Greetings!...and a bottom bracket question- Mtbr.com
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  1. #1
    puts the FU in fun
    Reputation: CuzinMike's Avatar
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    Greetings!...and a bottom bracket question

    Hey guys and gals.

    First off, want to say thanks to the folks on this forum for helping me with my decision to get back into mountain biking after about a 15 year layoff, and especially for helping me with my decision to purchase a Fantom Pro SL 29 a few months ago. My last new bike before this was a '95 Cannondale M500, and needless to say, it's pretty amazing how far bikes have come in the last decade, and I've been having a blast getting reacquainted with the sport!

    Anyway, I've put about 10 solid trail rides on my Fantom, and it's recently developed a "grindy" feeling that seems like it's coming from the bottom bracket. I'm not really familiar with exactly how this bike is spec'd out, or how to work on modern stuff. I'm assuming the BB is a Truvativ GXP, correct? And if so, is it serviceable? I've ridden in some sandy conditions lately, so I'm guessing that's the culprit, but not sure if I can do anything other than replace it? Thanks.

  2. #2
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    The bottom bracket is serviceable, but its not easy. You would need to press the bearings out of the cups (you will need a bearing puller tool). Then you can remove the dust seals, clean and lube the bearings, replace the seals and press them back in the cups. If you can't or don't want to remove the bearings, you can try to just remove the outer seal and clean and lube them and then replace the seal.
    2015 Niner Jet 9 Carbon
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  3. #3
    puts the FU in fun
    Reputation: CuzinMike's Avatar
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    Thanks. I've worked on bottom brackets before, but all of my old Park stuff of course doesn't fit. Looks like it's time to buy some new tools ...

  4. #4
    S*it Happens!
    Reputation: Moto Rider's Avatar
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    I had a Fantom elite and it came with those cranks and BB. I ridden that bike for years in the snow, rain and sand. I never had to do anything to them. At one point in time I thought I developed a problem as it seemed hesitant and made some grinding noises. However, it turned out that I needed a new chain.

    After, that it was all good.



    Good Luck!
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  5. #5
    puts the FU in fun
    Reputation: CuzinMike's Avatar
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    I did think it was a little strange that it would go south on me so quickly, but I've narrowed it down as the culprit, and it seems from the reviews of this BB that I'm not the only one. Thanks again!

  6. #6
    Pimpmobile
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    Pull it off and clean it up best you can, the seal plates come off the outer side easily, there's probably just some sand caught between the left arm and the bearing.

    I'm not a real big fan of the GXP design.
    "Fear not the ob-stackles in your path"

  7. #7
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    Be sure to check the teeth on your chainrings. Do you get the grinding in all 3 chainrings? I had a similar feeling, but it turned out a smashed a couple teeth. All I needed to do was bend them back and go over a couple times with a metal file to smooth things out. It's a free fix and worth checking out.

  8. #8
    puts the FU in fun
    Reputation: CuzinMike's Avatar
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    Quote Originally Posted by TwoHeadsBrewing
    Be sure to check the teeth on your chainrings. Do you get the grinding in all 3 chainrings? I had a similar feeling, but it turned out a smashed a couple teeth. All I needed to do was bend them back and go over a couple times with a metal file to smooth things out. It's a free fix and worth checking out.
    I did check the rings, and all seems well. At first, I though it was just rubbing from a derailleur out of alignment, so I checked my high and low limits and that wasn't it either. The grind isn't really noticeable until I put a decent amount of torque on the pedals, so I'm just going to go through the rest of the drivetrain until I track it down

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