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2011 TREK Marlin BBS02 Build: Chainring issues! Please help!

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    2011 TREK Marlin BBS02 Build: Chainring issues! Please help!

    HI Guys, Long time lurker first time poster.

    I have taken the plunge on a BBS02 for my 2011 Trek Marlin. The install went fine, but upon test ride, it has been victim of chain-suck and is not mating the chain to the Bafang chain ring so well. I did buy a gauge and tested it, the chain was very stretched. I have since purchased a new one and it still seems to be binding up on the sprocket. Like the sprocket teeth are too tall or too wide or spaced too far apart. Any suggestions? I have contacted the ebay seller about this and they seem to think it is my rear sprockets that need replacing. Any ideas? I am stumped and cant be the first person with this issue...


    The bike:

    Chain line / alignment looks decent:

    old chain:

    sample chainsuck:

    new chain, better but still issues:

    freewheel for reference:

    any ideas?

    It looks to me like the chainring is wider than the chain. Is your new chain a 7 or 8 speed chain and not 9 or 10 speed?
    I'd measure the chainring width at the base of the teeth with a micrometer or good caliper and see if the teeth are under 3/32” in width. If it is a narrow-wide ring you’ll need to check width of 2 consecutive teeth.


      Just to follow up with this, the seller (ebay) gave me a sprocket that was not designed for this size chain (or really a typical bicycle chain). Got a new Luna CNC sprocket and all is well. I ended up buying another kit from the seller and the sprocket was different from this. very strange.


        Just out of curiosity, can you tell us what kind of sprocket they sent you?...small motorcycle type, BMX, etc.?


          I have only seen issues like that when trying to use some 'single speed' chains on a 'narrow wide' that can take the latest 11 and maybe 12 speed chains.