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Canyon Ultimate AL frame – evil little crack

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  • February 27, 2017 at 8:51 pm #26829
    matthewn5

    Hello all, sad news to report. A crack has developed in the top tube on my much-loved Canyon Ultimate AL 9.0. The frameset is nearly 5 years old, but that seems young at my age 😉 It’s done about 1600km/year so that’s probably about 7000km – mainly rough London streets on the commute, but also a bit of light touring, the DunRun, winter bike etc.

    I noticed last night there was a slight bump in the top edge of the rear brake cable port, where there hadn’t been before. I looked through a magnifying glass, and the crack is already 8mm long.

    http://imageshack.com/a/img922/4549/XasRGy.jpg

    http://imageshack.com/a/img924/7840/L4sxiO.jpg

    1. What to do? I have no claim under guarantee, as I bought the frameset second hand, and I’ve used a rack etc, so the question is: ride it and see? Or attempt a repair? It looks too hard to weld – and likely to cause stress problems if it were to be welded.

    2. What to replace it with? I’ve loved its efficiency and directness. Sharp steering and a rock solid bottom bracket area. A new Canyon frame is nearly £800, post Brexit! Ideas welcome.

     

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  • March 18, 2017 at 6:49 pm #887909
    0
    beezus fufoon
    matthewn5 wrote:
    CXR94Di2 wrote:
    Get someone to TIG weld it,  it will cost only a few quid.  In the London  area there must be loads of TIG welders.

    Anyone know a good TIG welder in London?

    bikefix in lamb’s conduit street  020 7405 1218 

    March 17, 2017 at 8:06 pm #887907
    0
    matthewn5

    So Canyon have come back

    So Canyon have come back after a bit of to and fro, and said this:

    You appear to be missing part 19 (A1022937) from this diagram and this will be causing the issue you are experiencing.

    Part 19 is the little plastic insert that takes the back end of the brake cable.

    That is NOT going to a). stop the frame cracking any more, and b). heal up the existing crack. It’s like Canyon are not even reading my messages.

    https://img2.brain3.photobox.com/906617745e6aabb45950599977cccd967b4363f1bb294e4c1c2f29c9f1daab20e0061bf5.jpg

    In my view, it’s a design fail, the hole is just too big: 31mm long and 9mm wide.

    March 11, 2017 at 4:31 pm #887905
    0
    matthewn5
    CXR94Di2 wrote:
    Get someone to TIG weld it,  it will cost only a few quid.  In the London  area there must be loads of TIG welders.

    Anyone know a good TIG welder in London?

    March 7, 2017 at 8:34 am #887903
    0
    CXR94Di2

    Get someone to TIG weld it,

    Get someone to TIG weld it,  it will cost only a few quid.  In the London  area there must be loads of TIG welders.

    March 6, 2017 at 1:52 pm #887901
    0
    gunswick

    a plastic / rubber cable

    a plastic / rubber cable guide costing 50p to produce (or less) is not a stress supporting structure!

     

    that guide is highly unlikely to reduce stress on the frame that could cause a crack.  prevention of paint peeling or visual marking yes, but I don’t believe cable outers can crack frames.

    March 6, 2017 at 1:24 pm #887899
    0
    matthewn5

    Hi all,

    Hi all,

    So Canyon has responded, suggesting that if I install the missing frame cable guide, it will be fine:

    From you images it does appear that you are running this frame without one of the frame cable guides.

    Please can you send me the serial number from the is bike? It should a 14 digit code, beginning with a letter, usually M or R, on a small sticker with a qr code.

    Once I have this I could send you an exploded diagram of your bike and you could order the correct fitment for this cable to stop any unnecessary stress being applied to the frame.

     

    As someone noted above, the fitting of the brake cable has nothing to do with the crack, since the cable run is made with a full outer and there’s less than the usual compressive stress on the top tube from brake cable forces. I suppose the ‘frame cable guide’ might conceivably strengthen the opening, but if it’s like the usual plastic fitting, I doubt it.

    Comments?

    March 1, 2017 at 4:48 pm #887897
    0
    freebsd_frank
    matthewn5 wrote:
    Exactly, nothing wrong with external cables in my view! Last for ever.

    At least that big hole should have had a stiffening lip – as the front cable ‘hole’ does have.

    Agreed. If you’re going to have holes in your frame, then at least beef them up with a bit of extra material about the hole.

    But beefing up one but not the other? Makes zero sense to me. Completely half-cock.

    The other problems with concealed cables are:

    * increased difficulty running new cables.

    * water ingress. You end up with a pool of water in which your bottom bracket sits. Nice.

    The advantages are said to be:

    * more aerodynamic. Doesn’t matter a damn to those who don’t tt.

    * straighter run for cables. That’s never caused me any problems with external cables.

     

    March 1, 2017 at 4:23 pm #887895
    0
    freebsd_frank
    madcarew wrote:
    A hole in itself is not a stress riser (in fact it’s normally the opposite) but depending how the hole is made and finished it may contain stress risers.

    You’re mistaken.

    From:

    https://en.wikipedia.org/wiki/Stress_concentration

    Geometric discontinuities cause an object to experience a local increase in the intensity of a stress field. Examples of shapes that cause these concentrations are cracks, sharp corners, holes, and changes in the cross-sectional area of the object. High local stresses can cause objects to fail more quickly, so engineers must design the geometry to minimize stress concentrations.
    madcarew wrote:
    The best thing you can do is to drill a small (3-4mm hole right at the end of the crack. What this does is spread over a larger area whatever stress is causing the crack to creep . This should stop the damage getting any worse. Then filling the hole with a semi-flexible epoxy will fix cosmetic and water ingress. Clamping around the crack with a band (i.e. seat clamp) will almost certainly return the frame to virtually full strength. Or you could get a good frame builder to do a proper repair!! This certainly doesn’t have to be the end of the frame.

    Drilling a hole at the end of the crack may stop that crack propagating but the stresses present are likely to result in either a new crack propagating from the new hole or another crack propagating from the original hole.

    Whatever happens, the stresses will cause any crack to lengthen until it suddenly propagates across the entire tube when it reaches it’s critical length. Let’s hope he’s not going too fast when that happens and subsequently faceplants.

    My advice: chuck the frame and buy one made of a sensible material (not Al alloy) without any holes in it.

    You could get it welded but where is the next crack going to show up? And more importantly, are you going to notice it before it fails?

    With regards concealed cables:

    OK on a time trial bike which is going to see few miles.

    Anything else: avoid like the plague.

     

     

     

     

    February 28, 2017 at 11:35 pm #887893
    0
    madcarew

    A hole in itself is not a
    A hole in itself is not a stress riser (in fact it’s normally the opposite) but depending how the hole is made and finished it may contain stress risers. The best thing you can do is to drill a small (3-4mm hole right at the end of the crack. What this does is spread over a larger area whatever stress is causing the crack to creep . This should stop the damage getting any worse. Then filling the hole with a semi-flexible epoxy will fix cosmetic and water ingress. Clamping around the crack with a band (i.e. seat clamp) will almost certainly return the frame to virtually full strength. Or you could get a good frame builder to do a proper repair!! This certainly doesn’t have to be the end of the frame.

    February 28, 2017 at 9:52 pm #887891
    0
    matthewn5
    freebsd_frank wrote:
    matthewn5 wrote:
    Yes it’s sad about the Canyon – in retrospect having such a large hole in the top tube near the seatpost looks like a design failure…

    If you put a hole in a stressed component, then the hole will act as what’s called a “stress riser”. ie. you will get increased stresses about that hole.

    The magnitude of the stresses is difficult to model or quantify and thus are best avoided or you can end up with a frame like that pictured above where the material has failed.

    If you want a frame that might last, then avoid frames that have had holes drilled in them.

    Exactly, nothing wrong with external cables in my view! Last for ever.

    At least that big hole should have had a stiffening lip – as the front cable ‘hole’ does have.

    February 28, 2017 at 9:28 pm #887889
    0
    freebsd_frank
    matthewn5 wrote:
    Yes it’s sad about the Canyon – in retrospect having such a large hole in the top tube near the seatpost looks like a design failure…

    If you put a hole in a stressed component, then the hole will act as what’s called a “stress riser”. ie. you will get increased stresses about that hole.

    The magnitude of the stresses is difficult to model or quantify and thus are best avoided or you can end up with a frame like that pictured above where the material has failed.

    If you want a frame that might last, then avoid frames that have had holes drilled in them.

     

     

    February 28, 2017 at 4:16 pm #887887
    0
    matthewn5
    dottigirl wrote:
    I don’t know that frameset too well, but it looks like your brake cable is far, far too short. That could be placing extra stress on the frame. In fact, I wouldn’t be surprised if that’s caused the crack. 

    Probably a bit too short, but the cable outer simply goes through the frame so there’s no stress from the brake cable on that point at all. You can move it freely with a finger. I think it’s the flexy ‘VCLS’ seatpost that’s putting stress on the thin top tube at that point.

    The large hole so close to the junction is something I’ve seen cause cracking in other frames – e.g. the problem with some Whyte frames reported here last year.

    February 28, 2017 at 10:43 am #887885
    0
    dottigirl

    I don’t know that frameset

    I don’t know that frameset too well, but it looks like your brake cable is far, far too short. That could be placing extra stress on the frame. In fact, I wouldn’t be surprised if that’s caused the crack. 

    February 28, 2017 at 7:55 am #887883
    0
    matthewn5

    barbarus wrote:

    barbarus wrote:
    I’d love to hear your opinions on the cinelli, Matthew, I’ve been umming and ahhing about one for a while now. Sorry to hear about your canyon!

    OK, I’ll report back in due course.

    Yes it’s sad about the Canyon – in retrospect having such a large hole in the top tube near the seatpost looks like a design failure…

    February 27, 2017 at 11:12 pm #887881
    0
    barbarus

    I’d love to hear your
    I’d love to hear your opinions on the cinelli, Matthew, I’ve been umming and ahhing about one for a while now. Sorry to hear about your canyon!

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