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  1. #1
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    Crank and BB, chain line

    OK so I went from 42/32/22 to 48/38/28 on the crank, 38 and 28 hit the chain stay, I hammer it in, tons of room. I have a UN-26 BB 110mm in length 68mm wide shell. I am having a very hard time finding what total length spindle came with that bike. I got some # off Sheldon Browns site, I attached an image, highlighted mine. I was thinking maybe it could have been 113mm or 118mm. Will my chainline be messed up because the frame used to be 7spd all LX components. I am going to a 8 or 9 speed setup.

    All I bought was the frame that came with a headset and the fork that came with it.
    The fork I have is newer, and higher, puts the frame at different angle but its alright.
    Attached Thumbnails Attached Thumbnails Crank and BB, chain line-lx-bb.jpg  


  2. #2
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    It doesn't matter what the original bb size was because that is dependent on the particular crankset being used, but I'd be a be a little more concerned about the mangled chainstay than your chainline at this point.

  3. #3
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    Too late now, its an old frame from 1994 and its cromo steel, I hammered it good to save $16 on a new BB or crank sprockets, I tried putting on a 31.8mm clamp FD on a 28.1mm tube with 2 pieces of cut pvc pipe which worked good for the clamp tightness, however I cant adjust it at all for the 28 ring, doesnt even get close. I think if I were to buy a 68 x 122.5mm it will bring the smallest ring out more wouldnt it?

    I dont know what else to try, I dont know if new 8/9 spd cranks are different then old 7spd cranks. It could be my FD, maybe I need to buy a 28.6mm clamp FD. I've tried shimmy'ing the 31.8 so the face is at the seat tube and a shim on the 2o'clock side.

  4. #4
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    Yeah I dont know, I think I line up the inside part of the FD bracket with the crank gear with a tad of an offset inwardly, I will have to youtube it and see, the distance seems right but maybe my smallest crank gear maybe off. The way I have it now, I reduced my shims in size to about the size of a nickel, placed them at 2 o'clock to be sure the bracket on the gear side (6 oclock) is flush to the seat post. I've eyeballed it and it seems correct, I think my limit screws are an issue, I noticed that with my 48T gear.

  5. #5
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    You might try bashing it in a little with a hammer

  6. #6
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    Whats wrong with hammering the chainstay tube for a little clearence?

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