Drivetrain problem- Mtbr.com
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  1. #1
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    Drivetrain problem

    Rencently I use freehub and I use single freewheel before which now my frame and brake problem is solved but now the drivetrain have problem. I use deore XT cog and 7 speed chain.

    My chain sometimes got derailed when I hammer or overspin. As usual the chain have tight spot like get ovaled chainring which is make my pedaling not smooth.

    The questions are:
    1. I wonder if I can solve my tight spot problem using ocalink BB and crankset?
    2. If I use singlespeed cog and singlespeed chain, would it solve the derailed problem?

  2. #2
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    Quote Originally Posted by jackspade
    Rencently I use freehub and I use single freewheel before which now my frame and brake problem is solved but now the drivetrain have problem. I use deore XT cog and 7 speed chain.

    My chain sometimes got derailed when I hammer or overspin. As usual the chain have tight spot like get ovaled chainring which is make my pedaling not smooth.

    The questions are:
    1. I wonder if I can solve my tight spot problem using ocalink BB and crankset?
    2. If I use singlespeed cog and singlespeed chain, would it solve the derailed problem?
    A lot of crank/ chainring combinations result in a tight spot. Before you buy a new crank, try centering your chainring on the crank. Usually there is a little play in the positioning of the chainring; loosen the chainring bolts and try to better center the chainring.
    #2 singlespeed cogs aka bmx cogs do hold a chain better and certainly will make things better, but a good chainline and mitigating the tight spot will do more, unless there is some other issue with your chain, an 1/8" chain won't make any difference. There are also other possibilities; i.e. are you using a tensioner?
    Just one more rep and I get the toaster!

  3. #3
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    Can you provide pictures? Could you use a chain guide or bashguard and chain keeper combo? Is your chain new?
    My motorcycle runs on infant blood

  4. #4
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    Like Brad said - try centering the chainring first - slacken off the bolts and then "nip" them enough the hold the chainring firmly but still allow it to be moved if it is tapped with a piece of wood or a soft hammer. Then spin the cranks to find the tightest spot and when you do, tap the chainring backwards - spin the cranks again to see if there is an improvement and repeat this until you get as good a result as possible. Then tighten the bolts completely.

    A deep tooth sprocket will be better than one from a cassette and if you're not using sufficient chain tension the derailing issue might be due to sideways movement of the bottom or top run of the chain, especially over rough ground. A 3/32" singlespeed chain might be better in this respect than a multispeed chain, as the chain for a geared system is designed to have sideways flexability (it has to, in order to change sprockets or chainrings) whereas a singlespeed chain doesn't have to.

    Try something like a KMC Z610-HX and see if that cures your problems.

  5. #5
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    Thanks for the replies.

    I do use bashguard and I don't use tensioner.
    Also my chain is new and I don't know if I use specific 7 speed chain because it's only written 1/2" x 3/32" x116L.

    About the octalink I read somewhere that this is better than square tapper (which I currently use now) for the oval problem but I'll try to center the chainring first.

  6. #6
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    if there is play, screws dont hold in place. imagine the power when you kick the pedals ... its more about chainline.

  7. #7
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    I think I'll try to move the cog between spacers.

    My naked eyes says it straight but I think the chain knows it better LOL.

  8. #8
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    Quote Originally Posted by Andy R
    Like Brad said - try centering the chainring first - slacken off the bolts and then "nip" them enough the hold the chainring firmly but still allow it to be moved if it is tapped with a piece of wood or a soft hammer. Then spin the cranks to find the tightest spot and when you do, tap the chainring backwards - spin the cranks again to see if there is an improvement and repeat this until you get as good a result as possible. Then tighten the bolts completely.
    Another thing you may want to try is to rotate the chainring on the crank. While there is a tab showing the correct orientation, it serves no purpose with a single speed.
    Just one more rep and I get the toaster!

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