Telling cracks from scratches

Discussion in 'Cycling Equipment' started by Paul, Jun 8, 2003.

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  1. Paul

    Paul Guest

    Since starting cycling just under a year ago I have read a lot about aluminium frames and cracking
    and so when I clean my bike I regularly check for cracks.

    Perhaps I'm getting a bit paranoid about it, considering the huge number of ally bikes being sold
    (some very expensive) it must be a sound material for frames. Anyway, I've seen a couple of pictures
    on web sites showing cracks in ally frames which show as dark hairline. My problem is that after a
    few thousand miles on gritty country roads with plenty of loose stone about my bike has plenty of
    scratches and grazes on the frame which, once a bit of dirt of oil gets in them start to look like
    these images of cracks. It's not helped by a large proportion of my frame being white.

    Some of these marks disappear once a bit of frame cleaner or GT85 has been used on them whilst
    others steadfastly refuse to shift. So, my question is, how do you tell whether something is a crack
    in the frame or just a scratch on the paint/varnish? Non of them appear to be widening or
    lengthening over time. Also, just how prone are aluminium frames to cracking (mine is a plain guage
    7005 T6 one) am I getting a bit too concerned about the possibility?

    Thanks for any thoughts, Paul.
     
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  2. Andy Dingley

    Andy Dingley Guest

    On Sun, 8 Jun 2003 21:31:26 +0100, "Paul" <[email protected]> wrote:

    >So, my question is, how do you tell whether something is a crack in the frame or just a scratch on
    >the paint/varnish?

    Go to an industrial engineering shop and buy a crack detecting dye kit. It's pretty easy to use, not
    expensive to buy, and the most complex tooling you're likely to need is a hairdryer and a UV
    blacklight (mine cost $5 from a security marking kit)
     
  3. Ajames54

    Ajames54 Guest

    On Mon, 09 Jun 2003 11:09:40 +0100, Andy Dingley <[email protected]> wrote:

    >On Sun, 8 Jun 2003 21:31:26 +0100, "Paul" <[email protected]> wrote:
    >
    >>So, my question is, how do you tell whether something is a crack in the frame or just a scratch on
    >>the paint/varnish?
    >
    >Go to an industrial engineering shop and buy a crack detecting dye kit. It's pretty easy to use,
    >not expensive to buy, and the most complex tooling you're likely to need is a hairdryer and a UV
    >blacklight (mine cost $5 from a security marking kit)

    A few days ago Jobst posted a link to the company that makes Zyglo (A product which I have used with
    great success)... they are now selling a product called spotcheck which looks from their web site
    like an excellent option for the above sort of situation.

    They also have a dealer locator on their page...

    http://www.magnaflux.com/index.asp
     
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