68x127 bottom bracket & crank question

Discussion in 'Cycling Equipment' started by Kelling, May 20, 2003.

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  1. Kelling

    Kelling Guest

    Hi!

    Please help a learning-at-home, do it yourself bike mechanic:

    I recently replaced the 68x127 bottom bracket on my Trek 930 mountain bike, successfully. Then I
    thought I'd replace a couple chain rings on the crank, but got a good deal on a crank set. Oops,
    didn't know what I got wouldn't work, I obviously assumed a bit too much universality... when I
    mount the new crank on the bottom bracket, the chainrings are way too far away from the frame, the
    front deraileur doesn't go out that far.

    Comparing the old crank to the new, the old crank's mounting hole doesn't 'reach' as far inside of
    the chainrings as the new one does, therefore the new one sets the rings out too far. (Make sense?)

    Do I get a shorter bottom bracket to use with this crank? What length would I get? How does one
    determine/measure/specify/pair this up with a crank?

    What do I look for when purchasing a new crank? How does one determine/measure/specify how far the
    mounting hold 'reaches' in? I'm wondering if I'll be able to find an inexpensive replacement for the
    Exage 500LX crank I have now.

    Thanks in advance for your tips and knowledge,

    David
     
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  2. Bill Kingson

    Bill Kingson Guest

    On 20 May 2003 12:23:16 -0700, [email protected] (Kelling) wrote:

    >Do I get a shorter bottom bracket to use with this crank? What length would I get? How does one
    >determine/measure/specify/pair this up with a crank?

    I asked similar questions when I upgraded to a triple crank on my 1980 road bike. It had an old cup
    'n' cone bottom bracket and I had no idea how to sort out what BB cartridge to use with my cranks. I
    asked here on rec.bicycles.tech and got the answer, "Use the size that's specified by the
    manufacturer".

    I went to the Shimano site and downloaded a spec sheet for my cranks.

    http://bike.shimano.com/services/tech_info_a.asp

    Sure enough, there was a BB specification right in the document. I'd never replaced cranks before,
    but it went together easily. After a few adjustments on the new derailers, everything worked great.

    My 2ยข

    Bill Kingson Caribou, Maine
     
  3. A Muzi

    A Muzi Guest

    "Kelling" <[email protected]> wrote in message
    news:[email protected]...
    > Hi!
    >
    > Please help a learning-at-home, do it yourself bike mechanic:
    >
    > I recently replaced the 68x127 bottom bracket on my Trek 930 mountain bike, successfully. Then I
    > thought I'd replace a couple chain rings on the crank, but got a good deal on a crank set. Oops,
    > didn't know what I got wouldn't work, I obviously assumed a bit too much universality... when I
    > mount the new crank on the bottom bracket, the chainrings are way too far away from the frame, the
    > front deraileur doesn't go out that far.
    >
    > Comparing the old crank to the new, the old crank's mounting hole doesn't 'reach' as far
    > inside of the chainrings as the new one does, therefore the new one sets the rings out too
    > far. (Make sense?)
    >
    > Do I get a shorter bottom bracket to use with this crank? What length would I get? How does one
    > determine/measure/specify/pair this up with a crank?
    >
    > What do I look for when purchasing a new crank? How does one determine/measure/specify how far the
    > mounting hold 'reaches' in? I'm wondering if I'll be able to find an inexpensive replacement for
    > the Exage 500LX crank I have now.
    >
    > Thanks in advance for your tips and knowledge,
    >
    > David

    Ask the person who sold you the crank what model it is and then get the correct spindle for that
    crank. What don't you like about your Exage LX crank? It is 110/74, making it much more useful than
    anything Shimano mankes today. Virtually every ring size from 24 to 58 teeth is readily available
    everywhere on earth!

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

    Kelling Guest

    "A Muzi" <[email protected]> wrote in message news:<[email protected]>...
    > "Kelling" <[email protected]> wrote in message
    > news:[email protected]...
    > > Hi!
    > >
    > > Please help a learning-at-home, do it yourself bike mechanic:
    > >
    > > I recently replaced the 68x127 bottom bracket on my Trek 930 mountain bike, successfully. Then I
    > > thought I'd replace a couple chain rings on the crank, but got a good deal on a crank set. Oops,
    > > didn't know what I got wouldn't work, I obviously assumed a bit too much universality... when I
    > > mount the new crank on the bottom bracket, the chainrings are way too far away from the frame,
    > > the front deraileur doesn't go out that far.
    > >
    > > Comparing the old crank to the new, the old crank's mounting hole doesn't 'reach' as far inside
    > > of the chainrings as the new one does, therefore the new one sets the rings out too far. (Make
    > > sense?)
    > >
    > > Do I get a shorter bottom bracket to use with this crank? What length would I get? How does one
    > > determine/measure/specify/pair this up with a crank?
    > >
    > > What do I look for when purchasing a new crank? How does one determine/measure/specify how far
    > > the mounting hold 'reaches' in? I'm wondering if I'll be able to find an inexpensive replacement
    > > for the Exage 500LX crank I have now.
    > >
    > > Thanks in advance for your tips and knowledge,
    > >
    > > David
    >
    > Ask the person who sold you the crank what model it is and then get the correct spindle for that
    > crank. What don't you like about your Exage LX crank? It is 110/74, making it much more useful
    > than anything Shimano mankes today. Virtually every ring size from 24 to 58 teeth is readily
    > available everywhere on earth!

    David says: The old one is quite worn, it has some "short teeth" on it and is starting to skip when
    I push hard. Thanks for the suggestions!
     
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