Small crack inside the seat tube. Should I worry?- Mtbr.com
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  1. #1
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    Small crack inside the seat tube. Should I worry?

    I'm overhauling a steel bike and I found a small crack inside the seat post. The lug around seems in very good shape. Since the bike is for a friend, I feel responsible!
    Any input is welcome, thank you

    Small crack inside the seat tube. Should I worry?-img_20180608_200115.jpg

    Small crack inside the seat tube. Should I worry?-img_20180608_195955.jpg

  2. #2
    Plays with tools
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    Something to keep an eye on for sure. The crack will likely keep going until it gets to the end of the seat tube. As long as the lug doesn't crack as well you're doing ok.

  3. #3
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    Would it be possible to stop it by welding/brazing it? thx!

  4. #4
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    Quote Originally Posted by Star View Post
    Would it be possible to stop it by welding/brazing it? thx!
    Not my area of expertise, but wouldn't that interfere with inserting a seat post? Maybe you could drill a small hole in the end to keep it from expanding? Looks like it would still be inside the top tube and not show.
    Quote Originally Posted by Oh My Sack! View Post
    Remember, there's always quilting and knitting if pedalling becomes too tough.

  5. #5
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    I like the drill a hole to stop it idea. Shouldn't have to be big, and shouldn't cut into the top tube or lug. Welding would probably also work, but then you'd have to ream it. I'm not sure if brazing would stop it or not...

  6. #6
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    Chazpat, a hole there would still fall inside the diameter of the top tube. So it seems to me a very clever idea! let's wait for the expert to endorse this solution!

  7. #7
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    Cyclingengr thank you for your input, I agree:
    - Hole drilling - preferred solution (it won't cut anything else than the cracked part of seat tube wall, easily clearing the lug and top tube wall)
    - Welding (maybe reaming with a Dremel would be imprecise but enough for a seatpost)
    - Brazing - not very sure if that would stop it, but it is just an intuition without much scientific background

  8. #8
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    Have fun drilling a hole at the end of that crack.

  9. #9
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    Quote Originally Posted by customfab View Post
    Have fun drilling a hole at the end of that crack.
    Because of the angle you'd have to drill at? Looks like if you removed the binder bolt, you could go pretty straight at it.
    Quote Originally Posted by Oh My Sack! View Post
    Remember, there's always quilting and knitting if pedalling becomes too tough.

  10. #10
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    Yup, stick a drill bit through the binder slot, drill the crack, call it good.

    -Walt

  11. #11
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    update

    Done, I had to enter with a bit flexible support. Thanks everybody for the suggestion!

    Small crack inside the seat tube. Should I worry?-img_20180608_200115.jpg
    Small crack inside the seat tube. Should I worry?-img_20180611_161536.jpg
    Small crack inside the seat tube. Should I worry?-img_20180611_161653.jpgSmall crack inside the seat tube. Should I worry?-img_20180611_161811.jpg

  12. #12
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    That looks good.
    And after calming me down with some orange slices and fetal spooning, ET revealed to me my singular purpose.

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