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    Rattling/rubbing from RD on lowest gear


    Installed a new chain on a 1×8 Tokyobike CS and sized by wrapping over the chainring and largest rear cog, adding two links to where they meet. As far as I can tell the chain is routed correctly and it shifts through all gears without issue, it's just the lowest gear that produces this rubbing sound. I've tried adjusting the limit screw, b-limit and cable tension and the sound hasn't changed. I don't know if this happened previously, the old chain was pretty rusty and I removed it as soon as I got the bike home.

    Possibilities I've considered:

    Suboptimal chainline (the BB and drivetrain are all as there were from the factory, I've only changed the chain)
    Bent hanger or derailleur cage
    Chain too short

    Anything else? I can add some more pics in the comments.

    Rattling/rubbing from RD on lowest gear
    byu/labrish inbikewrench



    by labrish

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    8 Comments

    6. Spare_Elderberry_939 on

      Couple things, that sizing method I find is pretty bad. Generally it’s better to go big cog front small cog back, and cut the chain at the point where it just long enough to keep tension the derailleur.

      Also, that gear you’re in will never work well, especially with a short cage derailleur. If the other gears are fine, just avoid that one.

    7. HOONIGAN_RB26 on

      Looks like your chain is too short for the application, also it looks like that sound is your chain rubbing on the metal alignment tab on your derailleur, spin the crank again and check your chain along the derailleur

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