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  1. #1
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    Bonking ... not feelin' well Replaced my 32T middle ring with a 44t outer ring, but it won't go on there. Help!


    I don't get this. I have a crankset that I plan to use the middle ring on. Problem is that the 32T middle ring is too small, but my 44T outer ring is the right size. However, when I put my 44T ring in the middle ring's position on the crank, it doesn't fit. Why? Both the outer and middle rings are supposed to have a BCD of 104mm. The inner ring has a BCD of 64mm.

    Shimano Deore M510 Crankset (4-arm) - 104/64mm BCD
    Last edited by barber; 04-24-2007 at 04:24 AM.

  2. #2
    Nat
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    Quote Originally Posted by barber

    I don't get this. I have a crankset that I plan to use the middle ring on. Problem is that the 32T middle ring is too small, but my 44T outer ring is the right size. However, when I put my 44T ring in the middle ring's position on the crank, it doesn't fit. Why? Both the outer and middle rings are supposed to have a BCD of 104mm. The inner ring has a BCD of 64mm.

    Shimano Deore M510 Crankset - 104/64mm BCD
    In what way does it not fit? Are the bolts too short? Do the bolts not line up with the holes?

  3. #3
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    A 44t ring in the middle position of the crank spider will probably interfere with the chain stay.

  4. #4
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    Quote Originally Posted by Nat
    In what way does it not fit? Are the bolts too short? Do the bolts not line up with the holes?

    The outer and middle rings use the same holes, and the bolts are the same also. Bolts are the right size as well. The outer chainring does not fit in the middle chainring space because of the chainring itself, not the holes or bolts. I don't know how else to describe it. The holes & bolts are fine.
    1. Outer ring in the outer position - it lines up perfectly, meshes perfectly, fits perfectly...
    2. Middle ring in the middle position - it lines up perfectly, meshes perfectly, fits perfectly...
    3. Outer ring in middle position - it does not fit. The area where the chainring touches the crankarm (where the holes are); this area is where I am not getting the chainring to lie flat on the crankarm. It does not mesh well together.

  5. #5
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    Quote Originally Posted by itsdoable
    A 44t ring in the middle position of the crank spider will probably interfere with the chain stay.

    I already check that. I have plently of chainstay clearance, so this isn't an issue.

  6. #6
    CB2
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    Maybe you need to grind some material of the ring to make it fit?

  7. #7
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    alternatively, if you are using a cassette wheel, you can just run spacers to put your cog in line with the large chainring in it's regular position on the crankarm (basically run your cog as close as possible to the cassette lockring to get a decent chainline).

  8. #8
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    Are you putting it on the inside or the outside of the arms?

  9. #9
    Nightriding rules SuperModerator
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    Quote Originally Posted by dumbaSS
    Are you putting it on the inside or the outside of the arms?
    he is putting it (well trying) on the inside (middle ring position)

    I suppose that you need to dremel or file some material off...sometimes chainrings (like shimano in this case) are like that..

  10. #10
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    Quote Originally Posted by barber

    I don't get this. I have a crankset that I plan to use the middle ring on. Problem is that the 32T middle ring is too small, but my 44T outer ring is the right size. However, when I put my 44T ring in the middle ring's position on the crank, it doesn't fit. Why? Both the outer and middle rings are supposed to have a BCD of 104mm. The inner ring has a BCD of 64mm.

    Shimano Deore M510 Crankset (4-arm) - 104/64mm BCD
    The "shoulder" of the crankarm is smaller (higher up towards the hole, on the inside than the outside. The ring will fit, but you'll need to file down either the ring or the ramps on the spider to make it work. I'd recommend option B.

    My fixie currently has a 104 bcd 44 t Salsa ring on the inside, and I had to file ~2mm off each shoulder to make it fit. A 10 minute job.

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