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poping sound

Discussion in 'The Shop' started by tubs26, Feb 14, 2013.

  1. tubs26 New Member

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    ok so when I pedal and get to a certain rotation on the cranks the back cog like pops loud. it's not the chain not lining up, i thought it was the chain its self. well i take it in, and the guy says the chains practically brand new. and I was like well what else could it be? he said he had no clue, also mentioned the cogs should be replaced soon but that was not what was causing it. I said like 15 times when you RIDEthe bike it makes the sound. so what does he do? he puts it in the stand and spins the pedals. and after 5 min says he cant hear anything. now I have nothing against the man, he is nice. anyways, when you have pressure on the pedals it pops and only when. you can spin the wheels for days and nothing will make a peep but once you sit on the bike and ride it, it sounds like it's backfiring. any clue what it is?

    i still think its the chain. i think a link is stiff and when the pedals get to that certain point the cranks pull the chain tight and the chain snaps back into straight giving the cog slack for like a millisecond before it gets tight again and makes that poping sound by pulling the cog back to tension if that makes sense.
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  2. Burnt-Orange New Member

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    I would check to make sure the free hub is also not the cause of the sound
    what kind of hub do you have
    it could be on the way out
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  3. tubs26 New Member

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    I have no clue. it a stock norco scrambler hub, the noise is driving me F**KING CRAZYYYYY!!!
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  4. HardtailHack used an iron once

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    Hmmm, not sure, the urban dictionary describes poping as-

    2.poping
    An act of Catholic paedophillia
    'that guy should be locked up! he was full on poping that kid!'


    If it is a stiff link you'll see it when you backpedal, the mech will move around a little bit when the stiff link moves through it.

    Is your hanger bent? That can cause problems like this, doesn't take much of a twist to mess things up.
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  5. tubs26 New Member

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    the chain is practically new, i oiled it up and ran a rag through it and bent the chain in like every different way and I didn't feel a stiff link. when I went to the bike shop and asked if the hanger needed to be straightened he said it was fine, and it is ok but probably could use a straightening. ill take it to another bike shop and see what he says.
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  6. daisycutter Active Member

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    PoP sounds make me think bearings, pedal.BB, rear hub?
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  7. rockofullr confused

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    Is it more of a creak or more of a pop?

    Can you feel the chain slipping when it happens?

    Does it happen when seated and when pedaling out of the seat?
    (I once had a mystery creak that bothered me for a week and then turned out to be a creaky seat rail due to a loose bolt on the seat post)

    Does it happen in every gear?
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  8. tubs26 New Member

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    it could be the BB but it sounds like its the back hub.

    It's more like a pop. it happens in every gear and happens when I'm pedal standing or sitting. it happens more when I pedal hard it does it loud. the chain Don't slip, instead the back wheel sorta jerks and feels like it flexes. its like every time it happens it seems like something else could be the problem. ill look harder now and see because its beautiful out and I need to ride!
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  9. OGRipper Active Member

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    NORCAL is the hizzle
    It sounds like you've got a freehub problem. You might just have a stickey pawl. Try squirting some lube into the freehub body, at the axle and behind the cassette.

    Also, take a look at your derailleur pulleys. If one was somehow damaged or excessively worn it might create what you describe (and they're also a cheap fix).

    But just to be sure, check your chainring bolts, bottom bracket cups, crank bolts, and cassette lockring. Those shouldn't create jerking you describe, but any one of those can create annoying noise. You might also try another pair of pedals for the same reason, but again those won't really create jerking.
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  10. rockofullr confused

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    I agree with this diagnosis.

    Sounds like it's time for a freehub inspection/rebuild.

    What hub are you running?
    #10
  11. tubs26 New Member

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    ok, ill go to the bike store and see what he says if I cant find out anything, this time a different one...
    the pedals are like a week old and I have had the same pedals before for a few months and nothing of this sort had happened. I do believe it is the freehub because it sounds like it's behind the cassette. like in the hub. as I stated above I dont know what hub it is. its a stock norco scrambler bike with stock wheels and hubs. it has went away for the most part. I just went on a ride and it only did it like 35 times MAYBE. it is still something to look into, it wont heal its self.
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  12. OGRipper Active Member

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    I'm telling you, try squirting some lube in there before you pay someone to check it out. Especially if it's old, you ride in wet conditions, or you regularly use a hose to clean your bike. Freehubs are neglected by everyone and they get sticky over time.
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  13. tubs26 New Member

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    Ok I did that, I strayed (sorry guys) WD-40 in there (its all I got) and layed the bike on its side for a few hours and let it sit over night. I will test it out today for sure...
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  14. Jm_ Active Member

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    Sometimes when you put a new chain on a bike with an older cassette, it has to "mesh" a bit and skips a little at first. Of course, sometimes you ride a bike well past when you should have replaced the chain, and the new chain skips all over the place on the old cassette and you have to replace the cassette because you should have replaced the chain earlier. Riding very hard, like every other day, 3-4 months can be a reasonable amount of time to replace the chain. The same thing happens to your front rings as well, usually not as fast as the rear cassette, unless you use the granny gear all the time.

    A "pop" with no skip is probably a bearing or moving part flexing, such as the in the hub, bottom bracket, or freehub. This usually worsens with time and could be causing a bearing to ovalize it's receptacle. If you are lucky though, the bearing just self-destructs and can be replaced. Some of the cheaper freehub mechanisms can't be replaced and you have to get a new hub, but most shimano stuff is an easy switch-out for not too much $$$. I would usually get up to two seasons on those with pretty hard riding. Sometimes as little as one season. I was pretty good at stripping out freehubs, even dual-pawl types and the star-ratchet system that DT uses. That can definitely cause a "skip" (and a pop sound when it does it). This is usually past the point of fixing, but somehow getting some WD 40 in there may not be all that bad if it's really a sticky pawl, but then it needs grease and lube, otherwise it will self-destruct. Otherwise, only use WD 40 on a bike if you are going to follow up and grease/lube whatever part immediately after. WD 40 is not a lubricant and moving parts need lubricants. Sticky pawls usually only happen if a bike has set for a while and the grease has started to gum up. Usually fairly rare in my shop experience.

    Derailers are usually unlikely candidates here, they will usually be mis-shifting if making any noises, and that is noticeable. Could always be some crazy stuff that is sometimes overlooked, like a cracked bearing race, cracked dropout/frame, etc.
    Last edited: Feb 17, 2013
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  15. tubs26 New Member

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    ok, I'll get to taking the BB apart. today it popped and they way it felt, its felt as if it was the crank arms. i think i might just be a loose chain ring... I'll get on it.
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  16. smittybit New Member

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    I'll back up Jm's post, cassette and chain wear together, so a new chain on old cassette will often do this. If the cassette is pretty worn I'd start by replacing that first, and giving both a bit to mesh.
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  17. Straya Member

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    I'm with Jim and Smittybit. Old cassette and new chain means that the chain doesn't sit in the grooves of the cassette properly and occasionally climbs out of the groove and slips to the next tooth- especially under load. Its only a small distance so it doesn't feel like the chain is slipping but it is a little bit.
    #17