Horrible evil tandem chain..

Discussion in 'Bicycle Mechanics and Repairs' started by badkitty, 21 Apr 2010.

  1. badkitty

    badkitty A Fiddler of ill repute

    I need some help folks.
    I just nearly hurled my tandem into a ditch, and then had to push the stupid thing home again. Why?

    Because the chain came off. :ohmy: Am so angry because chains are a piece of p*ss to sort normally..not something that bothers me. But this one..:angry:

    It came off in the middle chainring - the double one which connects front and back chains. So should have been a case of just whipping it back on. But the inner ring is so close to the frame that there is no room for the chain to pass unless its on the ring, which of course it's not. Everytime I tried to wind it round it just got jammed between chainring and frame.
    I tried it every which way and I cannot get it on.

    What am I missing folks? Is this a common thing with tandem chainrings, or just with mine? :wacko:
    At the moment the only way I can see to fix it is to split the chain and thread it through that way, but I've never done that in my life so am a bit scared. Do have a chain thingy tool though..

    Hopefully, I'm just being thick and someone can point out the obvious to me.

    Thanks people..
     
  2. NickM

    NickM Veteran

    I am struggling to understand "It came off in the middle chainring - the double one which connects front and back chains". Does the chain which connects front and rear chainsets run down the right hand side of the bike? Does the connecting chain use the innermost (small) chainring at the back? How many chainrings are available for gear changes at the back?

    One thing very well worth having on the drive side of tandem chainsets is this:

    http://www.sjscycles.co.uk/product-Sugino-Sugino-Autex-One-Key-release-crank-bolts-265.htm

    They get you out of the kind of jam you have described with just a 6mm Allen key.

    Another useful device, which may be applicable to your problem:

    http://www.gvtc.com/~ngear/whatis.html

    Necessary on aluminium tandem frames, I would say.
     
  3. OP
    OP
    badkitty

    badkitty A Fiddler of ill repute



    Thanks for your help nick - is most appreciated.
     
  4. NickM

    NickM Veteran

    "...would that allow me to just slaken off the cranks, and wiggle the chain ring out a bit to get the chain past?"

    Yes! It does nothing to explain why the chain is coming off, though... I think pictures might be needed to solve that. I suspect, though, that whatever device you have to maintain tension in the connecting chain is not maintaining enough tension.

    Do you Does your tandem have an eccentric bottom bracket (oooer, missus!) ?

    If you are using a hub gear, the Jump Stop may be superfluous.

    PS Ah, I think a visualisation is taking shape :angry:

    The connecting chain comes off at the stoker's chainset and gets jammed somwhere down around the stoker's bottom bracket, yes? This does sound like insufficient tension in the connecting chain. If that is something you are not equipped to sort out, a front derailleur (any old cheap one) fitted on the stoker's seat tube, with no cable connected to it but with the travel limit stops adjusted to position its cage over the chainring, may solve the problem for the time being.
     
  5. gouldina

    gouldina New Member

    Location:
    London
    Sorry badkitty, can't help at all on this but just wanted to say how much I love your sig. Made I larff.
     
  6. OP
    OP
    badkitty

    badkitty A Fiddler of ill repute

    Ta!
     
  7. summerdays

    summerdays Cycling in the sun Moderator

    Location:
    Bristol
    I have tried that method before and so far scientifically I would have to say my results would seem to indicate your conclusion was correct:biggrin:.
     
  8. OP
    OP
    badkitty

    badkitty A Fiddler of ill repute

    Ok, so this is the problem viewed from above.The chain is one the teeth nearest the camera, but then gets snarled up on the frame as the pedal's turned.



    GEDC0368.jpg







    And here is the ring from the front..


    GEDC0367.jpg

    so erm. do i need to prise off the plastic bit in the middle in order to loosen it? :angry::blush:
    And how easy is it to get it back on afterwards? :wacko:

    [​IMG][​IMG]
     
  9. OP
    OP
    badkitty

    badkitty A Fiddler of ill repute

    Bah! maybe our sample thus far hasn't been big enough though? I'm willing to give it one more try. Care to join me, Summerdays? :wacko:

    Another thought - maybe we just didn't shout loud enough, or use the right swearwords? These factors are important, you know...:angry:
     
  10. ASC1951

    ASC1951 Guru

    Location:
    Yorkshire
    Not sure about unjamming it, but you may have a chainsuck problem even if tension is correct. Is your chainring worn?
     
  11. OP
    OP
    badkitty

    badkitty A Fiddler of ill repute


    It doesn't look worn. Erm..forgive me, but what exactly is "chainsuck"? I probably need to know that. :thumbsup:

    Anyway have decided that the real problem here was that I was being a wuss and trying to avoid the obvious solution - splitting the chain.
    So I summoned all my courage and took it off.The chain is now soaking in degreaser. :smile:
    I know that's apparently the easy bit, but I'm hopeful. The metal bit's still in the chain, so it might go back on. :biggrin:
     
  12. OP
    OP
    badkitty

    badkitty A Fiddler of ill repute

    Glad you liked it!:thumbsup:
     
  13. Crackle

    Crackle Squatter

    You might want to soak the rest of the poor beast in soapy water while you're at it, judging by the BB :thumbsup:
     
  14. summerdays

    summerdays Cycling in the sun Moderator

    Location:
    Bristol
    I'm sure there will be more occasions when I try the talking/shouting at the bike in order to persuade it to work.... I'm just not convinced of a high sucess rate... still you could be right - I might not be using the correct words:biggrin:.

    OK chain suck I know a little about ... my first bike suffered very badly with it from about 4 weeks after purchase until strangely a new chain seems to have sorted most of the problem out. It's where the chain doesn't leave the front rings and going to the back and instead gets pulled up and quite often trapped between the bottom stay and the rings - jammed tight. It got to the point that I could recognise the sensation and stop pedalling immediately before it jammed solid.

    I'm not going to go into the causes of chain suck... I never managed to fully understand it.

    And if this is going to be a regular occurrence (hopefully not) can I recommend the Sram chains that have that joining link on them.. makes it really easy to undo the chain.
     
  15. OP
    OP
    badkitty

    badkitty A Fiddler of ill repute

    You think?

    That is clean! I'll have you know that when I chipped apart a big brown bike shaped boulder last week, that was what I found inside! Which is a vast improvement.
    So don't come here with yer scary one-eyed cleanliness fascism..:biggrin:::smile:

    But in case it matters, that chain is beautiful now.:biggrin:
     
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