Advertise on Bikeforums.net



User Tag List

Results 1 to 11 of 11
  1. #1
    W.W.DZ.D? cedricbosch's Avatar
    Join Date
    Sep 2006
    Location
    Arizona
    Posts
    1,978
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    Shorter BB spindle to fix chainline?

    I converted a cheap-o department store bike into a beater single speed. The only problem is the chainline really sucks. I'm using a single-speed Shimano cog in the back, and a chainring on the middle-ring location of a triple crankset. The problem is that the chainring is too far from the frame. I'd like to bring it closer and I think a shorter BB spindle is the best idea. Short of taking the cranks off, how can I tell what length I have? If you had to guess, what length BB spindle would you choose to move the chainline ~5mm closer to the frame?

    Thanks!

    Cat 1 meter- 15%

  2. #2
    Zan
    Zan is offline
    Senior Member Zan's Avatar
    Join Date
    Oct 2007
    Location
    Waterloo, ONT
    My Bikes
    Road: Trek 1.5 (2007). Mountain: Santa Cruz Chameleon (2008). Beater: Peugeot Recorde du Monde (1850)
    Posts
    1,417
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    is it possible to use spacers to shift your rear cog out?
    -- Zan

    "Every dog needs a squeak toy."

  3. #3
    W.W.DZ.D? cedricbosch's Avatar
    Join Date
    Sep 2006
    Location
    Arizona
    Posts
    1,978
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    I dont think so- it's a single speed freewheel.
    Cat 1 meter- 15%

  4. #4
    AEO
    AEO is offline
    Senior Member AEO's Avatar
    Join Date
    Jun 2007
    Location
    A Coffin Called Earth. or Toronto, ON
    My Bikes
    Bianchi, Miyata, Dahon, Rossin
    Posts
    12,245
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    I don't get it, can't you just pull off the cranks and measure the BB with some calipers?
    Food for thought: if you aren't dead by 2050, you and your entire family will be within a few years from starvation. Now that is a cruel gift to leave for your offspring. ;)
    http://sanfrancisco.ibtimes.com/arti...ger-photos.htm

  5. #5
    I have senior moments... bikinfool's Avatar
    Join Date
    Oct 2008
    Location
    Woodside, CA
    My Bikes
    Many
    Posts
    2,153
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Just get a bb with a spindle 10mm shorter than the one you have now
    suum quique
    Mountain bikes: Santa Cruz Hecklers (99, 02, 07), Santa Cruz Nomad, Moots YBB, Trek OCLV Pro Issue, American Breezer
    Road bikes: TST, Trek 2300 (Carbon/Alum)

  6. #6
    cab horn
    Join Date
    Jun 2004
    Location
    Toronto
    My Bikes
    1987 Bianchi Campione
    Posts
    28,292
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by AEO View Post
    I don't get it, can't you just pull off the cranks and measure the BB with some calipers?
    This is exactly what the OP needs to do.
    Mes compaingnons cui j'amoie et cui j'aim,... Me di, chanson.

  7. #7
    cab horn
    Join Date
    Jun 2004
    Location
    Toronto
    My Bikes
    1987 Bianchi Campione
    Posts
    28,292
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by bikinfool View Post
    Just get a bb with a spindle 10mm shorter than the one you have now
    Assuming it's symmetrical. For example 110 shimano cart to 107 bb results in the exact same chainline.
    Mes compaingnons cui j'amoie et cui j'aim,... Me di, chanson.

  8. #8
    I have senior moments... bikinfool's Avatar
    Join Date
    Oct 2008
    Location
    Woodside, CA
    My Bikes
    Many
    Posts
    2,153
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by operator View Post
    Assuming it's symmetrical. For example 110 shimano cart to 107 bb results in the exact same chainline.
    Gotta guess that's it's not symmetrical too? Not fair...
    suum quique
    Mountain bikes: Santa Cruz Hecklers (99, 02, 07), Santa Cruz Nomad, Moots YBB, Trek OCLV Pro Issue, American Breezer
    Road bikes: TST, Trek 2300 (Carbon/Alum)

  9. #9
    Call me The Breeze I_bRAD's Avatar
    Join Date
    Aug 2006
    Location
    Corbyville Ontario
    My Bikes
    2004 Litespeed Siena, 1996 Litespeed Obed, 1992 Miele (unknown model), 1982 Meile Uno LS.
    Posts
    3,699
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Do you know what your current chainline is?

  10. #10
    Senior Member
    Join Date
    Sep 2008
    Location
    Loveland, CO
    My Bikes
    Two LOOK 585s, one KG461
    Posts
    4,987
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    The normal chain line is 47-48mm from the center of the ST to the tip of a tooth on the big ring. Measure from the side of the ST and add half the ST diameter.

  11. #11
    Your mom
    Join Date
    Aug 2006
    Posts
    2,546
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    The short answer is that there's no simple way that I've found to estimate chainline based on BB spindle length. The long answer is that, if you get a shorter BB spindle, you can probably make it work just fine, within a couple mm. Is there any option for respacing and -dishing your rear wheel to fix?

Posting Permissions

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