Corroded dropper post.

Jpez

Jpez

Down on the left!
So I’ve just spent 4 days in a tug of war between myself and my dropper post on my carbon frame. Never had an issue on alloy or steel frames.
I used some sort of carbon paste at assembly and re applied the couple of times I’ve serviced the dropper.
So the post is corroded. Two questions.
1. Whatda fuc if anything are you supposed to use? Carbon paste? Grease, nothing?
2. I’m going to sand off the corrosion and spray lacquer the post to seal it. Any problems foreseen for this?
 
K

kten

understands stuff moorey doesn't
Buy a new seat post, clean with alcohol and put this on it. It helps with oxidisation and avoids corrosion.

Oh, FYI I have a near new 200mm Fox dropper post looking for a new home ;)
 
Flow-Rider

Flow-Rider

Burner
Jpez said:
1. Whatda fuc if anything are you supposed to use? Carbon paste? Grease, nothing?
Click to expand...
Are you washing your bike with harsh detergents? I always try to avoid spraying a lot of water around there and using high water pressure around the seat post but I've had the same carbon frames since 2017 and never had an issue, even before that I had carbon posts in alloy frames. In the beginning, I used to check them every few months by loosening off the seat post collar and giving them a twist, but never had one stuck. I've just used the carbon juice paste on them.

Prior to all this, I bought a second hand road bike that looked like it had been washed with a harsh degreaser, everything on it was rusty around the drive train, the chain, the gear cables swelled up, and it had a stuck carbon seat post that I eventually got out.
 
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Mr Crudley

Mr Crudley

Glock in your sock
I got this on a whim when I fitted the dropper. After removing the post this week then it did do a good job of keeping out the dust and goop. Still minty there.

Unclear if it will help to stop moisture and keep the post from getting stuck but seems like a reasonable way to go.
It just doesn't look super but nicer than strapping a spare tube to the frame with a toe clip.

https://www.mtbdirect.com.au/products/bikeyoke-willy-silicone-seat-clamp-cover

20230214_154149.jpg
 
Jpez

Jpez

Down on the left!
Flow-Rider said:
Are you washing your bike with harsh detergents? I always try to avoid getting a lot of water and using high water pressure around the seat post but I've had the same carbon frames since 2017 and never had an issue, even before that I had carbon posts in alloy frames. In the beginning, I used to check them every few months by loosening off the seat post collar and giving them a twist, but never had one stuck. I've just used the carbon juice paste on them.

Prior to all this, I bought a second hand road bike that looked it had been washed with a harsh degreaser, everything on it was rusty around the drive train, the chain, the gear cables swelled up, and it had a stuck carbon seat post that I eventually got out.
Click to expand...
I’m pretty careful with washing. Only medium hose pressure and overpriced bike wash detergents and avoiding bearings etc.
Thinking about it the Highlander actually has a design flaw where it collects water in the frame and there is no drain hole. Did the Bright enduro last year in ridiculously sloppy conditions and may have been less than careful washing it at Camp crusty afterwards.
Before that I’d checked for water a couple of times and didn’t find any as some other Highlander owners have.
Also noticed there was no frame grommet for the dropper so that’s a likely culprit for water ingress.
 
wkkie

wkkie

It's Not Easy Being Green
Just pulled this out of the carbon frame and it'll be going into a steel frame next.

IMG_20240505_234342695_AE_copy_2296x4080.jpg


I've also got one similar that I pulled out of the carbon previously, went into titanium (pulled out with no issues) and now going back to the carbon.

What's the best way to clean these up? Light sand and lube before going in again?

I'm not sure I'm sold on this carbon paste / lube. The lube part is really thin and seems to almost just evaporate and the little ball things just get pushed off when you slide the post in, so might as well not even be there.

Anyone come up with a better way or method yet?
 
Dales Cannon

Dales Cannon

lightbrain about 4pm
Staff member
I have been lucky so far with carbon paste but if the bike is ridden in the rain then the post comes out and it is all wiped dry before a reinserting with C paste.
 
S

shiny

Go-go-gadget-wrist-thingy
wkkie said:
Just pulled this out of the carbon frame and it'll be going into a steel frame next.

View attachment 409223

I've also got one similar that I pulled out of the carbon previously, went into titanium (pulled out with no issues) and now going back to the carbon.

What's the best way to clean these up? Light sand and lube before going in again?

I'm not sure I'm sold on this carbon paste / lube. The lube part is really thin and seems to almost just evaporate and the little ball things just get pushed off when you slide the post in, so might as well not even be there.

Anyone come up with a better way or method yet?
Click to expand...
I will check my post in carbon frame on the weekend but I slathered it with Maxima Waterproof grease and also the inside of the seat tube. When I replaced the dropper a few months ago the old dropper was looking a-ok.
 
cokeonspecialtwodollars

cokeonspecialtwodollars

Fartes of Portingale
I think carbon paste is more suited to clamping surfaces like stems, brake levers and seat rails if you're game enough to run carbon rails... for me the seatpost just gets a coating of marine grease and reasonably frequent inspection.

I recall reading somewhere (maybe here) that once the anodising is compromised it is better to get rid of it because otherwise the reaction is concentrated on a smaller surface area and can make it more stuck quicker if that makes sense.
 
Oddjob

Oddjob

Merry fucking Xmas to you assholes
Carbon paste for the win. Slather all over the length of the shaft up to where it will be inserted to...

The carrier liquid is usually some sort of high end PTFE or silicon grease. Very good and preventing galvanic corrosion between seat posts and frames.

If you regularly ride in the rain or pressure wash your bike, check and re-lube 3 monthly.



Sent from my motorola edge 30 pro using Tapatalk
 
Staunch

Staunch

Eats Squid
cokeonspecialtwodollars said:
I think carbon paste is more suited to clamping surfaces like stems, brake levers and seat rails if you're game enough to run carbon rails... for me the seatpost just gets a coating of marine grease and reasonably frequent inspection.
Click to expand...
Carbon paste containing particulate is used to increase the friction between two smooth surfaces, such as carbon seatpost to a carbon frame, to prevent slipping. Yes, the grease/fluid/whatever that the particulate is suspended in should have anti-corrosive properties, but I guess this varies from paste to paste.

Now, I'm not implying the particulate will cause it to get stuck, but if the grease/fluid/whatever is thinner/not very water resistant then it may be washed away over time with repeated exposure to the elements.

With carbon/alloy interfaces I've just always used marine grease, like would on any other interface on a bike that doesn't involve any movement. I've been riding carbon MTB frames since 2012 and have never had a problem. The claims of 'regular' grease ruining carbon originated back in the early days with cheap, poor quality weaves. Good quality carbon won't just shit the bed from using regular grease.

TL;DR - Carbon paste only really worth if concerned about parts slipping
 
Dales Cannon

Dales Cannon

lightbrain about 4pm
Staff member
I use carbon paste and clean up and redo after wetting. Grease is counterintuitive you want minimum tightness to hold it.
 
Staunch

Staunch

Eats Squid
Dales Cannon said:
I use carbon paste and clean up and redo after wetting. Grease is counterintuitive you want minimum tightness to hold it.
Click to expand...

If carbon parts slip when greased, and they have been torqued to the correct Nm, then yes, you would be better off with carbon paste.

In saying that, I've never had any carbon/alloy interfaces slip with regular grease and the correct Nm. Depends on the tolerances/quality of the parts
 
Dales Cannon

Dales Cannon

lightbrain about 4pm
Staff member
Staunch said:
If carbon parts slip when greased, and they have been torqued to the correct Nm, then yes, you would be better off with carbon paste.

In saying that, I've never had any carbon/alloy interfaces slip with regular grease and the correct Nm. Depends on the tolerances/quality of the parts
Click to expand...
And how much loctite you use.
 
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