Advertise on Bikeforums.net



User Tag List

Results 1 to 17 of 17
  1. #1
    Evil Capitalist >8D Speed2XS's Avatar
    Join Date
    Oct 2008
    Location
    Bakersfield, CA, USA
    My Bikes
    Not too many, but I plan for more. **UPDATE** too many!
    Posts
    143
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    A cup & cone spindle length question

    Hello,

    I am having problems discerning the correct length of a cup/cone spindle I am trying to replace. I have measured this spindle with two different instruments; one shows it to be a 124mm spindle, while the other shows it to be a 122mm spindle. The spindle is stamped 3S, and by Sheldon Browns website this spindle should be a 121.5mm. I would trust this number except the A and C lengths differ from that which Mr Browns website indicates this spindle to be. I need this number to achieve a good chainline for a fixed gear bicycle I am building for my wife.

    Am I making this too difficult and should I just take the spindle specs per Mr. Brown as gospel?

    Thanks everyone in advance.


    Laurence


  2. #2
    Senior Member
    Join Date
    May 2009
    Posts
    2,050
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Make sure you're measuring it in the same place, and zero your instruments or check their zero if you can't.

    Anyway, I find it pointless to measure the exact length of spindles because the forming process mashes up a rim of extra metal on the ends. When they grind the square taper flats they force up little ridges on the ends which mess up the measurement. I would therefore definitely go with the book value because there's "slop" in the real world value, or in other words, the crank arms would sit in the same place even if you ground off the ridges and honed the spindle to 121.500mm.

    Also, don't forget that you can always shim the chainring or the cog (they make cog shims don't they? I believe they do.)
    Last edited by garage sale GT; 05-16-09 at 07:13 PM.

  3. #3
    Senior Member
    Join Date
    Oct 2008
    Location
    Ohio
    My Bikes
    Franklin Frames Custom, Rivendell Bombadil, '83 Specialized Stumpjumper
    Posts
    1,289
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by Speed2XS View Post
    Hello,

    I am having problems discerning the correct length of a cup/cone spindle I am trying to replace. I have measured this spindle with two different instruments; one shows it to be a 124mm spindle, while the other shows it to be a 122mm spindle. The spindle is stamped 3S, and by Sheldon Browns website this spindle should be a 121.5mm. I would trust this number except the A and C lengths differ from that which Mr Browns website indicates this spindle to be. I need this number to achieve a good chainline for a fixed gear bicycle I am building for my wife.

    Am I making this too difficult and should I just take the spindle specs per Mr. Brown as gospel?

    Thanks everyone in advance.


    Laurence



    What's the brand of BB and crank?

    What are the two instruments?

    A 121.5 is a 122, depending on the accuracy of any measuring tool and their interpretation. Don't worry about it. A 3s is listed as 121.5mm from my paper literature.

    Mr. Browns axle specs are simply re-posted specs that have been in print long before the web became what it is now. Gospel? ..... no.

  4. #4
    Senior Member johnknappcc's Avatar
    Join Date
    Feb 2009
    Location
    Columbus, OH
    My Bikes
    A beautiful columbus steel frame, 1986 Schwinn Voyageur touring bike, Currently Undergoing Overhaul
    Posts
    910
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    I might be completely off here, but mine BB spindle is the same, 121.5mm. Mine is also designed for a triple crank, so your chainline might be off on a fixie. That is pretty wide for a single chainring and crank. You may need a smaller spindle to get the proper chainline, but again, I could be totally wrong. Maybe someone else has tried it?

  5. #5
    Evil Capitalist >8D Speed2XS's Avatar
    Join Date
    Oct 2008
    Location
    Bakersfield, CA, USA
    My Bikes
    Not too many, but I plan for more. **UPDATE** too many!
    Posts
    143
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Thanks everyone for the responses.

    My crank was originally a double I think, the bike is like a 71-73 random Japanese bike. My thought was similar to some of the responses posted... varying tolerances in manufacturing, as long as the race for the bearing is properly placed, and the taper for the cranks was right, the crank would work as it should.

    My goal is to find the right size BB to place my chainring at a 42mm offset. The numbers show that I need to whack off 4mm. So I need four mm off what ever size I have now.

    I guess I'll buy one using the 3S specs and take a chance.

  6. #6
    Senior Member
    Join Date
    Oct 2008
    Location
    Ohio
    My Bikes
    Franklin Frames Custom, Rivendell Bombadil, '83 Specialized Stumpjumper
    Posts
    1,289
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Hold on ...... you don't hack off mm's on an axle! This will make no difference in your chainline, it will only shorten the taper, which is the most important part of the axle as it holds the arm on. DO NOT do this !

    You could make your life a little simple and just use a cartridge bearing BB, you can adjust the chainline with it by either using spacers, or removing the lip on the drive side cup .
    Last edited by Garthr; 05-17-09 at 11:15 AM.

  7. #7
    cab horn
    Join Date
    Jun 2004
    Location
    Toronto
    My Bikes
    1987 Bianchi Campione
    Posts
    28,295
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    The only thing you need to be concerned about is if it's assymetrical. If it's not, and you only need 4mm less, then by obviousness the spindle length you need is 8mm shorter than what you have (split the difference on both sides). I'm going to assume you already measured the chainline of your current crank, with the current bb spindle in both the outer, and inner positions before you began this exercise. And that's with the crank at the proper torque spec.

    Otherwise, you're 4mm answer is as good as a random number generator.
    Mes compaingnons cui j'amoie et cui j'aim,... Me di, chanson.

  8. #8
    Senior Member
    Join Date
    May 2009
    Posts
    2,050
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    I think you need a 107 to use the inner ring with a typical road crank or a 103 to use the outer, provided you have the standard 42mm chainline on the rear wheel and a 68mm bb.

    MEASURE! Why don't you button the old bb back up and measure your chainline? Then you'll know for sure how much shorter it should be to get 40.5-42mm which is what standard track hubs are. (measure from the center of the downtube or make a mark 34mm from one end of your bb shell.)

  9. #9
    Evil Capitalist >8D Speed2XS's Avatar
    Join Date
    Oct 2008
    Location
    Bakersfield, CA, USA
    My Bikes
    Not too many, but I plan for more. **UPDATE** too many!
    Posts
    143
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Hi everyone!

    I think my statement misled some folks.

    I don't intend to actually "hack off" length from my spindle. I was simply trying to determine the actual length of my current spindle so I could replace it with a new sealed bearing BB to create the correct offset for my chainline. I have measured the chainline difference and feel comfortable in my measurements. The only thing up in the air was the spindle length of my current BB. Although the current spindle is asymmetrical, The shorter length was on the drive (chainring) side, and flipping it would not create the desired chainline. I just wasn't sure about my measurement of the overall length, which I suppose is what you get when using a $5 caliper from Home Depot

    Thanks all for the helpful input and I will update this thread to share my success, or failure, when it occurs.

  10. #10
    Evil Capitalist >8D Speed2XS's Avatar
    Join Date
    Oct 2008
    Location
    Bakersfield, CA, USA
    My Bikes
    Not too many, but I plan for more. **UPDATE** too many!
    Posts
    143
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by garage sale GT View Post
    I think you need a 107
    This was the number I arrived at with the 3S designated specs, as indicated by the red circles:


  11. #11
    Senior Member
    Join Date
    May 2009
    Posts
    2,050
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    I bet the spindle is matched to the crankset, though. If you get a symmetrical bb, one of your pedals will be off by a few mm.

    What I was trying to suggest is to measure your current chainline in front, then change the book value of the length by that amount, adjusted for the offset. First of all, you can't put your caliper on the bb you order until you get it, & second of all, it still won't tell you if the distance and angle of the flats is correct relative to the bearing cartridge or cup threads.

    Have you measured your inner ring? It sounds like you are going by the outer ring. You may find you're pretty close to 42 now.

  12. #12
    Evil Capitalist >8D Speed2XS's Avatar
    Join Date
    Oct 2008
    Location
    Bakersfield, CA, USA
    My Bikes
    Not too many, but I plan for more. **UPDATE** too many!
    Posts
    143
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by garage sale GT View Post
    I bet the spindle is matched to the crankset, though. If you get a symmetrical bb, one of your pedals will be off by a few mm.

    What I was trying to suggest is to measure your current chainline in front, then change the book value of the length by that amount, adjusted for the offset. First of all, you can't put your caliper on the bb you order until you get it, & second of all, it still won't tell you if the distance and angle of the flats is correct relative to the bearing cartridge or cup threads.

    Have you measured your inner ring? It sounds like you are going by the outer ring. You may find you're pretty close to 42 now.
    My crankset is of the swedged variety, so using anything but the outer chainring isn't an option.

    As indicated by the image I included before, my chainline measures 46mm in the front, and 42 (not represented) in the rear, on a redished 27" wheel running suicide with a BB lock ring secured by loctite. I do run a front brake.

    Unfortuantely the frame is at the powder coaters so reinstalling the BB is not an option, but before I disassembled it I measured everything. Soooo... if in fact my crank fits differently on MY spindle than it will on other JIS tapered spindles then I can measure all I want and never achieve perfect chainline unless by chance, as like you said I cant measure the new one until I receive it, which by then would be pointless. If I can get it within 1mm, instead of the 4mm I had been running it at with the factory spindle, I will be content.

  13. #13
    Your mom
    Join Date
    Aug 2006
    Posts
    2,546
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    I wouldn't use a swaged crankset for a fixie. That's asking for trouble, IMHO. Not only with your chain tension be dicey, but if it fails, it won't be pretty.

    I've been in your shoes before, and I can honestly say that it is quicker, easier, and most probably cheaper to buy a new crankset and bottom bracket than spend hours trying to fine-tune the chainline with random parts you have around. And I am the world's cheapest b@stard.

    On my rain bike, I have a cheapo Origin 8 crankset I got for around $30. And it tells me right on the box what size bottom bracket I need. Add $20 for a bottom bracket and you'll never have to worry about it again.

  14. #14
    Evil Capitalist >8D Speed2XS's Avatar
    Join Date
    Oct 2008
    Location
    Bakersfield, CA, USA
    My Bikes
    Not too many, but I plan for more. **UPDATE** too many!
    Posts
    143
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by tellyho View Post
    On my rain bike, I have a cheapo Origin 8 crankset I got for around $30.
    Where did you find it for only $30? Im out of work right now, so the wife is the only one bringing home a check, my cheapness (and yes I'm cheap ) isnt the deciding factor in this right now. We just have limited funds, which is why we're redoing my old bike for her instead if buying her a new one of her own.

  15. #15
    Your mom
    Join Date
    Aug 2006
    Posts
    2,546
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    In that case, I'd seriously consider making it a single speed, just for safety's sake. I've thrown the chain on my fixie, and it's scary as hell. Don't know how or why, I had just checked the drivetrain out.

    As far as the crankset, there's a shop around here that pretty much sells at wholesale, so I guess it's a one-off.

  16. #16
    Evil Capitalist >8D Speed2XS's Avatar
    Join Date
    Oct 2008
    Location
    Bakersfield, CA, USA
    My Bikes
    Not too many, but I plan for more. **UPDATE** too many!
    Posts
    143
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Ive been running this very bike fixed for 8 months, with no problems, with the 4mm out chainline. Now that it is going to my wife I am trying to get the things done to it I never did for myself, like straighten the chainline.

    That being said I found a guy to sell me the origin 8 crankset for $40.00. My wife had better never complain that I never do anything for her.

  17. #17
    meb
    meb is offline
    Senior Member meb's Avatar
    Join Date
    Aug 2003
    Location
    arlington, VA
    Posts
    1,745
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by Garthr View Post
    What's the brand of BB and crank?

    What are the two instruments?

    A 121.5 is a 122, depending on the accuracy of any measuring tool and their interpretation. Don't worry about it. A 3s is listed as 121.5mm from my paper literature.

    Mr. Browns axle specs are simply re-posted specs that have been in print long before the web became what it is now. Gospel? ..... no.
    3S is an assymetric 121.5. The long side is the equivalent of a symetric 127. This lets you mount a triple with a lesser Q-factor than a symetric spindle. I have a 3S myself-that is a Japanese convention.

Posting Permissions

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