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chain brushes off front derailleur

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  • 30-03-2006 9:09am
    #1
    Raam
    Registered Users Posts: 14,317 ✭✭✭✭


    maintenance question here:

    If I am in my middle (or even largest) front bash ring, and then shift to the smaller cogs at the back, the chain starts to rub off a bit of the front derailleur (the right hand part), if I shift to the larger cogs, then it's OK. Obviously, I have to make a slight adjustment somewhere to stop this, however, in the past I've managed to mess it up a bit, so where should I start? The tensioning screws maybe? I'd like to handle this myself rather than bringing it to a bike shop.
    any ideas?

    cheers

    P


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    #2
    randomname2005
    Registered Users Posts: 1,932 ✭✭✭randomname2005


    http://www.utahmountainbiking.com/fix/index.htm
    and
    http://www.parktool.com/repair/readhowto.asp?id=75
    might be of use to you.
    You might just need a slight adjustment of your barrel adjuster on your gear shifter.
    R


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    #3
    rubadub
    Registered Users Posts: 32,373 ✭✭✭✭rubadub


    If you are on the middle at the front you should not be on the smallest cogs on the back. I used to do the same thing and my mate showed me the excess wear on the back cogs and the chain was in bits too from it.


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    #4
    daymobrew
    Registered Users Posts: 6,493 ✭✭✭daymobrew


    You shouldn't be shifting to the smaller cogs - it causes the chain to bend a bit and that's not good. Your bike manual should mention this.
    From the last paragraph of How To Shift Your Bicycle's Gears
    Try to avoid the gears that make the chain cross over at an extreme angle. These "criss-cross" gears are bad for the chain and sprockets. Especially bad is to combine the inside (small) front sprocket with the outside (small) rear sprocket. This noisy, inefficient gear causes the chain to wear out prematurely.


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    #5
    Raam
    Registered Users Posts: 14,317 ✭✭✭✭Raam


    thanks for the replies/links guys.

    I'm aware that the chain should not be crossed (been warned about that loads :) ). That said I probably was chain-crossing a bit, although I wasn't in the smallest of the rear rings. I'd still like to get rid of the noise.

    I'll see if I can sort it this eve

    P


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    #6
    Mucco
    Registered Users Posts: 714 ✭✭✭Mucco


    rubadub wrote:
    If you are on the middle at the front you should not be on the smallest cogs on the back. I used to do the same thing and my mate showed me the excess wear on the back cogs and the chain was in bits too from it.

    I differ from this view. When in the middle chain ring, it should be possible to use both the smallest and the largest cog without chain rub.
    In your case, it sounds like your cable has stretched a little. The easiest way to fix this is to use the adjusting screw on you gear lever. Just screw it out a couple of turns, then pedal to test, screw out a bit more etc... If you're already at maximum, you'll probably have to adjust the cable which is a bit more tedious. Don't forget to keep your cables clean and oiled to allow them to run smoothly through the outers.

    M


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    #7
    wideangle
    Registered Users Posts: 925 ✭✭✭wideangle


    What you are doing puts the chain at an angle going from largest ring at front to the smallest at the back.The best thing to do is not to use the last two gears at the back when on the largest ring on the front.If you continue you will wear the chain and the cogs and they will need replacing.


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    #8
    John_C
    Registered Users Posts: 1,029 ✭✭✭John_C


    wideangle wrote:
    What you are doing puts the chain at an angle going from largest ring at front to the smallest at the back.
    Am I missing something here? Is that not a sensable combination for going downhill, i.e. your most difficuly gear?


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    #9
    Raam
    Registered Users Posts: 14,317 ✭✭✭✭Raam


    the rule, as far as I am aware, is: avoid large to large and avoid small to small.

    With regard to my original post, last night I adjusted the angle of the deraileur. I could see that it wasn't quite parrallel with the chain rings. I didn't notice the problem on my cycle this morning.

    sorted

    P


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    #10
    Alkers
    Registered Users Posts: 6,811 ✭✭✭Alkers


    wideangle wrote:
    What you are doing puts the chain at an angle going from largest ring at front to the smallest at the back.The best thing to do is not to use the last two gears at the back when on the largest ring on the front.If you continue you will wear the chain and the cogs and they will need replacing.
    Largest at the front to smallest at the back is fine, the chain won't be at much of an angle as it's in the outermost cog front and back. The problem is when using the biggest with the biggest or the smallest with the smallest. THis shouldn't cause problems as similiar ratios should be availible by using a different gear.


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