Are these cracks?
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  1. #1
    RoadBikeReview Member
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    Are these cracks?

    Purchased this 2015 Giant Propel Advanced SL2 secondhand, but noticed these scratches or possibly cracks on the frame. Can someone please help me in identifying what they are? I can take more pictures or at different angles or lighting if necessary. Thanks!

    Edit: I did the sound test, but there isn't any significant change in pitch of the ringing. (I don't know how reliable that test is).

    Here's the pictures: https://imgur.com/a/GIaNFD0

  2. #2
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    I looked at the photos.

    The spiderweb photo-without seeing the exact location, I'd say it's a fault of a clear coat.

    The line on the side of the tube-I'm inclined to say it's a crack. Since you've already done the coin test and it's inconclusive to you, I suggest another test.

    Brush some white nail polish over the alleged crack, then see of the nail polish cracks as well. Or place a magic marker dot at each end of the line and watch to see if the crack progresses beyond the dots. Those will be clues the tube is failing. And continue to perform the coin test at least once a week. It's a good test and you'll gain experience by recognizing what sounds normal and what may change.

  3. #3
    'brifter' is a lame word.
    Reputation: cxwrench's Avatar
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    I'm of the opposite opinion, the spider web in the 3rd photo definitely looks like a crack to me. I'd need to take a better look at the first 2, they are a little weird looking. I'm 95% the 3rd is a crack from outside impact.
    I work for some bike racers
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  4. #4
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    Ok, thanks for the advice Peter, will do the nail polish test asap.

  5. #5
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    Also, the spiderweb one is located on the top tube - about 2/3rds up the tube. https://www.giant-bicycles.com/us/pr...nced-sl-2-2015 That is a link to the bike and the spiderweb is under the O of "propel"

  6. #6
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    Thanks for the additional link.

    I'll now have to agree with cxwrench on his opinion of the spiderwebbing, and here's why.

    Looking at everything, I'm guessing both suspect areas align pretty well vertically. Generally, manufacturers can thin the carbon in the tube middle sections, retaining strength while maintaining low weight.

    However, that creates a weak spot when it comes to frontal impacts. I'll bet the frame suffered a frontal impact in its previous life and you're seeing the result.

    I'd still follow my suggestions but instead paint over both "cracks" mark them as above and see if they progress or cause the nail polish to crack. And keep performing the coin test.

  7. #7
    Russian Troll Farmer
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    Looks to me like it got hit. Handlebar hit, maybe? Or hit during transport? FWIW, that part of the tube is where it's thinnest...
    "L'enfer, c'est les autres"

  8. #8
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    How many miles you reckon is a good enough of a test to see if the nail polish cracks?

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