Galvanic corrosion gurus, another stuck dropper post in carbon frame thread!

Did someone say hammer?
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Travis22 said:
Thanks Knuckles.

I guess im my case a more regular cleaning and regreasing would be best. Least it came out with zero effort despite the corrosion.

Does this require any special cleaning, any tips for cleaning the corrosion? (Guess the best solution is a carbon seatpost?)

Travis.
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A high quality Ti seatpost would be fine too. Commercial grade Ti has a dense oxide layer on the surface which insulates against galvanic potential.

Even better would be a cast iron post, and even better again would be a platinum post.

Galvanic corrosion isn't like rusting (oxidisation) it won't continue to happen once the contact is broken. You could try using some steel wool and caustic soda to remove the anno up to the insertion point, then greasing and fitting. Full bare alloy will corrode slower than a patchy anno job.
 
Slacker!

So motivated by student number up there, I went past repco and grabbed some locktite freeze and went about spraying it all over the shop and a little landed where I wanted.

I am happy to report, that while the post is not yet completely free of the bike, it now can be moved side to side - so that's a win as far as I'm concerned, just needs an hour or so of consistant screwing
 
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pharmaboy said:
Slacker!

So motivated my student number up there, I went past repco and grabbed some locktite freeze and went about spraying it all over the shop and a little landed where I wanted.

I am happy to report, that while the post is not yet completely free of the bike, it now can be moved side to side - so that's a win as far as I'm concerned, just needs an hour or so of consistant screwing
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Sounds like my wife. Got a spare hour or so?
 
Fuck, should have taken photos - MINES OUT!!!!

Freeze for the win. It was a deadset mess in there though, annodizing, what annodizing?

Cleaned, sanded, greased, reinstalled and will take seat post out every couple of weeks now. I really think it's a wet weather, bike cleaning thing eg, putting bike upside down and water going down Seattube
 
Ive ditched the Giant post and got a 10year old Thomson in there now.

Zero sign of any more corrosion, but i have taken it out a few times to check, re grease as opposed to the extended time the factory post got without looking. Who knows...

Still wash the bike after every ride. Use diluted simple green now as opposed to wd-40 bike wash (cheaper tho i dont think as good fwiw).

Travis.

Ps congrats on the win pharmaboy!
 
Every couple of weeks taking it out, surely there is an easier solution that that, but reading this - maybe there isn't http://velonews.competitor.com/2009/10/news/road/stuck_seatpost_99640. The KS posts seem to have more problems with this than the Reverb on a quick MTBR browse too. Get as much carbon paste on the post and frame as you can is your best bet?

My accidental solution has been to run a 30.9 Reverb post in a 31.6 seat tube with a 100mm long shim. I bought the dropper in 30.9 to “future proof” it, but taking it out of the bike has been a piece of cake (once after two years). If you have a 30.9 frame obviously can’t do this.
 
Update:

I've decided to pull down the entire bike and get the post out

I haven't had time to do this, but think its the most sensible approach

Still haven't made use of Stoo's awesome custom clamp

Hopefully get some time soon
 
Okay bit of a dig. Have a reverb dropper stuck in carbon frame. Happened once before but some wd40 and a bit of wiggling got the job done. Problem this time is that hasnt worked. My post is almost all the way in frame, so no outer tube to work with. I am reluctant to put much sideways force into inside tube. I notice the reverb has a threaded collar. Can i use that to try and get it twisting in frame or will overtightning it damage something?

Sent from my SM-G900I using Tapatalk
 
outtacontrol ... I'd try the freeze spray thing above ^

Travis22 said:
Still wash the bike after every ride. Use diluted simple green now as opposed to wd-40 bike wash (cheaper tho i dont think as good fwi!
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a plastic bag or cling wrap around the seat clamp ... And or seal collar if you have a dropper, every time you wash the bike ... Or alternatively, take the post out before the wash ... And leave the post out over night to let moisture evaporate out during storage ... is my suggestion.

pharmaboy said:
Cleaned, sanded, greased, reinstalled and will take seat post out every couple of weeks now. I really think it's a wet weather, bike cleaning thing eg, putting bike upside down and water going down Seattube
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I reckon once a month removal as part of a relube routine is prolly enough.
storing upside down might be good and bad depending on how much moisture is in the seat tube ... And what the drainage holes are like in the frame/BB.

as above re: Bike wash and plastic bag treatment to stop water ingress is another preventative maintenance thing
 
Got it out. Was worried about damaging the dropper by twisting too hard, but Ducky gave me the heads up that there is a keyway between the inner and outer tubes so ok within reason. My problem is my frame runs a stealth cable that enters on top of the down tube near the bb. To stop water getting in i seal the hole with silicon around the cable, so you can't remove the post without breaking the seal.

Sent from my SM-G900I using Tapatalk
 
I hope i don't get chewed up for reviving this old thread but it really is the best thread i've found on the galvanic corrosion of carbon fibre frames and aluminium seat posts.

I've got a 30.9mm dropper (Giant) that i want to put into a 31.6mm carbon seat tube. I've also got an aluminium shim from Problem Solvers. It all fits together perfectly but because of this corrosion thing i'm thinking real hard about what i'm going to do.

Ideally i'd use a shim made of a material that is non-compressible, electrically non-conducting and is manufactured in thin sheets of around 0.4mm in thickness. If such a material is available and works in practice then maybe it's a good idea to buy seatposts a size smaller then insulate.

I could just use the aluminium shim and check/clean once a month but i'm more of a maintenance once every 6 months type of person.. I'm also thinking that the aluminium shim will wear spots into the post and frame - I contacted Problem Solvers directly and they don't recommend this shim for carbon seat posts for this reason.

Any ideas?
 
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