Bike chain keeps breaking.- Mtbr.com
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  1. #1
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    Bike chain keeps breaking.

    I have a Specialized P1AM that I bought recently, it is my first (real) mountain bike. I only have probably 10 hours total of riding time on it, and the chain has already broken 3 times. (And usually hurts my leg muscle when it does).

    Why would it be breaking so much? Everything is in tune, its not rubbing on anything. I am a pretty strong guy, and weigh about 230 pounds, but still, I am new to mountain bikes and haven't put this bike through anything harsh, toughest action its seen is some wheelies and short hill climbs, its barely got a spec of dust on it.

    Also, can anyone recommend a chain that is compatible with this bike that is stronger, but still not very expensive?

  2. #2
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    Carl, the problem is likely not the chain. I would have to guess that that you have been shifting under power.

    Once? Could be a fluke, but three times is a pretty good sample. I haven't been as light as 230lbs since I started riding in the mid-90's.

    Most chains are rated at about 200kgf. The SRAM 991 Cross-Step is rated at 250kgf, but if you're breaking a 200kgf chain three times in a short period of time, you'll break that one too. The less expensive chains will hold you just fine if you don't mangle them.

    Learn to anticipate the need to shift so you can give a little 'kick' to your pedal stroke, and then ease off just as you activate the shifter so the shift is accomplished without so much force applied.

    Even little bitty boney fellers can snap chains from less than great shifting technique.

  3. #3
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    My best guess would be that you are changing under load?
    Do you try and shift down when you are climbing to get in a lower gear without slacking off pedal pressure?

    This puts a huge amount of lateral load on the chain as the derailleur tries to force the chain across and up the cassette resulting in the plates of the chain being forced apart and SNAP goes the chain.

    Even at 230lbs it should not be possible under normal riding conditions to snap a chain if everything is in good working order

  4. #4
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    how are u fixing the chain?

  5. #5
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    Well I have very rarely ever shifted under load, just never trusted doing it, doesn't feel like it would be good. I actually do not shift very much at all, only for trail riding, most of the riding I do is just in the yard or in front of the house, and I get it in a gear I like and leave it there.

    The first time I took the bad link out and shortened it, the last time I just bent it back and pressed the pin back in, nice and centered.

  6. #6
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    Quote Originally Posted by carl1864
    Well I have very rarely ever shifted under load, just never trusted doing it, doesn't feel like it would be good. I actually do not shift very much at all, only for trail riding, most of the riding I do is just in the yard or in front of the house, and I get it in a gear I like and leave it there.

    The first time I took the bad link out and shortened it, the last time I just bent it back and pressed the pin back in, nice and centered.
    And there lies the problem.
    Not sure why it broke the first time but 2nd and 3rd were certainly a result of trying to reuse the link pin.
    You simply cannot reuse chain link pins, they are strickly one time use, once out thats it, bin them.
    Go buy yourself a coulpe of SRAM power links or similar or get a hold of a pack of genuine Shimno joining link pins

  7. #7
    Fat-tired Roadie
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    Quote Originally Posted by carl1864
    and pressed the pin back in, nice and centered.
    That would be your problem.

    The P1 AM is a multispeed bike, isn't it? Current multispeed chains go back together with either a special link or a special pin. The original pins are damaged when they're removed, and you can't reuse them.
    "Don't buy upgrades; ride up grades." -Eddy Merckx

  8. #8
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    If it is a new bike there is a small possibility it was a faulty chain. Chains usually break because of wear and bad shifting (under load).

    Either way I think you should buy a new chain and start again. I would no longer feel comfortable riding on your chain after 3 fails.

    I like www.connexchain.com they make many models at different price points and they come with a good quick link.
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  9. #9
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    Also make sure the drivetrain is true. Meaning nothing is bent or at an awkward angle. If you have a LBS change out the chain I would have them check your alignment.

  10. #10
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    Thanks for all the help. I had no idea that the pins were one time use. I'll try getting a fresh pin, or else using one of those sram power links (is there a disadvantage to having too many power links, such as them possibly coming apart?).

    I noticed the last break was in the same spot as the one before it (I had marked it). Unsure about the first break, hadn't marked things at that time, but perhaps it was the same pin breaking each time.

    PS: Since we're on the topic of shifting under load, how bad is it? I would rarely ever do it since it felt wrong, but I had been under the impression it was ok because people would say how more expensive derailers (or whatever they are called) can shift better under load. Sometimes if your on a steep or multi pitch climb, up a dirt hill or something, wouldn't you have no choice but to shift under load, or else get off the bike?

  11. #11
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    This says it well.
    Quote Originally Posted by FBinNY
    FBinNY, could you clarify what you're saying about bad shifting? In the old days, it was usually impossible to shift under load. Now it's possible. In fact, it's easy. Are you saying that although it's easy, it's also risky to your chain?

    Tom, thanks for being the straight man.

    Before hyperglide shifting under load was virtually impossible because the moment the chain dis-engaged from one sprocket, and before it would settle into the new one it would skitter across the top and riders rapidly learned that they had to reduse the chain tension during a shift to prevent that.

    The gated shifting that hyper glide allows the chain to complete a shift in a short section of arc, so the chain would engage the new sprocket while still attached to the old one, with a sharp S-bend in the transition. It's fine if there isn't too much tension, but as the transition zone comes around the cassette towards 12 o'clock chain tension in the upper loop forces it back down deeper on the old sprocket putting tremendous side pressure on the plates and forcing them out on the pins and/or twisting them, before they finally disengage as they come over the top.

    You can see the potential for harm if you put a bike in the stand and do a shift in slow motion and gently hold back the wheel as the shift zone comes over the top.

    So while hyperglide (or gated shifting by any name) has been a great benefit to new riders, making unskilled shifts possible, there's a cost in chain breakage.
    Duct tape iz like teh Force. It has a Lite side and a Dark side and it holdz the Universe together.

  12. #12
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    [QUOTE=carl1864](is there a disadvantage to having too many power links, such as them possibly coming apart?).

    You could run as many as you want I guess but I would think that they are a week point in them selves, but to get you out of a hole then I am sure that 2 or so would be OK

    PS: Since we're on the topic of shifting under load, how bad is it? I would rarely ever do it since it felt wrong, but I had been under the impression it was ok because people would say how more expensive derailers (or whatever they are called) can shift better under load. Sometimes if your on a steep or multi pitch climb, up a dirt hill or something, wouldn't you have no choice but to shift under load, or else get off the bike?

    How bad is it? Very bad, you tend to break chains
    Once you get your climbing technique down you should never have to change under load.
    Note I did not say "Not have to change down"
    First up you should try and select the correct gear for the climb as you hit it and use your momentum from the descent or run in prior for as far as possible.
    If you do need to change down, put in a burst of one or two quick pedal revolutions then take the load off [dont stop pedaling, just relax the pressure on the pedals] and shift down using your forward momentum again to allow you to pedal without load.
    It does take practice and you do need a level of fitness to allow you to put in those extra couple of pedal revolutions to be able to change.

    I would be confident in saying that no experienced rider would ever change down under load and NEVER EVER while standing and stomping up a hill

  13. #13
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    You can change gears under load but don't do it when you are applying a lot of load. The more the load during a gear change the more the chain is worn plus you can break gear teeth. I've done all of this.

    As you get used to riding you will be able to anticipate what gear you need before you get to the base of a hill. If you miss it by one or two gears then you can try to get a short burst of speed up so you can shift down while coasting or under a light load.

    Be careful though because it only takes one really bad shift to ruin your day or maybe the chain will break on the next ride you go on. Chains know when you are at the absolute furthest point from your car and they like to break there so always keep a chain tool and quick link or two on you when you ride. Two quick links is a very good idea because its very easy to drop a part and not be able to find it in the weeds or in the dark. It also gives you an extra for the person in your group who doesn't take any spare parts with him ;-).

  14. #14
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    One other thing that doesn't apply to your new bike, but once a chain gets abused or worn a certain amount its going to keep breaking and will need to be replaced. I got about 800 hard trail miles out of my last chain with no breaks but it was stretched (worn) to the point it was causing skips. Depending on your riding style and conditions and maintenance habits, you may be able to get more than 800 miles out of your chain before you have to replace it.

  15. #15
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    Seems like you may have dropped a link when you fixed the chain....

    So start over get a new chain and a power link...

    Shift the front to the big ring and the rear to the big ring...the RD may be tight but the bike should pedal...

    Don't shift under as much load as you have been shifting.

    Even you miss a shift you can bend a link as well....besure to push the shifter firmly and quickly through its motion.

  16. #16
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    You size new chains without the rear derailleur in the mix. Big ring + big cog +1 full link
    Do not use the biggest 3 cogs on the big ring or the smallest 3 cogs with the small ring. The middle ring shouldn't be used with the biggest or smallest cog. That is called cross chaining, the further from straight a chain is the weaker it is.

  17. #17
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    I think it bears mentioning that the rest of the drivetrain lasts a long time for those of us who replace our chains before they start to skip.
    "Don't buy upgrades; ride up grades." -Eddy Merckx

  18. #18
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    Quote Originally Posted by AndrwSwitch
    I think it bears mentioning that the rest of the drivetrain lasts a long time for those of us who replace our chains before they start to skip.
    Very good point... I should have mentioned that. I had to replace my cassette and rings because of that. Actually, the LBS said I needed a new cassette but I didn't really. I had a broken tooth on the middle front ring that was causing the skip problem.

    None the less, AndrwSwitch is right. Buying a chain gage is worth the small investment.

  19. #19
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    Quote Originally Posted by tshulthise
    Buying a chain gage is worth the small investment.
    You dont need a chain gauge to measure chain wear.
    Save your money and use a 12inch ruler or tape measure, most people will have either or laying around home.

    All bicycle chains have a 1/2 inch pitch when new E.G. 24 links equals EXACTLEY 12 inches.
    Measure 24 links when the chain is tight with no slack, if you have more than 1/8 inch over 12inches then replace the chain.
    This method is not only cheaper than a chain gauge from the likes of Park tools but it measures over a larger length of chain and so gives a more accurate reading than the 4 inches or so a chain gauge measures

  20. #20
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    Quote Originally Posted by jeffgre_6163
    You dont need a chain gauge to measure chain wear.
    Save your money and use a 12inch ruler or tape measure, most people will have either or laying around home.

    All bicycle chains have a 1/2 inch pitch when new E.G. 24 links equals EXACTLEY 12 inches.
    Measure 24 links when the chain is tight with no slack, if you have more than 1/8 inch over 12inches then replace the chain.
    This method is not only cheaper than a chain gauge from the likes of Park tools but it measures over a larger length of chain and so gives a more accurate reading than the 4 inches or so a chain gauge measures
    I think it is worth getting a 12 in metal ruler from Home Depot or somewhere like. Some "plastic" rulers are not very accurate. It is worth measuring your new chain and replace when 1/8 inch longer. That way you are measuring the difference and it doesn't matter if you ruler is "wrong".
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