Chi
11-27-03, 12:20 PM
Does anyone have experience with this combination? It has been known that aluminum will corrode when exposed to carbon. I've been contemplating getting a CF seatpost but my frame is aluminum. Will it be safe to use?
Road Cycling - CF seatpost & Aluminum frames
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shokhead
11-27-03, 12:34 PM
Never heard that.
Ebbtide
11-27-03, 12:45 PM
God, I hope NOT!
Dutchy
11-27-03, 05:00 PM
Carbon fibre will not corrode aluminium. Whoever told you this was wrong. How can a piece of inert "plastic" possibly affect a piece of metal? Don't worry about it, the seat post will be fine and so will the frame.
CHEERS.
Mark
CHEERS.
Mark
Thylacine
11-27-03, 06:29 PM
Hrm, interesting. I was doing some research on CF bonding, and was told buy a handful of experts that if I was going to bond CF into Al, it would be best to annodise the Al first, or order CF that has an outer layer of black dyed fiberglass ( more common than you think ). I'm not sure how much the outer resin coating changes matters ( probably quite a bit ), but I'd still be anti-siezing that post anyway. Better safe than sorry eh. I think you'll be fine.
khuon
11-27-03, 08:15 PM
I'd still be anti-siezing that post anyway. Better safe than sorry eh. I think you'll be fine.
You should never grease or anti-seize a carbon post.
The whole problem with carbon fibre and aluminum is when you try and bond them together. The bonding doesn't work very well when the aluminum has surface contamination so the aluminum must be properly prepped and oftentimes is roughed up. Carbon fiber itself is relatively immune to corrosion, however the aluminum is not and if it oxidises then the bond will be weakened by the contamination and you will get adhesion seperation. This was a quality control issue in earlier CF bikes where the bonded metal parts (dropouts, lugs, BB insert, headtube insert, seattube insert, etc...) were seperating.
Just as a note, most if not all CF frames that I know of use embedded Al (or some other sort of metal) inserts in their structure in high-wear areas (seattube, headtube, BB).
You should never grease or anti-seize a carbon post.
The whole problem with carbon fibre and aluminum is when you try and bond them together. The bonding doesn't work very well when the aluminum has surface contamination so the aluminum must be properly prepped and oftentimes is roughed up. Carbon fiber itself is relatively immune to corrosion, however the aluminum is not and if it oxidises then the bond will be weakened by the contamination and you will get adhesion seperation. This was a quality control issue in earlier CF bikes where the bonded metal parts (dropouts, lugs, BB insert, headtube insert, seattube insert, etc...) were seperating.
Just as a note, most if not all CF frames that I know of use embedded Al (or some other sort of metal) inserts in their structure in high-wear areas (seattube, headtube, BB).
Chi
11-27-03, 09:43 PM
Ok. I thought so. It seems like the carbon fibre layer itself may cause corrosion but since it's pretty much covered by a layer of resin, it's not going to cause anything bad. Since it doesn't seem like anyone's had corrosion problems with this setup, it seems like I might go and buy a CF seat post. :) My Al seat post has just about had it.