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  1. #1
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    Square taper options for press-fit bottom brackets ?

    I'm considering a new full suspension bike. I rode a Giant Anthem today, which seems like a great bike but the press fit bottom bracket is not something I'm familiar with.

    I want to run a square taper bottom bracket with a long spindle. I am going to use a Mtn Tamer Triple, or a White Industries Limbo Spider, or my own homemade adapter to run an 18t granny ring. The gearing will be 18/28/38.

    Does anyone know if a company like Problem Solvers or Wheels Manufacturing has made an adapter kit that will allow a rider to use square taper bottom brackets on a press-fit bb like the one found on the Giant Anthem ?

  2. #2
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    Reputation: Procter's Avatar
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    So, couple thoughts:

    You're posting in the AM forum, but you cited a bike that is more of an XC bike. What type of riding do you plan to do?

    I ask because those older square taper spindles are heavier, and flexier than modern shimano hollow-tech, Sram GXP, or comparable designs and I think you're making a big compromise there just to get to an 18t granny ring. There might be other ways to get to a granny that's almost this small that don't require you to go square taper. If you're used to that 18t granny on your old bike, are running 8sp, 9sp, or 10sp in back? 9sp and 10sp allow a larger tooth 1st gear in the rear cassette, perhaps allowing you to get to the same gear ratio you're used to on your current bike.

    External bearing BB's are stiffer, lighter, and stronger than the old square spindle types by moving the bearings further outboard and allowing them to be larger diameter, supporting a larger hollow crank spindle.

    Also, modern 3x cranks are typically spaced for a 9 spd or 10sp chains, are those Mt Tamer spiders spaced for 9sp or 8spd? You might want to verify that you won't have problems getting to the middle ring with a narrower 9sp/10sp chain.

    Thirdly, by extending the spindle you're also shifting the entire chainline outboard a little, which might cause drivetrain issues - i.e. stuff like, on the big ring, you'll be a little outboard of where you want to be, such that the chain drags on the inside of the front dir when in the 3rd or 4th cassette cog. It might not be a big deal but it could take some gear combos out of the mix for you.

    So.... to summarize:
    For XC riding, I think you'll want to go with the current standard for compatibility reasons, as well as the fact that you'll notice the stiffness of these newer cranks (for lighter weight)

    Fox AM riding, you'll probably have a hard time finding a square spindle crank that will hold up to the punishment.

    So this might be the bike gods encouraging you to modernize

    Hope that helps!
    Dave

  3. #3
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    Quote Originally Posted by phoenixbikes View Post
    press-fit bb like the one found on the Giant Anthem ?
    I know of no bottom brackets that have a tapered axle and fit BB90/92 press fit frames.

    If it's a BB30 frame then you can fit threaded adapter cups, then run a normal bb in the adapters.

    But for the press fits used by giant you are pretty much limited to external bearing/two piece cranks.

  4. #4
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    Possibly 3 piece square taper bottom bracket and a PF30 adapter would work?
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    Last edited by tkrowe; 12-18-2012 at 09:47 PM.

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