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How bad is this crack in my carbon frame?

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  • December 14, 2015 at 11:39 am #25159
    Robertmi

    Dear fellow riders,

    This is my first post here…. Please be kind….

    I got my first ever carbon bike a coupe of weeks ago and I guess I cracked the seat tube by over tightening the seat post! 🙁

    I have since done extensive research and reading on the subject (too late I know) so I know I should get a torque rench and be more careful but my main concern at this stage is how bad this crack really is and how to repair it…

    https://www.dropbox.com/s/ifqzo6w0daczms4/Photo%2014-12-2015%2C%2012%2013%2031.jpg?dl=0

     

    I hope I can get some feedback from some of the more experienced riders out there.

     

    Thanks in advance!

     

    Robert

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  • December 17, 2015 at 11:05 am #863875
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    DaveE128

    That looks like it needs

    That looks like it needs repair to me. As alluded to by others, you ought to get the seat post checked too.

    Sorry that you’ve had to learn about using a torque wrench the hard way 🙁 It’s a pity that the retailer didn’t warn you about this. It also applies to bolts on the stem if you even need to adjust those, as the steerer of the fork, which you can’t see inside the (usually metal) stem and anything else that clamps something carbon.

    Hope you can get it fixed for not too much money.

     

    December 14, 2015 at 10:37 pm #863873
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    Nixster

    So like the others said get

    So like the others said get it checked, probably a cheap repair as its not ‘structural’ although granted it is keeping your saddle on.  

    However, how you managed to get the seat tube to deform that much without crushing the seat post I’m not sure. The post in the photo looks to be carbon, I’d get that looked at too as there’s a good chance it has crush damage. And if that fails you will notice it as you’ll be sitting on the ground quite suddenly!

    December 14, 2015 at 9:11 pm #863871
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    VeloUSA

    Robert – Understand that

    Robert – Understand that carbon is layered during manufacturing. What may not be noticeable are microscopic fractures in the underlying layer/s. At some point in time you may experience a complete failure. This is something you don’t want happening while your toosh is planted on the saddle. As others have mentioned get it checked out not by your LBS but by a reputable carbon repair shop. Be safe rather than sorry.

    December 14, 2015 at 8:06 pm #863869
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    Richard1982

    Hi Robert
    Hi Robert 🙂

    As others have said I would get it checked out… But don’t worry, in all likelyhood it wouldn’t be expensive to fix.

    Over the summer I had quite a bad accident than resulted in the top tube of my bike being completely snapped through and cracked around in another place. At first I was horrified at the thought of having to buy a new frame, but after going to my local carbon repair place it turned out to only cost £150 for repairs, including painting.

    The place I used (in North Yorkshire) is called Hansell Composites (http://www.fibre-lyte.co.uk/). If there isn’t a repair place near you then perhaps you could post it to them. They also do re-painting, etc.

    Richard

    December 14, 2015 at 6:05 pm #863867
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    FatAndFurious

    Whilst I don’t own a carbon

    Whilst I don’t own a carbon frame, from a purely materials science point of view any crack is bad news as they act as stress concentrators and propagate. Stress is proportional to the inverse of the radius of the “curve” – a crack is a very very tight curve, so stress gets very very high.

    This is why the gap in the frame for the seatpost has a circular cutout bigger than the gap so that the stress in that area is kept to a minimum. A “square” notch would concentrate stress in the 90 degree corner.

    I wouldn’t want to ride it. I’d suggest an check and repair approach.

     

    December 14, 2015 at 4:24 pm #863865
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    Robertmi

    Thanks for the feedback. I’m

    Thanks for the feedback. I’m quite sure its not just a crack in the paint (I tried the coin test and it sounds different). However, the crack does not go all the way through as there is no sign of it on the inside of the tube…. Thanks for the hint re using the short end of the allen key for tightening!

     

    In the meantime, I have been out with the bike for a 57km ride this afternoon and it doesnot seem to have changed…. also, no squeeks during the ride (I was on the look out)

    December 14, 2015 at 2:44 pm #863863
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    peted76

    Any crack in carbon is a bad

    Any crack in carbon is a bad crack. Get it sent off to be checked and or repaired.

    December 14, 2015 at 1:24 pm #863861
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    Cyclespeed Tours

    Doesn’t look too bad to me,

    Doesn’t look too bad to me, but it’s hard to tell without seeing it in the flesh.

    Could just be the paint that’s cracked off. 

    Can you see any evidence of a crack beneath the paint?

    For future reference, use carbon paste, it helps increases friction and you can use less torque. 

    And as a guide, I would tighten as hard as you can using the SHORT end of the allen key. That should be about 4 to 6Nm, which is plenty.

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