fantom cx crank & gear question's- Mtbr.com
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  1. #1
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    fantom cx crank & gear question's

    i just got a fantom cx about a month ago, the last couple of rides I noticed a pop sound
    at the top of the non drive side of the crank revolution, it doesnt happen when I take my foot off the pedal and it doesnt do it all the time, but it is concerning me.
    it has a truvativ touro crank set on it now. if its something bad wrong with the crank what would be a good upgrade ?
    also mine has the 8 speed rear cassette and the newer ones have 9 speeds, the componets sound the same sora front /tiagra rear , sora flight deck shifters and the frames look exactly the same.. even the paint.. what would I have to do to upgrade to a 9 speed? just change the cassette and adjust the rear derailer? is there a simple change for the shifter from 8 to 9sp?
    Thanks for any help.
    2008 Haro F24(sold)
    2008 Specialized RockHopper(sold)
    Motobecane Fantom CX

  2. #2
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    Have you checked to make sure everything is tight? It sounds like something is loose, or not torqued properly.
    2015 Niner Jet 9 Carbon
    2014 Focus Raven 27R
    2017 Lynskey GR250
    2016 Niner BSB
    1987 Haro RS1

  3. #3
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    i have checked it, a few times over the last couple of days, I can get off the bike spin the pedals and it wont do it at all , it only does it when I am going pedaling forward with my left foot firmly on the pedal., i can padel backwards and nothing, i have thought it was just the pedal a few times i can feel it in my foot when it pops but i spin it and it seems to spin freely. i dont have a clue..
    2008 Haro F24(sold)
    2008 Specialized RockHopper(sold)
    Motobecane Fantom CX

  4. #4
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    I had the exact same problem with my crank. Take off the left crank arm and clean the crap out of the axle contact area and the crank arm itself with WD40 or something. Then put it all together and tighten it properly. Mine is good and quiet for over a month now. I had a tiny bit of black gunk on mine and normally I wouldn't think much of it, but it was causing a lot of creaking somehow. Cleaning it out helped.

  5. #5
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    I will give that a shot, it will be a day or two but I will let ya know what happens. Thanks
    2008 Haro F24(sold)
    2008 Specialized RockHopper(sold)
    Motobecane Fantom CX

  6. #6
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    trick for taking the crank arm off? I took out the bolt/allen head, looks like the arm should just slide off but its pretty snug, whats the trick i didnt want to bang on it and ding it up. is there a puller or something I need or should It come on off easy? Thanks
    Last edited by lhazc; 08-17-2010 at 07:15 PM.
    2008 Haro F24(sold)
    2008 Specialized RockHopper(sold)
    Motobecane Fantom CX

  7. #7
    AZ
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  8. #8
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    Thanks, that site will be helpful
    2008 Haro F24(sold)
    2008 Specialized RockHopper(sold)
    Motobecane Fantom CX

  9. #9
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    If its the stock Truvativ crank, I would just upgrade it if you have the money to do it. I had trouble with the cheap one that came on my Fantom Trail. Bikeisland.com has a upgrade of the stock crank for around $80 shipping and bottom bracket included. But hopefully the crank is just dirty. Goodluck!

  10. #10
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    it is the stock crank, I know nothing about bicycles, if it were a dirt bike I could change just about anything, my sons used to ride/race MX some, but with bicycles im lost. what are the specific things I need to look at to make sure a new crankset will fit? when Im looking online or ebay for a new one?
    near as I can tell this is what I have

    Crankset TruVativ Touro Cross aluminum arms, TruShift 36/50T Chainring, 110BCD
    Bottom Bracket TH sealed ball bearing S-taper

    I wouldnt mind going to like a 40/50, 42/50,42/52 or something close to that.

    how can I tell what I can upgrade to? and what is 110bcd?

    MTBERMISS,
    is the one on bikeisland you mention the FSA omega double?
    Thanks
    2008 Haro F24(sold)
    2008 Specialized RockHopper(sold)
    Motobecane Fantom CX

  11. #11
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    sorry found the BCD.. bolt circle diamater. for changing chainrings im guessing...
    are bottom brackets all the same? are there different lengths for the spindles?
    2008 Haro F24(sold)
    2008 Specialized RockHopper(sold)
    Motobecane Fantom CX

  12. #12
    AZ
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    Quote Originally Posted by lhazc
    sorry found the BCD.. bolt circle diamater. for changing chainrings im guessing... Yes .
    are bottom brackets all the same? No . are there different lengths for the spindles?Yes . Match up to your existing crankset .

    ..............

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