Sheared Bolt

swj1
swj1 Posts: 70
edited July 2016 in Workshop
Hi All,
I hope I can pick your collective brains, I have a Canyon AeRoad 7.0 Di2 which I have owned since August last year. Whilst out last a few weeks a go my seat lowered as I rode uphill. I went to raise it back up and noticed that one of the bolts seemed to have broken through the clamp. I have never tightened over the recommend 6n using a torque wrench so I am not sure how this has happened but not only that when I loosened the opposite bolt it sheared off leaving half off it in the frame.

I took it to by lbs to see if they could get out the sheared bolt, they thought they could but have not been able to.

I am not sure what would have caused this, I am not the lightest at 90kg but would not have expected this? I have tried to contact Canyon but they have a message on the phones advising they are very busy which I guess is to be expected this time of year....

Any advice would be gratefully received

Comments

  • Matthewfalle
    Matthewfalle Posts: 17,380
    Easy out, drill out, cut a flat in and try to unscrew or take to a decent FrameMaker/shop.
    Postby team47b » Sun Jun 28, 2015 11:53 am

    De Sisti wrote:
    This is one of the silliest threads I've come across. :lol:

    Recognition at last Matthew, well done!, a justified honour :D
    smithy21 wrote:

    He's right you know.
  • lapavoni10
    lapavoni10 Posts: 146
    I would have thought a stud extractor would have done the trick? Maybe worth locating an engineering shop near you if you are nervous about drilling :)
  • frisbee
    frisbee Posts: 691
    Since snapping an easyout, applying very little force, I've not been a fan of them.

    Molegrips or cut a slot or try and loosen it using blows with chisel or punch.
  • sungod
    sungod Posts: 16,558
    blows with a chisel or punch? on this seatpost clamp?

    http://www.canyon.com/i/bikes/zoom/2014 ... ckside.jpg

    really wouldn't advise that!

    op - you wrote "broken through the clamp" are you saying the clamp broke as well as the bolt? or just the bolt snapped?

    i assume the bolts go into threaded inserts anchored in the frame, so access will only be from the entry hole

    presumably there's not enough sticking out to get a grip on or cut a slot, if you've got a dremel/similar, you can drill a hole in the end of the bolt and then use a screw extractor to remove it, if you're not comfy doing this find an lbs that is, might be an idea to apply some plusgas to try and loosen the bolt first

    is 6Nm the recommended torque or the maximum torque? to reduce risk in future i'd use some carbon assembly paste on the tube to increase friction and then only tighten the clamp enough to grip, also put some antiseize on the bolts before inserting
    my bike - faster than god's and twice as shiny
  • frisbee
    frisbee Posts: 691
    sungod wrote:
    blows with a chisel or punch? on this seatpost clamp?

    http://www.canyon.com/i/bikes/zoom/2014 ... ckside.jpg

    really wouldn't advise that!

    Why not? You just give it a few gentle taps in an anti-clockwise direction to get it moving.

    However if its already been attacked by the bikeshop its probably too stuck to work.
  • balthazar
    balthazar Posts: 1,565
    That's a horrific design for a seat clamp..! Anyway- it sounds very much like this was a fatigue failure, like nearly everything else in bicycles that fails. That won't have been caused by over tightening, rather poor design and material selection, and simply bad luck.

    As others have said, ez out or similar will probably do it. If the bolt failed because of fatigue, the remaining piece is unlikely to be seized in the frame: it may well come out easily.
  • proto
    proto Posts: 1,483
    frisbee wrote:
    Since snapping an easyout, applying very little force, I've not been a fan of them.

    Molegrips or cut a slot or try and loosen it using blows with chisel or punch.


    Yep, that's what I'd do.

    Try a slender centre punch, and tap it anti-clockwise. In theory there's nothing holding it in so should rotate easily. Another option is to use a small left hand drill (yes, such things do exist) and if there's a flat enough surface to drill onto, then try and drill it out (obviously you'll need a pistol grip type tool that goes anticlockwise too!). You'll either successfully drill it out, or more likely, the drilling action will unscrew the thread and drive it out of the threaded hole.

    In my experience 'Easyout' extractors are less than useless.
  • swj1
    swj1 Posts: 70
    Thanks for all the advice guys, I have sent Canyon some pics so I will see what they say.
  • wave397
    wave397 Posts: 1
    Hi swj1,

    A read your post and unfortunately the same thing happened to me this weekend!
    What was your end result with this issue with Canyon?
    Guidance on this issue would be greatly appreciated.

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