Switching Parts Between Bikes - Bottom Bracket in Question

Discussion in 'Cycling Equipment' started by Rosco, Mar 16, 2004.

  1. Rosco

    Rosco Guest

    I'm looking to move some ~15 year old 7 speed Dura-Ace parts
    over to a different bike. The "donor bike" seems to have an
    Italian threaded bottom bracket (Shimano BB-7400 36x24T)
    whereas the "recipient bike" is English threaded. The
    Shimano square taper double crankset is still in very good
    shape, so I'd like to save it.

    Can someone confirm that the BB-7400 36x24T is indeed
    Italian? Secondly, what English threaded bottom bracket
    would folks suggest? I'm looking for something of only
    decent quality. After about a year, the parts will return to
    their original bike (assuming I can then afford a new
    Campagnolo parts set).
     
    Tags:


  2. Frank121

    Frank121 Guest

    36x24 is Italian...think of the stereotypical figures
    of the Italian movie starlets of the past as in 36-24-
    36 to remember.

    "rosco" <reverse-the-following"ocsor_g"@hotmail.com> wrote
    in message news:D[email protected]
    hlink.net...
    > I'm looking to move some ~15 year old 7 speed Dura-Ace
    > parts over to a different bike. The "donor bike" seems to
    > have an Italian threaded bottom bracket (Shimano BB-7400
    > 36x24T) whereas the "recipient bike" is English threaded.
    > The Shimano square taper double crankset is still in very
    > good shape, so I'd like to save it.
    >
    > Can someone confirm that the BB-7400 36x24T is indeed
    > Italian? Secondly, what English threaded bottom bracket
    > would folks suggest? I'm looking for something of only
    > decent quality. After about a year, the parts will
    return
    > to their original bike (assuming I can then afford a new
    > Campagnolo parts set).
     
  3. rosco wrote:
    > I'm looking to move some ~15 year old 7 speed Dura-Ace
    > parts over to a different bike. The "donor bike" seems to
    > have an Italian threaded bottom bracket (Shimano BB-7400
    > 36x24T) whereas the "recipient bike" is English threaded.
    > The Shimano square taper double crankset is still in very
    > good shape, so I'd like to save it.
    >
    > Can someone confirm that the BB-7400 36x24T is indeed
    > Italian?

    BB-7400 is Dura-Ace 1990-95.

    36x24t is Italian.

    See: http://sheldonbrown.com/bbsize.html#dura

    > what English threaded bottom bracket would folks suggest?
    > I'm looking for something of only decent quality. After
    > about a year, the parts will return to their original bike
    > (assuming I can then afford a new Campagnolo parts

    I'd recommend a UN53 or UN73 68 x 115.

    See: http://harriscyclery.net/site/page.cfm?PageID=49&Cat-
    egory=1050

    According to my Bottom Bracket Size database
    (http://sheldonbrown.com/bbsize.html#dura) this crank
    originally used a 112 asymmetrical spindle for use with a
    68 mm BB, but with modern symmetrical bbs you want to go a
    bit longer.

    Sheldon "We've Got 'Em" Brown +----------------------------------------------------
    +
    | A little inaccuracy sometimes saves tons of |
    | explanation. --H.H.Munro ("Saki")(1870-1916) |
    +----------------------------------------------------+
    Harris Cyclery, West Newton, Massachusetts Phone 617-244-
    9772 FAX 617-244-1041 http://harriscyclery.com Hard-to-find
    parts shipped Worldwide http://captainbike.com
    http://sheldonbrown.com
     
  4. Rosco

    Rosco Guest

    "Sheldon Brown" <[email protected]> wrote in message
    news:[email protected]...

    >
    > > what English threaded bottom bracket would folks
    > > suggest? I'm looking
    for
    > > something of only decent quality. After about a year,
    > > the parts will
    return
    > > to their original bike (assuming I can then afford a new
    > > Campagnolo
    parts
    >
    > I'd recommend a UN53 or UN73 68 x 115.
    >
    > See: http://harriscyclery.net/site/page.cfm?PageID=49&Cat-
    > egory=1050
    >
    > According to my Bottom Bracket Size database
    > (http://sheldonbrown.com/bbsize.html#dura) this crank
    > originally used a 112 asymmetrical spindle for use with a
    > 68 mm BB, but with modern symmetrical bbs you want to go a
    > bit longer.
    >

    One detail I forgot to mention...

    The donor rear wheel is 126mm spaced (w/ freewheel not
    cassette) whereas the recipient rear spacing is 130mm. I
    figured by changing the axle and adding some 2mm spacers to
    both sides I can make this work. Does this sound like a good
    approach given the relatively short time it will remain on
    the recipient bike?

    Will this approach dictate a slightly shorter bottom bracket
    spindle for the sake of chain line?
     
  5. A Muzi

    A Muzi Guest

    rosco wrote:

    > I'm looking to move some ~15 year old 7 speed Dura-Ace
    > parts over to a different bike. The "donor bike" seems to
    > have an Italian threaded bottom bracket (Shimano BB-7400
    > 36x24T) whereas the "recipient bike" is English threaded.
    > The Shimano square taper double crankset is still in very
    > good shape, so I'd like to save it.
    >
    > Can someone confirm that the BB-7400 36x24T is indeed
    > Italian? Secondly, what English threaded bottom bracket
    > would folks suggest? I'm looking for something of only
    > decent quality. After about a year, the parts will return
    > to their original bike (assuming I can then afford a new
    > Campagnolo parts set).
    >
    >
    Yes 36mm is Italian.

    That crank uses the same effective spindle dimensions as
    the classic Campagnolo Record 1046 and Nuovo Record 1046a.
    A score of other manufacturers produced similar dimension
    units but AFAIK only Phil Wood is currently in production.
    Still, since that was such a popular size for such a long
    time, compatible BBs abound across a wide range of price
    and quality.

    --
    Andrew Muzi www.yellowjersey.org Open every day since 1
    April, 1971
     
  6. rosco-<< Can someone confirm that the BB-7400 36x24T is
    indeed Italian?
    >><BR><BR>
    << Secondly, what English threaded bottom bracket would
    folks suggest? >><BR><BR>

    A 7400 in english threading?

    Or a UN-72 in 113mm length and english threading.

    Peter Chisholm Vecchio's Bicicletteria 1833 Pearl St.
    Boulder, CO, 80302
    (303)440-3535 http://www.vecchios.com "Ruote convenzionali
    costruite eccezionalmente bene"
     
  7. rosco asked:

    >>> what English threaded bottom bracket would folks
    >>> suggest? I'm looking for something of only decent
    >>> quality. After about a year, the parts will return to
    >>> their original bike (assuming I can then afford a new
    >>> Campagnolo parts

    I replied:

    >>I'd recommend a UN53 or UN73 68 x 115.
    >>
    >>See: http://harriscyclery.net/site/page.cfm?PageID=49&Cat-
    >>egory=1050
    >>
    >>According to my Bottom Bracket Size database
    >>(http://sheldonbrown.com/bbsize.html#dura) this crank
    >>originally used a 112 asymmetrical spindle for use with a
    >>68 mm BB, but with modern symmetrical bbs you want to go a
    >>bit longer.

    On redirect, rosco asked:

    > One detail I forgot to mention...
    >
    > The donor rear wheel is 126mm spaced (w/ freewheel not
    > cassette) whereas the recipient rear spacing is 130mm. I
    > figured by changing the axle and adding some 2mm spacers
    > to both sides I can make this work. Does this sound like a
    > good approach given the relatively short time it will
    > remain on the recipient bike?
    >
    > Will this approach dictate a slightly shorter bottom
    > bracket spindle for the sake of chain line?

    Derailer chainline is not a high-precision matter, unless
    you have indexed front shifting. A 113 would probably work
    too, but you might run into chanstay clearance issues or
    front derailer travel issues.

    If it were mine, I'd try a 113 with the awareness that it
    might be too short. However, if I had to actually _buy_ a BB
    without a trial fit, I'd go with the 115, which I'm sure
    will work.

    For road gearing, I prefer to bias the front chainline
    inward to favor the big ring, as long as that doesn't cause
    clearance or shifting issues. This approach allows efficient
    use of more rear sprockets with the big ring, at the cost of
    creating problems if you run the small chainring with the
    smaller rear sprockets. Since I generally avoid those
    combinations, this is a good tradeoff for me.

    Sheldon "Not An Exact Science" Brown +------------------------------------------------------
    ---------+
    | The poet Henry O'Meara (1848-1904) was my great-
    | grandfather | I've put his book "Ballads of America and
    | Other Poems" | on the Web at:
    | http://sheldonbrown.com/omeara |
    +-----------------------------------------------------------
    ----+ Harris Cyclery, West Newton, Massachusetts Phone 617-244-
    9772 FAX 617-244-1041 http://harriscyclery.com Hard-to-find
    parts shipped Worldwide http://captainbike.com
    http://sheldonbrown.com
     
  8. A Muzi

    A Muzi Guest

    > rosco-<< Can someone confirm that the BB-7400 36x24T is
    > indeed Italian? << Secondly, what English threaded bottom
    > bracket would folks suggest? >><BR><BR>

    Qui si parla Campagnolo wrote:
    > A 7400 in english threading? Or a UN-72 in 113mm length
    > and english threading.

    Maybe, but only because a standard taper crank ( The BB-7400
    is 100% interchangeable with Nuovo Record 1046a) will only
    go halfway up the taper of a UN-72.

    An ACH 115 is a much closer fit. & left arm sits out a bit.

    The BB-7400 spindle is asymmetric, so a simple "overall
    length" analysis is wanting for accuracy.
    --
    Andrew Muzi www.yellowjersey.org Open every day since 1
    April, 1971
     
  9. Rosco

    Rosco Guest

    "A Muzi" <[email protected]> wrote in message
    news:[email protected]...
    > > rosco-<< Can someone confirm that the BB-7400 36x24T is
    > > indeed Italian? << Secondly, what English threaded
    > > bottom bracket would folks suggest? >><BR><BR>
    >
    > Qui si parla Campagnolo wrote:
    > > A 7400 in english threading? Or a UN-72 in 113mm length
    > > and english threading.
    >
    > Maybe, but only because a standard taper crank ( The BB-
    > 7400 is 100% interchangeable with Nuovo Record 1046a) will
    > only go halfway up the taper of a UN-72.
    >
    > An ACH 115 is a much closer fit. & left arm sits out a
    > bit.
    >
    > The BB-7400 spindle is asymmetric, so a simple "overall
    > length" analysis is wanting for accuracy.
    > --
    > Andrew Muzi www.yellowjersey.org Open every day since 1
    > April, 1971
    >

    I got a UN52 in 113mm length at a LBS. At the shop, the FC-
    7400 crank arm seemed to fit similar to the BB-7400 it came
    off of (it slid on with hand pressure about 7/8 of the way
    down the taper of the crank arm). Installed the UN52 on the
    bike, and installed the drive side crank arm (torqued to
    about 20-25 ft pd). The crank arm was very much fully on
    the taper at this point. The resulting chainline seemed
    pretty close to spot-on (43.5mm). The LBS consulted
    Sutherlands Repair Manual, and concluded that the FC-7400
    was JIS and Campagnolo was the next best fit. However,
    Sutherlands gave no useful information on how to translate
    from the BB-7400 to a UN series cartridge sealed bearing
    based bottom bracket.
     
  10. A Muzi

    A Muzi Guest

    > "A Muzi" <[email protected]> wrote in message
    > news:[email protected]...
    -blah blah blah>-

    rosco wrote:
    > I got a UN52 in 113mm length at a LBS. At the shop, the
    > FC-7400 crank arm seemed to fit similar to the BB-7400 it
    > came off of (it slid on with hand pressure about 7/8 of
    > the way down the taper of the crank arm). Installed the
    > UN52 on the bike, and installed the drive side crank arm
    > (torqued to about 20-25 ft pd). The crank arm was very
    > much fully on the taper at this point. The resulting
    > chainline seemed pretty close to spot-on (43.5mm). The LBS
    > consulted Sutherlands Repair Manual, and concluded that
    > the FC-7400 was JIS and Campagnolo was the next best fit.
    > However, Sutherlands gave no useful information on how to
    > translate from the BB-7400 to a UN series cartridge sealed
    > bearing based bottom bracket.

    I actually dug up an NOS 7400 crank and looked at the actual
    spindle penetration.
    http://www.yellowjersey.org/photosfromthepast/7400_2.JPG

    (method: both were simply pressed firmly by hand, not
    properly torqued, the arm is brand new.)

    The difference from Campagnolo to Shimano spindle taper is
    much less than I remembered. Probably either would be OK
    given the right length and they're about the same price. I
    stand corrected.

    --
    Andrew Muzi www.yellowjersey.org Open every day since 1
    April, 1971
     
  11. Rosco

    Rosco Guest

    "rosco" <reverse-the-following"ocsor_g"@hotmail.com> wrote in message
    news:D[email protected]...
    > I'm looking to move some ~15 year old 7 speed Dura-Ace
    > parts over to a different bike. The "donor bike" seems to
    > have an Italian threaded bottom bracket (Shimano BB-7400
    > 36x24T) whereas the "recipient bike" is English threaded.
    > The Shimano square taper double crankset is still in very
    > good shape, so I'd like to save it.
    >
    > Can someone confirm that the BB-7400 36x24T is indeed
    > Italian? Secondly, what English threaded bottom bracket
    > would folks suggest? I'm looking for something of only
    > decent quality. After about a year, the parts will
    return
    > to their original bike (assuming I can then afford a new
    > Campagnolo parts set).
    >
    >

    Thanks to Andrew, Sheldon and Peter for your wonderful
    assistance!
     
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