Sram Carbon Crank Damage

bl0k3
bl0k3 Posts: 12
in Workshop
I have just purchased a second hand Quarq power meter with carbon cranks.
noticed that they have some damage possibly from the chainset dislodging and scraping up against something on the frame (this wasn't shown in the advert).

Looking to get opinions on whether this is superficial damage or potentially structural. I know that the layers of paint/lacquer etc will be fairly thick but unsure whether the scratch has penetrated through to the carbon.

I have uploaded some images to illustrate the extent of the damage.

I




Opinions?

Cheers.

Comments

  • whyamihere
    whyamihere Posts: 7,700
    That's definitely done some damage to the carbon. I wouldn't be happy riding that.
  • redvision
    redvision Posts: 2,958
    Send it back.
  • webboo
    webboo Posts: 6,087
    That’s not a scratch.
  • bl0k3
    bl0k3 Posts: 12
    Thanks for the opinions.

    The lighting on the first picture does slightly exaggerate the depth of the damage, although I do agree that it is concerning.

    The thing that makes me unsure it that I can't see any material resembling carbon showing through, i.e. no fibres etc.

    I'm not sure it's even possible to source a singular crank arm, or I would just do that? Anyone know of a way to source something like this?

    Cheers.
  • lesfirth
    lesfirth Posts: 1,382
    If I had legs like Chris Hoy I might hesitate before sprinting with a crank like that but I dont so I would ride it without a second thought.
  • mr_evil
    mr_evil Posts: 234
    bl0k3 said:

    ...The thing that makes me unsure it that I can't see any material resembling carbon showing through, i.e. no fibres etc...

    That looks like it's been abraded through quite smoothly rather than cracked or torn, in which case the fibres won't poke out for you to see. It's the same if you look at the top of a carbon steerer tube that's been cut properly - the edge looks like a solid black material, even though the cut has gone right through all the fibres.
    https://mrevil.asvachin.eu/
  • redvision
    redvision Posts: 2,958
    It looks like it's around the area a cadence sensor may have been attached, so could a zip tie have been used and gradually cut in to the crank arm?

    Like I said in earlier post, send it back. Even though you purchased second hand, if you hadn't seen images of the damage you are within your rights.
  • bobones
    bobones Posts: 1,215
    edited December 2019
    bl0k3 said:

    Thanks for the opinions.

    The lighting on the first picture does slightly exaggerate the depth of the damage, although I do agree that it is concerning.

    The thing that makes me unsure it that I can't see any material resembling carbon showing through, i.e. no fibres etc.

    I'm not sure it's even possible to source a singular crank arm, or I would just do that? Anyone know of a way to source something like this?

    Cheers.

    Looks like the low limit screw on eTap FD has been a bit too close to the crank arm, which is a common problem with the eTap FD and some frames. I would have no hesitation in continuing to ride with this as it is purely superficial IMO. I believe SRAM supplied shorter limit screws to people affected by this problem.
  • bl0k3
    bl0k3 Posts: 12
    Thanks Bobones.

    I have sent a query to SRAM on this to see if I can get their opinion based on the carbon layup and obviously they will have the knowledge.

    Cheers

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