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My poor crank arm...

PhinxPhinx Posts: 297
edited May 2010 in MTB workshop & tech
Hi guys and girls. I don't post often but an emergency forced me to come in to the world of the living. A few days ago (imbaressed) my crankarm fell of as i was riding. I didnt give it a big thought and just bolted it back on. Yesterday it flew off again and i got really peed of and decided to take a look. To my suprise the bolt thread was gone and it seems the thread inside the bottom bracket is gone as well. How can this be? I only bought it in november last year i started riding it in january?

Not sure what by BB is but it is a Giant Yukon FX3 and the website says it is just a 'cartridge'.
Giant Yukon FX3

Posts

  • The Northern MonkeyThe Northern Monkey Posts: 19,174
    What cranks are they?
    Santa Cruz Butcher
  • PhinxPhinx Posts: 297
    Truvativ ISOFlow
    Giant Yukon FX3
  • nicklousenicklouse Posts: 50,675 Lives Here
    splined or?
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • PhinxPhinx Posts: 297
    Square taper
    Giant Yukon FX3
  • nicklousenicklouse Posts: 50,675 Lives Here
    replace the cranks and bb as the arm will just keep coming off even if you replace the BB.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • PhinxPhinx Posts: 297
    why cranks?
    Giant Yukon FX3
  • hounslowhounslow Posts: 153
    Phinx wrote:
    why cranks?
    chances are it falling off/running loose has worn away at the inside of the crank arm, causing a sloppy fit.
  • PhinxPhinx Posts: 297
    How can they if their have no thread in them? They just go on and a rather wide end of the bolt is keeping them in place by pressing it againsts the BB.
    Giant Yukon FX3
  • ilovedirtilovedirt Posts: 5,798
    Yeah but since you've been riding it while it's been loose, the square taper on the BB and crank arm will no longer be a decent fit, so it will keep coming undone.
    Production Privee Shan

    B'Twin Triban 5
  • PhinxPhinx Posts: 297
    Damn...is it possible for a BB to be so poor that the thread gets shaven off in 3 months? Or is it a defect?
    Giant Yukon FX3
  • nicklousenicklouse Posts: 50,675 Lives Here
    Phinx wrote:
    Damn...is it possible for a BB to be so poor that the thread gets shaven off in 3 months? Or is it a defect?

    with riding on it you will have done the damage.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • PhinxPhinx Posts: 297
    My bottom bracket can't be made of anything metal...it is deffinatelly a paper one...
    Giant Yukon FX3
  • PhinxPhinx Posts: 297
    Dear commnity, do you have any recommendations for my next crankset?
    Giant Yukon FX3
  • supersonicsupersonic Posts: 82,708 Lives Here
    Deore M590. Comes with its own external BB.
    GT ZASKAR CARBON TEAM

    VOODOO CANZO

    Come and see me at https://www.facebook.com/biketyke/
  • ilovedirtilovedirt Posts: 5,798
    Phinx wrote:
    Damn...is it possible for a BB to be so poor that the thread gets shaven off in 3 months? Or is it a defect?
    It's Truvativ, so entirely possible!

    Like supersonic said, the Shimano Deore crankset is very good on a budget and comes with the BB too. The Hollowtech II axle is SO much better than square taper.
    Production Privee Shan

    B'Twin Triban 5
  • lesz42lesz42 Posts: 690
    supersonic wrote:
    Deore M590. Comes with its own external BB.


    +1 great VFM!
    Giant Trance X0 (08) Reverb, Hope Hoops 5.1D, XT brakes, RQ BC, Works Components headset 1.5
  • PhinxPhinx Posts: 297
    I saw a set for £50 on e-bay. Is that an ok peice for a new one?
    Giant Yukon FX3
  • bails87bails87 Posts: 12,998
    http://www.chainreactioncycles.com/Mode ... elID=40496

    http://www.merlincycles.co.uk/mountain- ... inset.html

    Buy from a 'real' shop for the same price.
    MTB/CX

    "As I said last time, it won't happen again."
  • PhinxPhinx Posts: 297
    What about the size of BB? Universal or are the websites forgot to add the options? Plus will there be any facing involved? (whatever that means).
    Giant Yukon FX3
  • Matt 24kMatt 24k Posts: 186
    The Hollow Tech 2 BB comes with spacers to fit either 68 or 73mm frames. You should get the frame faced but a lot of people don't bother.
  • nicklousenicklouse Posts: 50,675 Lives Here
    Matt 24k wrote:
    You should get the frame faced but a lot of people don't bother.
    and then wonder why their bearings did not last that long.

    get it faced.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • stumpyjonstumpyjon Posts: 4,069
    If you buy your crankset from a bricks and mortar shop they may even face the BB shell for you for nothing (or at least discounted0, it's only a 10 minute job really.
    It's easier to ask for forgiveness than for permission.

    I've bought a new bike....ouch - result
    Can I buy a new bike?...No - no result
  • Louis84Louis84 Posts: 135
    Phinx wrote:
    Plus will there be any facing involved? (whatever that means).

    :lol: EXACTLY

    You can tell if your frame has been previously faced as there will be no paint around the BB shell on the drive side of the frame. Although if you owned the frame from new it probably has not been faced.
  • PhinxPhinx Posts: 297
    I'm writing an article on this when i get a chance...i see there are tools for sale to do this in a classic DIY style, but i aint spending that money on a tool i will use a few times in my lifetime...alternatives are bike shops. How do i know if i need it faced or not?
    Giant Yukon FX3
  • Louis84Louis84 Posts: 135
    Phinx wrote:
    I'm writing an article on this when i get a chance...i see there are tools for sale to do this in a classic DIY style, but i aint spending that money on a tool i will use a few times in my lifetime...alternatives are bike shops. How do i know if i need it faced or not?

    i just told you, ninny!
  • PhinxPhinx Posts: 297
    sorry, my bad :D i did not sleep for the past 31 hour. I guess it's starting to show.
    Giant Yukon FX3
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