Advertise on Bikeforums.net



User Tag List

Results 1 to 9 of 9
  1. #1
    fishologist cohophysh's Avatar
    Join Date
    May 2006
    Location
    Pacific Northwest
    My Bikes
    Diamondback MTB; Leader 736R
    Posts
    1,200
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    rear triangle and BB

    Hi,
    If I spread a rear triangle (according to SB) should I replace the BB with a longer spindle? In other words, if I open the rear triangle let's say 6mm, should I get a BB with a longer spindle equal to that length?
    We cannot solve problems with the same level of consciousness that created them. A.E.

    1990 Diamond Back MTB
    2007 Leader 736R
    www.cohocyclist.blogspot.com
    http://www.loopd.com/members/cohocyclist/Default.aspx



  2. #2
    A little North of Hell
    Join Date
    Mar 2006
    Posts
    4,354
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    in the middle

    No. Rear wheel will still be centered between dropouts with 3mm of spacers on each side.
    [SIGPIC][/SIGPIC]
    XXXI

  3. #3
    Elitist Troglodyte DMF's Avatar
    Join Date
    Jun 2006
    Location
    Dallas
    My Bikes
    03 Raleigh Professional (steel)
    Posts
    6,896
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Actually, that's an interesting question.

    The rear chainline is measure to the center cog of the sprocket cluster, which would be located 6mm/2 = 3mm farther from the center of the dropouts if the cluster is the same width as the old one. So it would seem that the front chainline should be moved out 3mm to match. Otherwise,

    chainline difference = (spread/2 - (cluster width difference)/2)

    I'd like to see that demonstrated by measurement, though, before I acted on it.
    Stupidity got us into this mess - why can't it get us out?

    - Will Rogers

  4. #4
    biked well well biked's Avatar
    Join Date
    Jul 2005
    Posts
    6,797
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    Yeah, assuming the reason you cold set the frame is to use a different, wider O.L.D. hub, you've probably changed your optimum chainline some. One of the main ideas behind bb spindle length is to get as close to optimum chainline as possible, so it seems likely you might need a slightly longer bb spindle for the best chainline.

  5. #5
    A little North of Hell
    Join Date
    Mar 2006
    Posts
    4,354
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    didn't think geared.

    Quote Originally Posted by Soil_Sampler View Post
    No. Rear wheel will still be centered between dropouts with 3mm of spacers on each side.
    Fixed Gear thinking.^^^^^^^


    well biked is right if you are going from 130mm to 135mm. or some other spacing variation(geared)
    [SIGPIC][/SIGPIC]
    XXXI

  6. #6
    fishologist cohophysh's Avatar
    Join Date
    May 2006
    Location
    Pacific Northwest
    My Bikes
    Diamondback MTB; Leader 736R
    Posts
    1,200
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    thanks
    We cannot solve problems with the same level of consciousness that created them. A.E.

    1990 Diamond Back MTB
    2007 Leader 736R
    www.cohocyclist.blogspot.com
    http://www.loopd.com/members/cohocyclist/Default.aspx



  7. #7
    Black La Lane GeoLes's Avatar
    Join Date
    Dec 2004
    Location
    Maplewood, NJ
    My Bikes
    EPX 303 (You probably never heard of it)
    Posts
    317
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    All the pale bike rider needs is a suntan.

  8. #8
    fishologist cohophysh's Avatar
    Join Date
    May 2006
    Location
    Pacific Northwest
    My Bikes
    Diamondback MTB; Leader 736R
    Posts
    1,200
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    :
    Quote Originally Posted by GeoLes View Post
    All the pale bike rider needs is a suntan.
    We cannot solve problems with the same level of consciousness that created them. A.E.

    1990 Diamond Back MTB
    2007 Leader 736R
    www.cohocyclist.blogspot.com
    http://www.loopd.com/members/cohocyclist/Default.aspx



  9. #9
    Mechanic/Tourist
    Join Date
    Apr 2007
    Location
    Syracuse, NY
    My Bikes
    2008 Novara Randonee - love it. Would have more bikes if I had time to ride them all. Previous bikes: 1968 Motobecane Mirage, 1972 Moto Grand Jubilee (my fav), Jackson Rake 16, 1983 C'dale ST500.
    Posts
    4,830
    Mentioned
    5 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by cohophysh View Post
    Hi,
    If I spread a rear triangle (according to SB) should I replace the BB with a longer spindle? In other words, if I open the rear triangle let's say 6mm, should I get a BB with a longer spindle equal to that length?
    It depends on the centerline of the rear cluster you are installing vs. the centerline of the chainwheel set. Need to properly spread the triangle so centered and then check chainline to see what is needed. See Sheldon for chainline info - redundant to go into it here.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •