Cartridge BB spindle length compatibilty

Discussion in 'Australia and New Zealand' started by lemmiwinks.au@gmail.com, Feb 21, 2008.

  1. I'm upgrading the cup and cone BB in my super light weight, incredibly
    sexy and fast (well compared to all my other bikes anyway) Shogun Tri-
    sport 14 speed road bike. The Shimano Exage 300EX cranks, rear
    dérailleur and hubs date it to the early 90's I think.

    Anyway, I measured the old BB spindle to be 119.87mm, so lets call it
    120mm. This was confirmed by info on the late, great Sheldon Brown's
    website after I pulled the spindle out and matched the 3N marked on
    the spindle to the table on his site: http://sheldonbrown.com/bbsize.html
    The LBS didn't know what I was talking about when I said the spindle
    was 120mm (I neglected to mention that it wasn't a cartridge BB so
    this may have caused them confusion) and offered me 118mm or 122mm
    replacements.

    In the end I took the spindle in to them, they measured it at 119mm
    and recommended a 118mm cartridge replacement which I bought. After
    mulling it over for a while, I'm now concerned that the inner ring may
    foul on the chainstay (though obviously I'm yet to try it) and there's
    the issue of chainline, but I'm going to be out by + or - 2mm either
    way depending on if I use a 118mm or a 122mm BB. Apart from
    rebuilding the cup and cone BB which I'd rather not do, what should I
    do? Is 2mm that big of a deal when it comes to chainline?
     
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  2. lemmiwinks.au@gmail.com wrote:

    > I'm upgrading the cup and cone BB in my super light weight,
    > incredibly sexy and fast (well compared to all my other bikes
    > anyway) Shogun Tri- sport 14 speed road bike. The Shimano
    > Exage 300EX cranks, rear dérailleur and hubs date it to the
    > early 90's I think.
    >
    > Anyway, I measured the old BB spindle to be 119.87mm, so lets
    > call it 120mm. This was confirmed by info on the late, great
    > Sheldon Brown's website after I pulled the spindle out and
    > matched the 3N marked on the spindle to the table on his site:
    > http://sheldonbrown.com/bbsize.html The LBS didn't know what I
    > was talking about when I said the spindle was 120mm (I
    > neglected to mention that it wasn't a cartridge BB so this may
    > have caused them confusion) and offered me 118mm or 122mm
    > replacements.
    >
    > In the end I took the spindle in to them, they measured it at
    > 119mm and recommended a 118mm cartridge replacement which I
    > bought. After mulling it over for a while, I'm now concerned
    > that the inner ring may foul on the chainstay (though
    > obviously I'm yet to try it) and there's the issue of
    > chainline, but I'm going to be out by + or - 2mm either
    > way depending on if I use a 118mm or a 122mm BB. Apart from
    > rebuilding the cup and cone BB which I'd rather not do, what
    > should I do? Is 2mm that big of a deal when it comes to
    > chainline?


    2mm difference overall would be 1mm each side, and that's as
    close as you can hope to get.

    But there's another issue. Modern sealed square-taper BBs are
    symmetrical. Sheldon says yours is asymmetrical. He goes on
    to suggest 124mm as the symmetrical equivalent (to get the
    chainwheel side correct). This will move the LH crank further
    out, but that won't be an issue.

    I haven't seen 124mm JIS square taper BBs available, so
    122/122.5 is likely to be what you want (only 1mm shorter on
    the RH side).

    John
     
  3. On Feb 22, 10:11 am, John Henderson <jhenRemoveT...@talk21.com> wrote:

    > 2mm difference overall would be 1mm each side, and that's as
    > close as you can hope to get.
    >
    > But there's another issue. Modern sealed square-taper BBs are
    > symmetrical. Sheldon says yours is asymmetrical. He goes on
    > to suggest 124mm as the symmetrical equivalent (to get the
    > chainwheel side correct). This will move the LH crank further
    > out, but that won't be an issue.
    >
    > I haven't seen 124mm JIS square taper BBs available, so
    > 122/122.5 is likely to be what you want (only 1mm shorter on
    > the RH side).
    >
    > John


    Hmm, thanks John I failed to read Sheldon's page thoroughly enough.
    The longest that the LBS has in stock is 122mm so I think I will take
    it back and swap it for that.
     
  4. BT Humble

    BT Humble Guest

    lemmiwinks wrote:
    > I'm upgrading the cup and cone BB in my super light weight, incredibly
    > sexy and fast (well compared to all my other bikes anyway) Shogun Tri-
    > sport 14 speed road bike. The Shimano Exage 300EX cranks, rear
    > dérailleur and hubs date it to the early 90's I think.


    Bah! What would you want to ride such a heavy, slow, low-spec old
    thing for? ;-)


    BTH
     
  5. On Feb 23, 10:09 pm, BT Humble <bt_hum...@bigpond.com> wrote:
    > lemmiwinks wrote:
    > > I'm upgrading the cup and cone BB in my super light weight, incredibly
    > > sexy and fast (well compared to all my other bikes anyway) Shogun Tri-
    > > sport 14 speed road bike. The Shimano Exage 300EX cranks, rear
    > > dérailleur and hubs date it to the early 90's I think.

    >
    > Bah! What would you want to ride such a heavy, slow, low-spec old
    > thing for? ;-)
    >
    > BTH


    :-D

    We're a perfect match that bike and I.
     
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