Ultegra Di2 front mech failure

Discussion in 'Bicycle Mechanics and Repairs' started by JhnBssll, 12 Jan 2019.

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  1. JhnBssll

    JhnBssll Über Member

    Location:
    Suffolk
    I was greeted by a loud bang on a front upshift three miles in to this morning's club ride. It completed the shift leaving me in the big ring but with significant rubbing and the noise that goes with it. I figured the mech had moved slightly due to a loose bolt or similar so shifted back down and continued to the cafe stop. On inspection it was immediately apparent it was terminal and the mech was toast so I left my comrades at the cafe and went the direct way home.

    The outer linkage has failed at the top pivot, there's a chunk missing allowing the mech to flap around. Fortunately spring tension kept it steady allowing me to get home... It's only done about 200 miles and was properly installed and adjusted, most irritating! Ive started the warranty return process, hopefully I'll get a replacement relatively quickly :okay:

    20190112_114633.jpg 20190112_114713.jpg
     
  2. It’s not an unusual failure to see. Normally it’s down to poor handling of the bike during shipping, or it takes an unseen knock somewhere ( bike rack at work, or on a train ).
     
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  3. Cycleops

    Cycleops Guru

    Location:
    Accra, Ghana
    Sorry. Maybe those old fashioned cable operated things aren't so bad after all ^_^.
     
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  4. Blue Hills

    Blue Hills ^

    Location:
    London
    Isn't it quite hard to bash a front mech to that extent?

    Am sure many of us have had experiences with rear mechs being knocked inwards a bit and if you aren't careful to check after such events/bend them or the hanger back, had them "interfere" with the spokes.

    This one does seem to be a clear warranty job.
     
    Last edited: 12 Jan 2019
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  5. dave r

    dave r Dunking Diddy Dave Pedalling Pensioner

    Location:
    Holbrooks Coventry
    I've not seen that happen before.
     
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  6. SkipdiverJohn

    SkipdiverJohn Über Member

    Location:
    London
    Now now, that's not really what the OP wants to hear - even if it is true. :rolleyes: I'd be mighty hacked off at a failure like that considering how expensive that stuff is.
     
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  7. OP
    OP
    JhnBssll

    JhnBssll Über Member

    Location:
    Suffolk
    The OP is quite thick skinned and suspects he may have brought this on himself by preaching of Di2's reliability recently :shy:

    That's my opinion too, I've taken it off and cleaned it up and there are no other marks on it. I've had a confirmation email back from CRC so they've received the warranty form, hopefully I'll hear back from them by mid week and get a replacement on its way.
     
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  8. Smokin Joe

    Smokin Joe Legendary Member

    The failure is nothing to do with the mech being cable or electronic. It is a physical break in the material.
     
  9. Cycleops

    Cycleops Guru

    Location:
    Accra, Ghana
    While we're on the subject what material is it? Looks like some sort of plastic.
     
  10. Smokin Joe

    Smokin Joe Legendary Member

    I'd say Aluminium, but the OP will confirm one way or the other.
     
  11. OP
    OP
    JhnBssll

    JhnBssll Über Member

    Location:
    Suffolk
    It appears to be injection moulded carbon reinforced plastic.

    20190112_182836.jpg 20190112_182848.jpg
     
  12. Blue Hills

    Blue Hills ^

    Location:
    London
    could it perhaps have done a very unwise shift attempt?

    Declaration of interest and since the nice OP has said they are thick skinned - I can't really see the point of these things for anything but very high end Pro or potential pro use. I recently bought 100 high quality stainless gear cables for not much over £50 and although I admit that because of high clamp-angle stresses on gear cables (not brake cables) these things need to be watched for fraying I still think it the best solution for the vast majority of cycling. Also, I have never wrecked a front mech. Worn out yes, not wrecked.
    Surely only a matter of time before cables are thought o so passe on brakes and someone comes up with electronic braking, linked to GPS and a global map which senses the gradient and knows how much, whatever you think, you really really want to/need to brake?
     
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  13. Smokin Joe

    Smokin Joe Legendary Member

    The point is that some people like it and are prepared to pay for it. There are so many bits of technology we all daily use that could be described as pointless by anyone who didn't want it. My late BiL used to say that about computers and mobiles (Mind you, he was a miserable old B).
     
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  14. fossyant

    fossyant Ride It Like You Stole It!

    Location:
    South Manchester
    Silly place to save weight on a part. Never had any front mech fall apart. That's a bad choice of material, and expensive.
     
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  15. Reynard

    Reynard Veteran

    Location:
    Cambridgeshire, UK
    When CFRP works right (and the fibre type / lay-up is correctly designed for the task in hand), it's bang on. If it's injection moulded chopped strand, it should be pretty strong in all directions of load.

    Looking at the failure, it seems to me that there may well have been an air bubble along some of the fibres - which points to a manufacturing issue. You *really* don't want air bubbles in composite structures...
     
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