Inspecting Carbon Fibre Bike frames

This was reproduced from a work forum and is an interesting read
NDT Capability when inspecting Carbon Fiber Bike frames.

Carbon Fiber bike frames are very difficult test and for that reason alone, most reputable manufactures will actually just replace the fame under warranty as long as the original owner has not abused the frame.

Checking if a frame is cracked is not that simple, if the crack is thru the full thickness of the carbon fiber there is a good chance that it will appear on a radiograph. However, if the crack does not go thru the full thickness of the carbon, it may still be cracked, however this may not appear on an x-ray.

Additionally Carbon Fiber is highly susceptible to a phenomena called Barely Visible Impact Damage (BVID). The Carbon Fiber looks fine on the surface, however the structural integrity of the fibers below the surface is less than satisfactory. The amount of damage below the surface varies depending on the type and amount of force of the impact. NDT is able to detect this damage using ultrasonic’s, if they have a suitable standard to compare the frame against. If not detected or repaired this can lead to catastrophic failure. Could get really ugly on a downhill run.

For those of you that do ride carbon frames my suggestion is to handle them with great care. If you have had some sort of impact damage or it appears there is a crack on the surface get it checked. Check you warranty booklet and be familiar with what you can and can’t claim.

On another note, Carbon Fiber is also Hydroscopic (absorbs water), therefore if you get a chip in your paint/gel coat get it fixed ASAP, as this also can have detrimental affects to the strength of your frame. Water absorption can cause a corrosion cell to form on those bikes that are glued together to aluminum lugs, or have aluminum lugs as strengthening members under the carbon fiber. I’ve had 3 TREK OLCV 5500 frames replaced for this reason alone.



  1. Carbon has many of the qualities that the other materials have, it can have the comfort of steel and titanium, the stiffness of alloy and its lightness is difficult to beat by any one of them. The weave of the carbon and unlike steel it is not easy to repair.

  2. walt echols says:

    For chips in the paint/gel coat, is the best fix to apply touch up paint?

    1. Mark Croonen says:

      Basically to fix it any chips in the gel coat you need something which is going to create a waterproof barrier. While paints can be used, I have also heard that clear coat nail polish works well. Easy to apply, waterproof and works with any colour. Just make sure the chipped area is dry, last thing you want to be doing is sealing in water.

  3. Steve Katz says:

    I was just told by Specialized, upon inspecting my 2005 Roubaix Comp frame, that a nickel sized area that is gone from the upper part of the seat tube, is “impact damage.”

    You can see the checkerboard pattern from the carbon very clearly.

    The question is whether 1) is Specialized living up to its warranty by only giving me a discount on a new bike? 2) Is the bike ridable?

    Thank you.

    Steve Katz

    1. Joe McColl says:

      I just had Specialized repond to me in the same fashion. S Works SL2 has never been crashed and it has a crack in the rear chainstay they claim form impact and will sell me a new frame at a 25% discount. This is a farce and if it is not rectified to my satisfaction, I will be posting on every cycling blog and pickiting outside of the new Specialized Concept store opening in Tampa in the near future. I have heard multiple horror stories of Specialized not standing behinf thier warranty.

      1. Mark Croonen says:

        The whole warranty issue really is interesting, because I don’t think it is something we don’t give a lot of thought to when purchasing, sure we gloss over the fact of how long the warranty is but that is about it, not how easy it will be to claim.

        Having just had my frame replaced under warranty I would just like to say that Giant bikes (Australia at least) were awesome. I simply took the bike into the LBS where I had purchased the bike, A day later the Giant rep inspected the frame and 8 days later a new frame arrived at the LBS no questions asked. The old frame was 4 years old and had about 50,000k and was replaced with brand new frame. You have got to be happy with that.

        It is also the reason why I will buy a lot of bike parts overseas but buying frames and new bikes , especially Carbon is something I will always do locally. Unfortunately let’s face it, if you are going to buy a carbon frame you are going to have to accept that it will fail sooner or later and being able to get good local warranty support is well worth it.

    2. jim says:

      Hey I’m a USF grad thinking about returning to Tampa, is Flatwoods park still a good place to ride? What about riding to the park- is that road too busy now?

  4. Thomas says:

    These bicycle companies selling these fragile bicycles at exorbitant prices on one end and then not keeping these carbon fiber bikes under full warranty, is just financial exploitation and a form of usury.

    We shouldn’t buy CF if they’re not going to fully back its use!

  5. Campbell says:

    Interesting comments. I am a keen cyclist but also have 15 yrs service in the aerospace industry where i daily inspect impacted carbon fibre components in an research and development field using ultrasonincs. I was considering starting an inspection service from home. Have inspected a few stems , seat posts and frames in the past and yes damage was evident. Perhaps due to impact or fatigue as a result of forces exerted by rider over time on the road. Problem highlighted above is yes you may find damge but will the supplier replace expensive components free of charge. I currently inpsect my and friends bike for piece of mind / reassurance of saftey. (UK based) Interested in your views on my potential venture?? Worth while? Not basedon profit but firstly for saftey in mind.

    1. Jez says:

      Hi Campbell,
      Very interested to read your comments on the service you are thinking about. I was having the same thoughts but I do not have the facilities as you obviously do!

      Would be interesting to have a chat.

      Let me know and we can sort something

    2. dan padoin says:

      i purchased aderoa frame , neo pro made from carbon fibre . i found the frame to vibrate on downhill descents . i had a second opinion done on the frame with similar results of oscillation occurring at high speeds . my understanding is you are from england , is there someone from ontario canada who could test this frame and determine the origins of this defect

      thank you dan padoin

    3. Brian T says:


      I have a 1987 Dave Scott Ironman Carbon. It has carbon stays and tubes fitted into steel (or possibly aluminium) lugs. I want to restore the bike and modernize, but I want to test if it is safe. I’m interested in your services.

    4. RichardE says:

      Hi Campbell
      yes this is a great idea. Having just had a very serious RTA I am in something of a dilema. My somewhat unique carbon frame has emerged seemingly unscathed. Though this would be paid for by someone else’s insurance I am loathe to scrap the frame if it is actually as undamged as it appears. If you have started this service or indeed are able to do something as a one off, let me know cost etc. Please email:

  6. Neil says:

    Hi Campbell,
    Interested to see if you are inspecting frames…. If so drop me an email or reply here as I’ve a carbon track frame which may have a crack in the BB / sea tube are? 2 lines around 1cm each which do not have the ‘feel’ of Scratch.


  7. earl rise says:

    Hi Campbell
    I reckon your idea for a venture examining carbon frames is a great idea. Would it be possible for you to have a look at a small crack or flaking of paint (don’t know which it is!) on my frame if I sent you a pic?
    Can’t remember my word press ID or password so perhaps you can email me at:


  8. Gavin key says:

    hello all just been reading your comments about carbon frames failing i’m currently in a warrnety disagreement with a online bike store called wiggle! i found what appered to be a crack on my down tube just starting to form i sent it back to my dealer wiggle who then sent it on to manafacture Basso for inspection upon inspection Basso tell me its not a crack but a surface mark between to layer of carbon a surface mark by definiton can not be between to layers any thoughts? and are going to repair it i fear it may not be safe to continue riding? its coming upto 6 weeks with no bike

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