Cracked Carbon Frame - TREK ELITE 9.7

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Comments

  • aaronmroach
    aaronmroach Posts: 341
    The damage to the outer epoxy resin / paint is similar to that of BVID (Barely Visible Impact Damage) I see a lot of this type of damage at work.

    Not to throw blame but has it been lent against something in a shed / garage. It would be very very unlikely a hair line crack would propagate from a pre-drilled hole unless some impact damage / material distress has occurred at some time of its life. Or snagged on the cable and pulled the rivet??

    If it has genuinely had no miss treatment of any kind (be honest with your self) then it is most definitely a manufacturing fault probably caused by a rivet that has been over formed in the pre-drilled hole or the holes were not drilled 100% correctly and the forming of the rivet has stressed the structure.

    If there is no warranty claim you can have it repaired but it will cost and is not 100% effective.
  • bennett_346
    bennett_346 Posts: 5,029
    aaronmroach wrote:
    The damage to the outer epoxy resin / paint is similar to that of BVID (Barely Visible Impact Damage) I see a lot of this type of damage at work.

    Not to throw blame but has it been lent against something in a shed / garage. It would be very very unlikely a hair line crack would propagate from a pre-drilled hole unless some impact damage / material distress has occurred at some time of its life. Or snagged on the cable and pulled the rivet??

    If it has genuinely had no miss treatment of any kind (be honest with your self) then it is most definitely a manufacturing fault probably caused by a rivet that has been over formed in the pre-drilled hole or the holes were not drilled 100% correctly and the forming of the rivet has stressed the structure.

    If there is no warranty claim you can have it repaired but it will cost and is not 100% effective.
    Frames are riveted?
  • The Rookie
    The Rookie Posts: 27,812
    The cable clip is riveted on.......
    Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.
  • sceptic
    sceptic Posts: 4
    I have seen frames of Trek full suspension models cracked in the same place. The assumption is that it is from braking force from the disc brake system. Your bike shop should be supportive with you, Trek are usually VERY good. A lifetime frame warranty (original owner) is exactly that. Keep pushing and if necessary try a different Trek dealer. Good luck!
  • 02gf74
    02gf74 Posts: 1,171
    stone damage? so how come no marks on the seat stay? I would get back to Trek on this.
  • dv69
    dv69 Posts: 19
    mtbcy wrote:
    And photo of the OUTSIDE of the frame - showing NO impact damage.

    Can you get another picture of the rear of the bike? I'm struggling to see where the braking surface of the rear disc is, I'd expect it to be where the orange line is in the picture below but I can only see the plastic spacer on the cassette.

    o8gun5.jpg
  • njee20
    njee20 Posts: 9,613
    You can clearly see the rotor lower down, can't work out if the wheel's in the dropouts though. Why is the exact placement of the rotor relevant? The stay won't crack in line with where the rotor is.
  • dv69
    dv69 Posts: 19
    edited December 2012
    njee20 wrote:
    You can clearly see the rotor lower down, can't work out if the wheel's in the dropouts though. Why is the exact placement of the rotor relevant? The stay won't crack in line with where the rotor is.

    I was trying to visualise how the seat stay would flex under compression when braking and noticed the rotor was out of place which makes it harder to visualise what is happening. There has been research about compression fatique of carbon fibre when notched or drilled so the rivetted hole could be concentrating stress on the stay.
  • njee20
    njee20 Posts: 9,613
    But the flex will be around the calliper mounts. Yes a bigger rotor will mean more 'leverage', but it doesn't transfer where that load is applied.
  • dv69
    dv69 Posts: 19
    njee20 wrote:
    But the flex will be around the calliper mounts. Yes a bigger rotor will mean more 'leverage', but it doesn't transfer where that load is applied.

    The mounts don't exist in isolation, the forces from the drop-out region are transferred to the seat stay and chain stay. When braking, the caliper mounts transfer forces into the stays. A bigger rotor providing bigger leverage will alter the direction of applied force to the seat stay. The larger the rotor, the more the seat stay is subjected to bending because torque (force x distance from point rotation) is larger.
  • njee20
    njee20 Posts: 9,613
    Yes as I said, but the exact physical location of the braking surface isn't necessarily going to be the point of failure.
  • dv69
    dv69 Posts: 19
    njee20 wrote:
    but the exact physical location of the braking surface isn't necessarily going to be the point of failure.
    You're the only person to suggest this! You're effectively saying: "something you didn't mention isn't possible". I hope you're not working through a long list of things I never said :)
  • njee20
    njee20 Posts: 9,613
    :roll:

    You said:
    Can you get another picture of the rear of the bike? I'm struggling to see where the braking surface of the rear disc is, I'd expect it to be where the orange line is in the picture below but I can only see the plastic spacer on the cassette.

    That's an irrelevance. There's clearly an Avid G3 rotor in the picture, 160 or 140mm. If it was a 200mm it could be relevant because of the forces involved, but it's clearly not, and the exact placement of the braking surface isn't significant.
  • dv69
    dv69 Posts: 19
    njee20 wrote:
    :roll:

    You said:

    I know what I wrote, I never mentioned that the size or location of the rotor was significant. I asked if the OP had another picture because the close ups I could find online of the same bike were all of the drive side.
    njee20 wrote:
    That's an irrelevance. There's clearly an Avid G3 rotor in the picture, 160 or 140mm. If it was a 200mm it could be relevant because of the forces involved, but it's clearly not, and the exact placement of the braking surface isn't significant.

    You are imagining what I may be thinking and then telling me what you think I am thinking is incorrect. I am not thinking what you think I am thinking. Leave the mind reading to Derren Brown.
  • njee20
    njee20 Posts: 9,613
    Am I? Oh right. Thanks.
  • supersonic
    supersonic Posts: 82,708
    Smaller rotors, however, place more load into the dropouts for a given decceleration.
    GT ZASKAR CARBON TEAM

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  • nferrar
    nferrar Posts: 2,511
    Well this thread has certainly put me off Trek due to their warranty excuses, and they'd only just made it back on my 'possibilities' list after distancing themselves from Armstrong - ah well I'm sure no one at Trek's xmas bonus will be affected.

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