BMX BB cup length

Discussion in 'BMX & Dirt Jumping' started by ThePriceSeliger, Dec 25, 2007.

  1. ThePriceSeliger

    ThePriceSeliger Mushhead

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    Is it 68 mm or is it something else?
     

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  2. cmc

    cmc Turbo Monkey

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    not sure about the mm. . . . but the 4 kinds of bmx bottom brackets are American, Mid, Spanish, and Euro.
     
  3. ThePriceSeliger

    ThePriceSeliger Mushhead

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    Yep, that didn't help me at all. I'm getting profile BMX cranks for my Dobermann and didn't know if their Euro BB is the correct length since they don't specify which length.
     
  4. -dustin

    -dustin boring

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    first, I would opt for FSAs euro bb. I like their use of an adjustable cup.

    Second, like american bbs, it'll come with necessary spacers and such to fit your shell.
     
  5. ThePriceSeliger

    ThePriceSeliger Mushhead

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    Actually, let me get it this way. Will the spindle be long enough for a 68mm bb shell?
     
  6. -dustin

    -dustin boring

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    if coming from Quality or some other non BMX specific distributor, from my experience, yes.
     
  7. ThePriceSeliger

    ThePriceSeliger Mushhead

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    It's coming stright from Profile. So I'm guessing it will be ok. I'm going to call them tomorrow and work something out.
     
  8. BikeSATORI

    BikeSATORI Monkey

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    you're not looking for a "BB cup length"... that's irrelevant in bmx since the cups are free floating.

    Spindle length is what you seek... but seems you realize that now.

    Profiles should fit a 68 shell no worries (most common in bmx), as they usually come in 5 3/4" lengths (sometimes 6" in mtb apps.)... where some FSA's spindles (all FSA ti) come in only 5.5" and make for a squeeze on some bikes depending on the spacers you run between the bearing and the arm.
    I've also gritted out more FSA euro bearings than any other. The lockring is a nice and easy way to dial it in if your internal tube spacer isn't exactly correct, but that usually isn't too much of a problem if you set-up correctly with the fixed cups. I had the best luck with Wethepeople bearings when they used a double wide single bearing on each side, instead of just two regular bearings next to eachother in each cup... don't think those are still made though.
    hope that helps a bit.
     
  9. snaky69

    snaky69 Monkey

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    You're bound to need the 6'' spindle, as opposed to the 5 and 3/4'' spindle that comes on their bmx cranks.
     
  10. BikeSATORI

    BikeSATORI Monkey

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    hey snaky, what's up.
    I gotta disagree though. I was running the short FSA ti 5.5" spindle on my Molly before I went with the fly cranks (which are also short and only fit 68mm and under). The only time I needed the full 6" spindle was on mtbs with 73mm shells and larger, AND with a chainguide set up and 9spd chainline, like on my SplinterMX for example.
    Profile 5 3/4" will be plenty on the Dob.
     
  11. ThePriceSeliger

    ThePriceSeliger Mushhead

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    Exactly what I wanted to hear. Thank you.
     
  12. snaky69

    snaky69 Monkey

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    Yes, but you're running bmx spacing and a 24''wheel. I'm running 135mm spacing, it makes the chainstays flare out more and I need a 6'' spindle on my nempro(currently have a 5 and 3/4'' and I bent it due to the cranks not having enough insertion), this is also what profile recommends on their website for people with 68/73mm bottom brackets.

    Mind you, without a spider or anything of the like(bash guard, what have you) I figure 5 3/4 might be enough. I guess it's time for the OP to pull out a ruler and check it out.
     
  13. BikeSATORI

    BikeSATORI Monkey

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    Ran wethepeople royal cranks with the same 5.5" FSA ti spindle on my Eastern26 Proto, with 135mm disc rear spacing/hub... and plenty of clearance for a 2.4" tire too. No chainline probs.
    Honestly, the 6" is almost Too wide for my SplinterMX, if I weren't running the external Fly euro-spanish bearing converters, my crank arm bolts might bottom out on the spindle unless I replaced that 20mm of extra width with spacers. You must be running a good amount of spacers between your crank arms and bearings on your 68 shell.
     
  14. snaky69

    snaky69 Monkey

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    I'll send a picture your way when my Profile crankset arrives at the LBS, it's the holidays so I don't expect it to come before january, most suppliers are on a holiday too methinks.
     
  15. rpet

    rpet Turbo Monkey

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    how much insertion is necessary? I'm running demolition Medials LTs on 68mm/euro on my eastern. works fine so far (only 3 rides), but it would suck to bust the ti spindle.

    thx
    -r