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  1. #1
    purity of essence scotch's Avatar
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    Paint flaking off aluminum frame. A problem?

    I know nothing about the properties of the various bike frame metals.

    That said, on my 2004 Bianchi Axis - on the underside of the downtube - I've got some paint bubbling and flaking off around the threaded holes, revealing what I assume is the bare aluminum? (Please correct this if I'm wrong). I've attached an image.

    Is this bad? If so, is there anything I can/should do to treat it?

    I appreciate any advice.

    Cheers.
    Attached Images Attached Images
    Neurosis is always a substitute for legitimate suffering.

    - Jung

  2. #2
    Fred-ish rogerstg's Avatar
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    That looks like rust, which means the frame is steel not aluminum. The simple fix is to scrape off the loose paint, treat it with rust reformer and touch up with a close color. At some point you can properly sand, prime and paint the frame.

  3. #3
    purity of essence scotch's Avatar
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    Quote Originally Posted by rogerstg View Post
    That looks like rust, which means the frame is steel not aluminum. The simple fix is to scrape off the loose paint, treat it with rust reformer and touch up with a close color. At some point you can properly sand, prime and paint the frame.
    The frame is Easton Ultralite aluminum. But yeah, it does look a bit like rust of some kind.
    Neurosis is always a substitute for legitimate suffering.

    - Jung

  4. #4
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    Maybe the threaded insert is steel and it or something threaded into it is bleeding rust out onto the aluminum. You might check with a magnet.

  5. #5
    Senior Member spinbackle's Avatar
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    It's corrosion to the aluminum (aluminum oxide).
    '84 Trek 850--spinbackle-built, '85 Trek 670 Campy Nuovo Record--project, '87 Trek 560 SS/Fixed--project, '87 Specialized Stumpjumper Comp w/ Deore XT--Specialized-built, '87 Rossin Record, '03 LeMond Wayzata--commuter,
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  6. #6
    purity of essence scotch's Avatar
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    Quote Originally Posted by spinbackle View Post
    It's corrosion to the aluminum (aluminum oxide).
    Ah. Anything I can do about it? Is the frame still safe to ride?
    Neurosis is always a substitute for legitimate suffering.

    - Jung

  7. #7
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    Quote Originally Posted by scotch View Post
    Ah. Anything I can do about it? Is the frame still safe to ride?
    If it's safe to ride is a difficult question. Impossible to tell "for sure" over the 'net. Real hard in real life as well.
    You will have lost some strength, but whether it's an important amount or not can't be determined easily. Oxides are real porous compared to solid metal, so even a thick layer might not mean much.

    If it was me, I'd probably keep riding it. You'd need a bit of extra material to get away with having the bottle holder there anyhow. Might be enough to survive a bit of corrosion too.

    But you need to try to stop it. Start by getting rid of all that bubbly paint and any loose stuff. Something as easy as a light shine of grease, or a couple of layers of car wax, has a good chance of stopping the process. Or go to a (partial) repaint. Aluminum can be a bit tricky to paint, but getting the right primer will help enourmously. A yachting supply company, or a good car parts store would be able able to sell you something entirely intended for aluminium.

  8. #8
    purity of essence scotch's Avatar
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    Thanks, dabac (and everyone else). I'm going to see if a local frame painter can take a look and give me a better sense of the frame's health. I hope to be able to at least stop it, and I'll start by trying your suggestion of cleaning it up a bit and getting some grease or wax on there.

    Cheers.
    Neurosis is always a substitute for legitimate suffering.

    - Jung

  9. #9
    Senior Member Chombi's Avatar
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    I suspect that the dissimilar metals (threaded insert and frame tubing was reacting to each other from moisture induced electrolysis. Only way to stop or slow down the corrosion on the aluminum tubing is to clean off the corrosion and repant the area to seal it up so moisture cannot get at it. Now that the paint is compromised in that area. the corrosion will just keep going and probably accelerate as the bubbling and flaking paint will keep trappng the moisture against the frame tubing.
    I suggest at least removing all the corrosion and a repaint with a matching automotive spray can paint with a coats of clear to seal the paint for a long term fix.
    If you are not up to re-painting, it might actually also be better to take off the paint where you see it bubblng up and clean off the corrosion with maybe some Scotch Brite pad and WD40s till you hit bare aluminum then just give the exposed aluminum areas a spray and wipe with WD40 everytime after you ride the bike in the wet If corrosion starts again, you can just hit it again with some Scotch Brite pads to take it off.

    Chombi

  10. #10
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    Strange that the insert doesn't have any oxidation. As mentioned before, check it out with a magnet.
    Your idea of taking it to a pro is a good one. You may have to remove a lot of the paint to see how extensive the corrosion is under it. If it's not to bad and safe to ride, you can paint a black ring around the area. Kind of a custom job rather than trying to match and blend the paint. You can do that yourself with a little masking tape and a rattle can color of your choosing.

  11. #11
    purity of essence scotch's Avatar
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    Quote Originally Posted by Chombi View Post
    I suspect that the dissimilar metals (threaded insert and frame tubing was reacting to each other from moisture induced electrolysis. Only way to stop or slow down the corrosion on the aluminum tubing is to clean off the corrosion and repant the area to seal it up so moisture cannot get at it. Now that the paint is compromised in that area. the corrosion will just keep going and probably accelerate as the bubbling and flaking paint will keep trappng the moisture against the frame tubing.
    I suggest at least removing all the corrosion and a repaint with a matching automotive spray can paint with a coats of clear to seal the paint for a long term fix.
    If you are not up to re-painting, it might actually also be better to take off the paint where you see it bubblng up and clean off the corrosion with maybe some Scotch Brite pad and WD40s till you hit bare aluminum then just give the exposed aluminum areas a spray and wipe with WD40 everytime after you ride the bike in the wet If corrosion starts again, you can just hit it again with some Scotch Brite pads to take it off.

    Chombi
    Thanks, Chombi, for all the feedback. The more I think about it, the more I like the idea of at least having that entire section of the tube re-painted. Then I think, well, I've never really liked the paint job on this bike anyway, so why not have a pro just repaint the entire frame.

    At the very least, I think I will deal with the corrosion down to the bare alum and repaint that section.

    Quote Originally Posted by bobn View Post
    Strange that the insert doesn't have any oxidation. As mentioned before, check it out with a magnet.
    Your idea of taking it to a pro is a good one. You may have to remove a lot of the paint to see how extensive the corrosion is under it. If it's not to bad and safe to ride, you can paint a black ring around the area. Kind of a custom job rather than trying to match and blend the paint. You can do that yourself with a little masking tape and a rattle can color of your choosing.
    Thanks bobn. I'm going to check the holes with a magnet and I'll report back what I find. The good thing is that this is the under-side of the downtube, so it's not super visible if I end up doing my own work.

    Cheers.
    Neurosis is always a substitute for legitimate suffering.

    - Jung

  12. #12
    purity of essence scotch's Avatar
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    Magnet test was positive on the cage screw holes. So I'm guessing that for however long it's been since the screws rattled out of the holes, water has been getting in there and causing the rust/oxidation.

    For the hell of it, I sprayed some Frame Saver in there, greased up a couple of screws and closed the holes. Found a frame painter about 40 minutes away. Gonna take it to him in a few weeks.

    Thanks again for all the help, folks.
    Last edited by scotch; 04-16-12 at 08:37 PM.
    Neurosis is always a substitute for legitimate suffering.

    - Jung

  13. #13
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    Interesting that the screw holes were in steel... that needs to be sandblasted and repainted. No other way around it IMO.

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