Square Taper Bottom Bracket Query !

Discussion in 'Cycling Equipment' started by atlantis, Nov 10, 2011.

  1. atlantis

    atlantis New Member

    Joined:
    Sep 19, 2010
    Messages:
    59
    Likes Received:
    0
    Hi !
    My bike Btwin fitness 1.
    There was some play in my bottom bracket and I opened regreased and tightened it.
    The brand is a Vp .
    Thought I should install a shimano instead.
    Following is the specification with images:[​IMG][​IMG]

    After checking the measurements with a scale and reading the sticker , i realised that the available shimano bb are of 68x 118, 68x122 and 68x 122.5.

    Since i need a 68 x 120 , which size would be appropriate, I am unable to source the same size.
    What does the BC 1.37x24T stand for ?

    Should there be any other specifications that I need for a bottom bracket sizing.

    rgds
     
    Tags:


  2. alienator

    alienator Well-Known Member

    Joined:
    Jun 10, 2004
    Messages:
    12,596
    Likes Received:
    160
    Simple: contact Phil Wood: http://www.philwood.com/ .
     
  3. atlantis

    atlantis New Member

    Joined:
    Sep 19, 2010
    Messages:
    59
    Likes Received:
    0
    I am in india, i would be ordering online. If I take a size larger or smaller how much of a difference will it make ?
     
  4. 531Aussie

    531Aussie Well-Known Member

    Joined:
    Apr 11, 2004
    Messages:
    12,606
    Likes Received:
    137
    Hmm, what type of cranks do you have? Is it a triple chainring?
    I reckon 120mm sounds a teeny bit wide for a double, but maybe not. Do you remember how close the inside chainring was to the frame? I vaguely remember using 113mm axles in the 'old days', but I'm not sure. You might be able to get a better chain line with a narrower axle, but, to play it safe, maybe stick with the same (or similar) size.

    There's obviously bugger-all difference between 120mm and 118 or 122. There's a slight chance that the small chainring could hit the frame if you use a narrower axle (also because square-tapered cranks tend to go on a tiny bit more each time they're put on, coz the soft alu 'gives' a bit on the hard steel axle if they're done up tight), but I dunno how close it was with your 120mm axle. So, maybe play it safe and get the 122mm.

    The '1.37' is the diameter of the bottom bracket shell (1.37 inches), and the '24' is threads per inch (tpi). This is 'English threaded'. You definetly have to get a bottom bracket with these dimensions, as the other (less) commonly used size is 36mm diameter, which wont fit
     
  5. atlantis

    atlantis New Member

    Joined:
    Sep 19, 2010
    Messages:
    59
    Likes Received:
    0
    Its a triple chain ring 48 38 28, I'll get home and let you know the gap between the smallest chainring and the frame. Is the Shimano bottom bracket the UN series ( square taper ) all 1.37 shell size. Since the info online is only the width of the shell and the full size of the bottom bracket.
     
  6. 531Aussie

    531Aussie Well-Known Member

    Joined:
    Apr 11, 2004
    Messages:
    12,606
    Likes Received:
    137
    From what site are you gunna order it? They usually provide the dimensions. However, English thread (1.37" x 24tpi and 68mm across) is, by far, the most common size, so the buyer usually has to specify 'Italian thread' for the other size. I reckon just get the 122mm
     
  7. atlantis

    atlantis New Member

    Joined:
    Sep 19, 2010
    Messages:
    59
    Likes Received:
    0
    http://www.chainreactioncycles.com/Categories.aspx?CategoryID=144&SortBy=Price&BrandID=94

    http://www.jensonusa.com/store/sub/110-Bottom+Brackets-Square+Taper.aspx?s=1309&mfg=0&closeoutHotdeal=&use=&sort=Default&show=25&pricemin=0&pricemax=300

    I was looking at these websites.

    And the gap between the smallest chain ring and the chainstay is about 6mm
     
  8. 531Aussie

    531Aussie Well-Known Member

    Joined:
    Apr 11, 2004
    Messages:
    12,606
    Likes Received:
    137
  9. alfeng

    alfeng Well-Known Member

    Joined:
    Jul 23, 2005
    Messages:
    6,723
    Likes Received:
    126
    FWIW. The spectrum of Shimano's Square Taper BBs varies greatly so unless you were to replace your current BB with a number higher than UN-52? then there would be little benefit.

    Because the current BB's width is 68mm (instead of 73mm), I presume your bike has a steel frame so 'I' would opt for a 118mm spindle length ... if your bike had an aluminum frame, then I would choose the slightly longer spindle.

    Unless you are really unhappy with your current BB then I would not replace it ... OR, I would simply try to find a source in India which can measure-and-order replacements for the existing bearings ...

    • SOME cartridge bearings have their size molded onto the plastic discs which shroud the bearings.
     
Loading...
Loading...