no problems.
Eric

Not greasing is riskier
Dear Lennard,
In response to the letters on frozen posts in carbon frames, I have experience with the opposite. A friend of mine got a Campy post stuck in his steel Pinarello Opera. After a combined six hours, and one destroyed saddle, the post was removed and packed for a trip. I have been a professional wrench for roughly ten years and I have never seen this. The seat post and the bike are still in operation and perfectly fine.
Lance

From now on, I will always lube
Dear Lennard,
It's not only aluminum/carbon seatpost and carbon frames that have a nasty tendency to chemically weld: I had exactly the same problem with a Selcof
carbon seatpost and my Pegoretti road steel frame. I didn't lube the post when I mounted it (per manufacturer's instructions), kept it for one year or so,
then I wasn't able to move it when I had to.

No chance with penetrating oil (waiting DAYS and using lots of it, on the outside and removing the BB): finally, I managed to remove the seatpost replacing the saddle with a high-torque steel wrench (normally used to un-screw the bolts on car wheels) and giving a brutal display of pure force.

The post started to turn after several all-out attempts, with a loud 'crack' (at that point, I was ready to destroy it, if I had to). I had to fight with it for almost one hour, turning and pulling, before I completely removed it.

After that I decided it was better to lube it anyway.
Alberto


Technical writer Lennard Zinn is a frame builder (www.zinncycles.com), a former U.S. national team rider and author of several books on bikes and bike maintenance including the pair of successful maintenance guides " Zinn & the Art of Mountain Bike Maintenance" and "Zinn & the Art of Road Bike Maintenance."Zinn's regular column is devoted to addressing readers' technical questions about bikes, their care and feeding and how we as riders can use them as comfortably and efficiently as possible. Readers can send brief technical questions directly to Zinn. Zinn's column appears here each Tuesday.