chain runs against the chain on the derailleur

yadnom1973
yadnom1973 Posts: 45
edited June 2015 in Road beginners
I have replaced the cable on my back derailleurs. I have watched a bunch of how to videos and have been setting the lower and higher limit adjuster screws and the B tension screw. Everything seemed fine but then when I drop into the smallest cog on the front and then on the back the chain runs against the chain on the derailleur. It’s hard to explain so I made this little vid: https://youtu.be/5iL2A9HZnH8
I wanted to put the video in the post but cant see how.
I cant see how to stop this? I tighten up the cable and then it won’t drop at all into the higher gears and if I loosen it to the point where it will drop into the smallest cog this happens. I have tried adjusting the B tension screw but it seems to make little difference and non of the videos talk about this happening.
Can anyone help?

Comments

  • Ouija
    Ouija Posts: 1,386
    edited June 2015
    Chains not short enough. It should be just long enough to stop the derailleur completely folding up like that.
  • yadnom1973
    yadnom1973 Posts: 45
    Too short? Yoy mean this is not a problem with adjustments, I need a new chain? I've been riding this bike for +2 years, I guess I never went into the very top 2 gears.
  • keef66
    keef66 Posts: 13,123
    [url=http://www.bikeradar.com/forums/viewtopic.php?p=19623003#p19623003]Ouija[/url] wrote:
    Chains too short. It should be just long enough to stop the derailleur completely folding up like that.

    I think you mean the chain's too long as it is. You need to remove one, possibly two links.

    Have you replaced the chain or any other transmission components? just replacing the gear cable wouldn't make this suddenly happen.
  • yadnom1973
    yadnom1973 Posts: 45
    Too long, that makes sence. I think it's just old. I have the tool though so I'll give it a go, thanks for the advice guys.
  • lesfirth
    lesfirth Posts: 1,382
    Your chain is certainly too long.
  • ForumNewbie
    ForumNewbie Posts: 1,664
    [url=http://www.bikeradar.com/forums/viewtopic.php?p=19623081#p19623081]yadnom1973[/url] wrote:
    Too long, that makes sence. I think it's just old. I have the tool though so I'll give it a go, thanks for the advice guys.
    Yes, chain is too long, but you also may need new chain if it's old as you say. But at least you can shorten that one first to establish the correct length - there are lots of instructions online as to how you can calculate the right chain length for your bike.
  • rafletcher
    rafletcher Posts: 1,235
    And then, after you fit the new chain, it'll maybe start to skip gears, as the cassette teeth may be worn too, and possibly chainring teeth as well. :)
  • dj58
    dj58 Posts: 2,224
    ^Yes, if you have been using that chain for 2yrs and have not been checking it for wear, then depending on your mileage you may need a new cassette as well.
  • cattytown
    cattytown Posts: 647
    Before shortening the chain, I would also check length in big chainring/sprocket combination too...

    Sounds most like a worn chain that has stretched a little.

    Paul.
    Giant Defy 2
    Large bloke getting smaller :-)

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