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The thread about seized seatposts with carbon and alloy and my own experience with alloy in my c456 seizing up has me thinking...
I want to add a Reverb to my Carbon 456, but what experiences have people had with galvanic corrosion (or whatever you like to call it), if any?
Thing is with my standard seatpost it's getting shifted up and down a fair bit during rides and that I think may be rubbing off the carbon paste I apply, and that could be why the corrosion occurs. Someone argued in another post that the paste itself doesn't help when shifting post all the time because the grit like friction stuff in it may be stripping surfaces allowing the bonding to occur more easily. Perhaps.
With a Reverb I'm not moving the post at all, so as long as there's carbon paste on it and given the coating of paint also which is less likely to wear away due to movement, it's less likely to bond?
What I don't want is to leave it in and it's fine for a year and then I need to pump up the air valve for some reason (as my Reverb on other bike sometimes needs), only to find the post has utterly bonded with the frame. Cutting a Reverb out is expensive and going to be tricky with the internals involved, plus it's at pressure!
I had to use a plastic shim to fit my reverb in my C456, so I'm assuming I wont have any issues...
Any dissimilar metals with corrode galvanically if there is no sufficient insulation between them. Regular removal and cleaning, a smear of grease is the only sensible protection. Even different grades of aluminium will corrode galvanically .
i really wouldnt worry about it. ive had an alloy seatpost in my whyte 19 steel for a couple of years without any issues. just make sure you smear a bit of grease on the seatpost before you insert it. it'll keep the water out and provide an ammout of insulation between the post and the seat tube.
How long does it take for this to happen as I have had my reverb in my carbon frame for a year, took it out and nothing even slightly corroded?
ignore that previous post. i read 'on one 456', not 'carbon 456'
I'd use some of the Pace carbon stuff or similar rather than grease, prevents slipping, but also shouldn't react with the carbon fibre in any way.
@adrec - Yeah, you should see the other thread about carbon and alloy and my well and truly bonded alloy post in carbon frame! 😀
I used carbon paste even, but constant dropping and raising during rides was wearing it off quickly, then I got lazy and didn't take the post out after rides for a couple of months... seized solid.
I could get a Reverb and still take it out after every ride. Just more concerned then about wearing away the paint and having to reapply paste stuff each time, or maybe it would be fine just leaving it in there so long as it doesn't move and plenty of carbon paste on it.
I've had my Reverb on my Carbon 456 for 18 months. I haven't suffered any galvanic corrosion at all.
This may be due to the fact I regularly whip it out, give the seat tube a clean and reapply clean paste.
Had a Joplin in mine for ages with no problems
pretty sure that's the typical "post stuck in frame" combo.ive had an alloy seatpost in my whyte 19 steel for a couple of years
For me antiseize for posts that never get moved (road/cx etc), grease for posts that occasionaly get moved, nowt but frequent inspection/wipe down for posts that are dropped several times a ride.
I had just this problem on my C455 with an alloy On One post. The metal literally started to flake away. I used to move it quite often too. That said it was in there dry. Would carbon paste have stopped it? Dunno, but I'm not sure it would....
EDIT
this is mine
https://www.flickr.com/photos/peter_atkin/sets/72157632705729229/
I've seen a Reverb that had become corroded only where the writing and logos were on it - it looked like the carbon-grip had some kind of reaction with it?! I wonder what the writing is actually made from? The pitting was so deep on the actual Rock Shox logo I was surprised a hole hadn't appeared!
Not looked at my reverb but writing is normally laser etching through the anodising. The frame will re-oxidise but not as thick as the proper anodising so I guess has more chance to corrode and you now have a slight pit for water to sit in.
PP - I suspect your post may have had quite thin anodising to more susceptible. Carbon paste or something like shimano white anti-seize should have helped.
Even a very light smear of something will help as it fills the tiny holes that water would otherwise sit in.
Andyl - it was in a carbon frame. The pitting was only apparent after the post had been removed and cleaned...it was as if a mixture of the corroded aluminium and carbon-grip had swelled where anything was etched. Luckily the post had just become tight and not stuck completely.
Edit: My experience probably won't be a problem for the longer-legged - my post was as far into the frame as it would go...for anyone with more post showing, the logo and most of the writing will be out of the frame.
PP, wow a seatpost with scabies! Never seen that before on a seatpost!
Andy, yes, I suspect you're right there.
Carbon paste is normally just stabiliser with micro balloons in there. If you have an alloy post in a carbon frame the first place they will corrode is where they are scratched or where the anodizing is worn off/removed, logos/etc.
If you move your post a lot then a Reverb is a better solution than carbon paste and waiting for the abrasive to eventually wear out one part or other.
@PeterPoddy - That's exactly how my alloy post ended up looking after I eventually got it removed.
sq225917 - Member
If you move your post a lot then a Reverb is a better solution than carbon paste and waiting for the abrasive to eventually wear out one part or other.
That's my thought really. Just I want to be sure if I just stick it in and leave it, that it won't be bonded enough that I can't take it out to pump it up or service it some day.
Easy way to make sure, Take your current post out, clean the seat tube, with cloth and alcohol and wooden stick. Then fit Reverb with lashings of quality assembly paste from TACX
http://www.chainreactioncycles.com/tacx-carbon-assembly-compound/rp-prod75810