Technical Q&A with Lennard Zinn – More greased carbon
By Lennard Zinn
Regarding your TechnicalQ&A with Lennard Zinn: Carbon tubes and lubes the consensusis unanimous that no grease be used on carbon seat posts, one thingwas not shared is how you remove grease from a seat tube if you want tochange to a carbon post from an aluminum post. If solvents shouldn’tbe used what can be used to safely remove grease that has already beenapplied? And on new frames should any prep be done to ensure thatthe frame is free of any contaminates before assembly.I want to share what I personally ran into with a new frame and carbonpost. Knowing that no grease was the only option for postinstallation 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 seatpost size (Litespeed). I assembled said bike in May 05 and in August05 I was caught in my first rainstorm while visiting the Berkshires, previousto this the bike never saw rain and is not my only bike so it wasn’t evenridden that much. When I went to remove the seat post it would barelymove. I didn’t want to twist the post back and forth but in the endhad to in some degree to get the post out. I cleaned the frame andpost again and reassembled and checked it in a month to find it was worsethan in August. Of course both times that I dealt with this someof the clear coat was lost to the seizing of the post in the frame (notfully seized of course but bad enough).Since this had already caused havoc with the post I decided to do exactlywhat 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 afterwardand then assembled. I have not had the problem again with the dissimilarmaterial seizure but know that what I am doing is not what shouldbe done.
I have always greased my own carbon posts without any problems, blissfullyignorant, as I had never bothered to read the seatpost instruction manuals(dare I say that when I write maintenance manuals!?!?). I was delugedwith mail about this subject after posting numerous manufacturers’ responsessaying not to grease carbon posts. Posted below are some horror storiesof riders who, like you, followed the instructions and did not grease theirposts. But immediately below, you will find a differing opinion on thesubject 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 thereis obviously no consensus on this.
LennardFrom Craig Calfee
Thankfully! An opportunity to dispel the myth that one shouldn’t greasea carbon post!I don’t know where the myth started, but carbon composites are not affectedby grease. Our advice is simple: If the seatpost fits tight,grease it. If it slips, de-grease it. As has been known formany years, when aluminum and carbon fiber contact each other, galvaniccorrosion can start. That is why Calfee uses a fiberglass sleeveas a seat tube shim. Aluminum seat tube (or sleeve) and a carbonpost will result in corrosion of the frame and possible seizure of thepost within the frame. A carbon sleeve on an aluminum post will resultin corrosion of the post. Salty environments accelerate this corrosion.Anodizing merely slows it down. About the only common chemical thatwill hurt carbon fiber is paint remover (which attacks the resin betweenthe fibers). But there are many solvents that will dull a nice paintjob.
It’s not that risky
I have an original 1992 OCLV bike and up until this past year I hada two-piece American Classic seatpost in it that I only occasionally removedwith no problems. The one significant difference was that I keptmine greased with just a fine amount of plain generic yellow grease.I never had a problem with either slipping or removal of the post, evenafter 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 forthe post was corroded and I replaced it with an Alpha Q carbon post (nogrease!), which I have not removed since its initial installation.No problems so far with this post, and my ride is even more comfortablenow.When I cleaned the old grease out of the frame, I did not notice anythinguntoward 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 nogrease residue and slipped the carbon post in and voilá, it wasall good. I went many years with a lightly greased aluminum post in anOCLV frame with absolutely no problems.
EricNot greasing is riskier
In response to the letters on frozen posts in carbon frames, I haveexperience with the opposite. A friend of mine got a Campy post stuck inhis steel Pinarello Opera. After a combined six hours, and one destroyedsaddle, the post was removed and packed for a trip. I have been a professionalwrench for roughly ten years and I have never seen this. The seatpost and the bike are still in operation and perfectly fine.
LanceFrom now on, I will always lube
It’s not only aluminum/carbon seatpost and carbon frames that havea nasty tendency to chemically weld: I had exactly the same problem witha Selcof
carbon seatpost and my Pegoretti road steel frame. I didn’t lube thepost when I mounted it (per manufacturer’s instructions), kept it for oneyear 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, onthe outside and removing the BB): finally, I managed to remove the seatpostreplacing the saddle with a high-torque steel wrench (normally used toun-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 hadto fight with it for almost one hour, turning and pulling, before I completelyremoved it.After that I decided it was better to lube it anyway.
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.