Clonk!

Discussion in 'Tech/Mech General' started by Dodgey, Sep 29, 2009.

  1. Dodgey

    Dodgey Funster

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    Any clever bike types here???:thumb:

    This is the bicycle bike, most of the time the faster/more load applied to the peddles produces a rythmic CLONK (caps 'cos it's loud!) that sounds kinda like some loon following me a belting the frame with a lump hammer.

    It sounds most like it's coming from the rear gear assembly, 7 speed/gears and I can feel it through the frame but nothings touching/fouling anywhere. Bikes only a couple of years old, any thoughts?
     
  2. Terry

    Terry Funster

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    Hi it sounds like the gudgeon pin is loose or worn (holds pedals in position) take off the pedal arms examine grease and replace.:thumb: of course I could be wrong :Rofl1:
    terry
     
  3. Geo

    Geo Trader - Funster

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    First point of call is the pedal crank bearings, rock pedals to test, there should be no play, even if there is no play it could be the early signs of bearing failure, play will eventually become evident, cant think of anything else that would cause a heavy CLONK as you describe
    Geo
     
  4. Andy 01424

    Andy 01424 Read Only Funster

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    Or the Chain is slipping on the gears if this happens during change and keeps trying to go to nex gear:thumb:
     
  5. Dodgey

    Dodgey Funster

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    Terry,

    Gudgeon pin?....Cotter pin, it's the other type (can't remember what it's called) but no can't be that, mad push biker in my youth and remember the cotter pin shenanegans well, one bike just ate 'em, never did figure out why...

    Geo,

    Crank bearings, doesn't sound as though that's where the problem is though I must admit that was my first choice. No decernable movment as yet, might have to bite the bullet and strip the bugger and see. It's only a cheapy but I don't really want to replace at the mo, still seeing exactly how much use it's going to get as to how much to spend next time, that and have you seen modern bikes, hydralic disk brakes, 27 gears, adjustable suspension, toys toys toys:thumb::Rofl1:

    Cheers for the replies guys, any more?
     
  6. Dodgey

    Dodgey Funster

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    Good idea but no chance, anal here has the gears set perfect, no slip and bang on adjustment.
     
  7. johnsandywhite

    johnsandywhite Read Only Funster

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    :Smile: Hi Dodgey. I have the same problem with the Mountain Bike I bought from Walmarts 4 years ago. It has almost always done it. I believe it is the Crank Bearings. When I run Oil into the Crank it quietens down for a period before the sound returns. :RollEyes:
     
  8. Terry

    Terry Funster

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    Gudgeon pin?....Cotter pin :Rofl1: OK I will settle for cotter pin :thumb:
    either way it looks like you are going to have to strip it down :Rofl1: like it or not :Doh:
    terry
     
  9. old-mo

    old-mo Funster Extra Special Life Member

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    If it is more or less every revolution of the peddle,, most probably what used to be the cotter pin,,, but on modern bikes you have an allen key on the end of the shaft (Pedal crank arm),, these are splined or square,, might need nipping up,, if it is the spline type whip it off as if it has been doing it for any length of time a splines might be worn on crank arm,,

    Modern bikes the cranks are alluminium and the shaft is steel,, hence the splines being/getting worn.

    The other alternative, on your gear wheel/cluster,,, if it happens in a particular gear,, it may have a crack on the thread on one particular gear wheel... 5/6/7 gears are made up of individual gears/teeth and they in turn are threaded onto a rachet body,, so you can remove sets of gear teeth and put what ever combination of gearing on that suits you,,
    If I remember correctly the threads are the oposite of the norm,, so as you do not unscrew when peddling.. bear this in mind if it is this and when replacing gear,,

    Think they are that cheap if it is this probably not worth the bother and just buy a new complete set..
     
  10. old-mo

    old-mo Funster Extra Special Life Member

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    No there not,,, "Normal Thread" :Doh:
     
  11. mondo

    mondo Read Only Funster

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    Remove the pedal crank and check the spindle you possibly have a cracked spindle..if not pack it with grease that should cure it
     
  12. Frank772

    Frank772 Read Only Funster

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    May be worth looking to see if the L/h crank is bent (by dropping the bike) and
    hitting the chain stay.
     
  13. johng

    johng Read Only Funster

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    seems a harsh way to check that, Frank :BigGrin: welcome

    I would have said bottom bracket bearings, or what is now in place of the gudgeons, usually a square shaft that now has worn cranks on..

    as said above a few times :RollEyes:
     
  14. John H

    John H Read Only Funster

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    It could be a damaged or kinked link on the chain, or a damaged tooth on the crank?

    John
     
  15. Frank772

    Frank772 Read Only Funster

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    Sorry I should have written caused by dropping the bike
    :Blush:
     
  16. johng

    johng Read Only Funster

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    :BigGrin: no worries

    sorry for being silly :thumb:
     
  17. pappajohn

    pappajohn Funster Life Member

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    chuck it in a skip and buy a TOAD !!!!!!!! :Rofl1::Rofl1:
     
  18. Geo

    Geo Trader - Funster

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    Welcome to the FUN site Frank, it made me smile, written like a seasoned Funster :thumb:
    Geo
     
  19. Frank772

    Frank772 Read Only Funster

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    Thanks Geo, I've also remembered that a gudgeon pin holds
    the piston onto the conrod :Doh:
     
  20. cyclingdoglucy

    cyclingdoglucy Read Only Funster

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    bottom bracket

    just a educated guess is that the bottom bracket wants removeing & a sealed bottom brkt put in its place. you will have to remove the cranks & one of the bottom brkt cups has a left hand thread/:Doh:
     

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