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Rear Derailer Placement: Replacing Chain

GipfishGipfish Posts: 8
edited March 2016 in Workshop
I'm trying to replace a chain on a road bike. The lower pulley on the rear derailer is sitting so far forward of the upper pulley that the chain won't even catch on the upper pulley. How do I fix this? I did some extensive googling, but I haven't come across any images where the rear derailer is positioned the way this one is.

Posts

  • BikeRadarAdminBikeRadarAdmin Posts: 909
    Struggling to picture this...

    Have you got an image you can show us?

    Sounds like it may be a busted derailleur but I could be wrong!
    BikeRadar Communities Manager
  • GipfishGipfish Posts: 8
    I have a picture. What is the best way to post it?
  • keef66keef66 Posts: 13,123
    Has the rear derailleur been taken off the bike or is it where it was before the old chain came off?

    Your description makes it sound like the chain's miles too short, but even then the chain would still contact the upper jockey wheel.

    Upload the picture to an image hosting website such as Flickr then paste in the URL. Instructions in a sticky at the top of the forum
  • GipfishGipfish Posts: 8
    Never mind. I found the FAQs. Here is a picture of the issue.
    IMG_20160330_163349664_zpswvlzofad.jpg
  • GipfishGipfish Posts: 8
    IMG_20160330_163408471_zpsjk1r9gp6.jpg
  • GipfishGipfish Posts: 8
    From my understanding, that lower pulley should be directly below the upper one, not three inches out in front of it. The chain won't catch on the upper one when I thread it through. I have never done this before, so I need some guidance.
  • GipfishGipfish Posts: 8
    As for how it was before, I honestly have no clue. This is my husband's bike. He took off the chain to clean it, broke the chain (it was old and rusty anyway), bought a new chain, got frustrated with this derailer issue, and gave up. So I have been watching chain replacement videos and trying to fix it for him.
  • keef66keef66 Posts: 13,123
    The derailleur should have spring tension so that it's pulling the cage backwards, ie to the left in your pic. That's what keeps the chain tight. Without the chain the mech should fold back on it's self, so something's wrong there.

    Looks to me as if the cage has rotated clockwise so the spring's no longer effective. Can you turn it 360 deg anticlockwise so you feel spring tension again? You might have to take it off the bike to do it.

    Either that or the spring's broken and you'd need a new mech. A Sora mech is pretty cheap.
  • GipfishGipfish Posts: 8
    Thank you, I'll give it a shot and let you know how it goes.
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