New Crankset and BB = Bad Chaninline

Discussion in 'Cycling Equipment' started by Pep, Jan 22, 2003.

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  1. Pep

    Pep Guest

    RBT:

    I replaced the old LX crankset and tapered BB with a new LX hollowtech and splined BB. I replaced
    the BB with the same size as the original tapered model - 73x113. Now my chainline is completely off
    - in fact, the smallest chainring actually bottoms out on the BB shell if I torque the drive-side
    crankarm down all the way. I could try a 73x118, but I'm not convinced that the additional 2.5mm on
    the drive side will be sufficient to give me the correct chainline.

    Please advise.

    Thanks, Pep
     
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  2. Pep

    Pep Guest

    Did a little more digging myself...

    The new LX crankset M572 requires an ES-51 BB which incorporates a 121mm spindle.

    "Pep" <[email protected]> wrote in message news:[email protected]...
    > Hmmm...no paper tucked in my box.
    >
    > Is the additional spindle length distributed equally on the drive and non-drive sides? In other
    > words will I only gain an additional 2.5mm of spindle length on the drive-side when moving from
    > 113 to 118?
    >
    > Pep
    >
    > "A Muzi" <[email protected]> wrote in message news:[email protected]...
    > > "Pep" <[email protected]> wrote in message news:[email protected]...
    > > > RBT:
    > > >
    > > > I replaced the old LX crankset and tapered BB with a new LX hollowtech
    > and
    > > > splined BB. I replaced the BB with the same size as the original
    > tapered
    > > > model - 73x113. Now my chainline is completely off - in fact, the
    > > smallest
    > > > chainring actually bottoms out on the BB shell if I torque the
    > drive-side
    > > > crankarm down all the way. I could try a 73x118, but I'm not
    convinced
    > > that
    > > > the additional 2.5mm on the drive side will be sufficient to give me
    the
    > > > correct chainline.
    > >
    > > The paper that's tucked into the box with a new LX crank (FC-M571)
    > specifies
    > > a BB-ES-70E which should be 68x113, alternatley 73x118.
    > >
    > > Since the basic form of the arm is radically different from one crank to another (the position
    > > of the middle ring in relation to the end of the spindle) you can't make any assumptions about
    > > BB spindle length across
    > crank
    > > models, even when Shimano has re-used the "LX" designation for a
    > completely
    > > different product.
    > >
    > > And the relationship from the middle ring to the end of the spindle is
    not
    > > at all identical from square to spline spindles. You're imputing more
    > order
    > > than exists!
    > >
    > > Is there something unusual about your frame that indicates less
    clearance
    > at
    > > the chainstay than normal? Shimano's tech data is seldom wrong in this area.
    > >
    > > --
    > > Andrew Muzi http://www.yellowjersey.org Open every day since 1 April 1971
    > >
    >
     
  3. MOGorospe

    MOGorospe New Member

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    I am having the same problem. I purchased the Shimano Octalink, LX crankset to replace my original ones. As suggested, I got BB at it's original size..73X113. It's not working out. Even with the 118, a spacer had to placed and it's still rubbing on the derailleur.
    My question is, did the 121mm work for you. Because from the looks of it, I have to get the 121mm to make it work. My bike shop is suggesting to keep the crankset, and replace my entire bike component to 9-speed, which I don't want to do. I want to remain at 8 speed.
    Any suggestions..
    Thanks..
    MOGorospe
     
  4. A Muzi

    A Muzi Guest

    > Pep wrote:
    > > RBT: I replaced the old LX crankset and tapered BB with a new LX hollowtech and splined BB. I
    > > replaced the BB with the same size as the original tapered model - 73x113. Now my chainline is
    > > completely off
    > > - in fact, the smallest chainring actually bottoms out on the BB shell if I torque the
    > > drive-side crankarm down all the way. I could try a 73x118, but I'm not convinced that the
    > > additional 2.5mm on the drive side will be sufficient to give me the correct chainline.

    "MOGorospe" <[email protected]> wrote in message
    news:[email protected]...
    > I am having the same problem. I purchased the Shimano Octalink, LX crankset to replace my original
    > ones. As suggested, I got BB at it's original size..73X113. It's not working out. Even with the
    > 118, a spacer had to placed and it's still rubbing on the derailleur. My question is, did the
    > 121mm work for you. Because from the looks of it, I have to get the 121mm to make it work. My bike
    > shop is suggesting to keep the crankset, and replace my entire bike component to 9-speed, which I
    > don't want to do. I want to remain at 8 speed.

    I am confused by these frequent crank/BB posts. In my experience, Shimano's printed directions in
    the crank box are correct nearly always, unless there's some drastically weird frame involved . In
    the case of a FC-M571, Shimano suggests a 113 for a 47.5 and a 118 for the alternate fat-tube 50mm
    chainline. I have installed a few ( certainly not a lot of them here, but some) of these cranks this
    year without incident using the Shimano specified BB lengths. As a matter of fact, we hardly ever
    change a BB length once its installed according to the spec. We couldn't get anything done in a day
    if we had to intuit and experiment with that sort of thing. So I wonder what's up .Did your
    chainring hit the chainstay? When you say "it's still rubbing on the derailleur" do you mean the
    chain drags the cage? Did you unscrew the inner limit? Is your frame som unusual item?

    And when your advisor suggests "my entire bike component to 9-speed" what the heck would that do to
    move the crank arm on the spindle?? I don't understand that at all.

    --
    Andrew Muzi http://www.yellowjersey.org Open every day since 1 April 1971
     
  5. Gregr

    Gregr Guest

    On 28 May 2003 15:30:06 +0950, MOGorospe <[email protected]> wrote:

    >I am having the same problem. I purchased the Shimano Octalink, LX crankset to replace my original
    >ones. As suggested, I got BB at it's original size..73X113. It's not working out. Even with the
    >118, a spacer had to placed and it's still rubbing on the derailleur. My question is, did the 121mm
    >work for you. Because from the looks of it, I have to get the 121mm to make it work. My bike shop
    >is suggesting to keep the crankset, and replace my entire bike component to 9-speed, which I don't
    >want to do. I want to remain at 8 speed. Any suggestions.. Thanks.. MOGorospe

    The newer LX splined cranks need a longer BB than the earlier splined models. Why you ask? Well
    shimano figures there was not enough difference between the LX and XT model, people were using the
    LX crank with a XT BB (lighter, better bearings) and getting the same performance for much less $$.

    Now with the LX you need to buy the longer LX BB (not interchangeable with XT because the XT is much
    shorter). And if you want to upgrade, you cant just buy cranks....

    G
     
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