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  1. #1
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    Bent chainring tooth

    Hello,

    I just recently purchased a Specialized Diverge DSW and within a week, one of the chain ring teeth bent 90 degrees towards the small ring. I took the bike back to my LBS and they said it would not be covered by warranty and shaved the tooth down.

    I only ride on a bike path and have no idea how this would have happened. Pretty disappointing that this would happen so quickly after purchasing the bike.

    2 questions:


    1. Should I contact Specialized directly and see if they will help me out?
    2. Will this affect my bike in any negative way?


    Thanks for your input.


    Bent chainring tooth-chainring1.jpgBent chainring tooth-chainring2.jpg

  2. #2
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    Was it bent when you purchased it?
    If not, why would the LBS or Spec be responsible?

    It would probably effect the shifting, if it occured at that position on the cranking cycle. But since your just on the bike path and not trying to win a field sprint with Cav&Crash, it will probably be ok.
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  3. #3
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    Could it have been slightly bent when I purchased it? Maybe, but it was only on my last ride that I noticed the noise the chain was making when it would catch on the bent tooth. Seems like it would be pretty difficult for this happen on a bike path--if I had been off road or on gravel I could understand...

  4. #4
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    Obviously something happened to it. I would look for other locations for the problem, not on the bike path.
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  5. #5
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    that chainring does not look only a week old.

    Will this affect my bike in any negative way?
    ride it and find out?

    if the chain is skipping, simply buy a new or used chainring. all the info needed to purchase one is the bcd and tooth count.
    Yossarian: don't worry. nothing's going to happen to you that won't happen to the rest of us.

  6. #6
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    Praxis crankset is standard? Bike was sold as new?
    There's sometimes a buggy.
    How many drivers does a buggy have?

    One.

    So let's just say I'm drivin' this buggy...
    and if you fix your attitude you can ride along with me.

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  7. #7
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    If you bought that new recently, (a) you need someone to show you how to shift and ride (b) see (a). How come the derailleur is so scuffed up? It looks like something has hit the outside of the derailleur.
    What details have you left out?
    Attached Thumbnails Attached Thumbnails Bent chainring tooth-chainring2.jpg  

  8. #8
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    Quote Originally Posted by bikerjulio View Post
    Praxis crankset is standard? Bike was sold as new?
    Yes--standard and yes, new.

  9. #9
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    Quote Originally Posted by kiwisimon View Post
    If you bought that new recently, (a) you need someone to show you how to shift and ride (b) see (a). How come the derailleur is so scuffed up? It looks like something has hit the outside of the derailleur.
    What details have you left out?
    Yes--next Wednesday will be 2 weeks. This is my first road bike, so yes my shifting and riding is not great; however, I can't recall anything hitting the derailleur. I actually believe what you are pointing out is some grease that rubbed off and not scuffs, but I will double check when I ride a little later today.

    Again, I don't believe I ran over or hit anything, and as crazy as it may sound, the sound of the chain hitting the bent tooth seemed to just come out of nowhere.

    Should I be worried about the one tooth or is it imperative to purchase and install a new ring?

    Thanks again for any and all input.

  10. #10
    'brifter' is a lame word.
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    Looks older than 1 week...
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    and a bunch of skateboards

  11. #11
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    Quote Originally Posted by cxwrench View Post
    Looks older than 1 week...
    Per above, 2 weeks this upcoming Wednesday (approx. 100 miles).

  12. #12
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    Great if it is grease, I hope so, In that case I would be thinking that while the chain was on the smaller chainring you or some one has inadvertently bumped the larger chainring into something hard like a concrete curb. No, the one tooth is probably not that critical (but you need to check that all your teeth are straight). Looking at the amount of wear on the outer chainring I think you need to look at this. https://youtu.be/C9ZA-4gYpMQ?t=1m2s

    If you get a chance, go on a group ride and tell them you are new and are looking to learn, most cyclists will be happy to help.If you can't do this at least ask the shop if they can help you shift better. This isn't a warranty issue but it is a good teachable moment. Keep asking any other questions you may have. Good luck.

  13. #13
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    Quote Originally Posted by kiwisimon View Post
    Great if it is grease, I hope so, In that case I would be thinking that while the chain was on the smaller chainring you or some one has inadvertently bumped the larger chainring into something hard like a concrete curb. No, the one tooth is probably not that critical (but you need to check that all your teeth are straight). Looking at the amount of wear on the outer chainring I think you need to look at this. https://youtu.be/C9ZA-4gYpMQ?t=1m2s

    If you get a chance, go on a group ride and tell them you are new and are looking to learn, most cyclists will be happy to help.If you can't do this at least ask the shop if they can help you shift better. This isn't a warranty issue but it is a good teachable moment. Keep asking any other questions you may have. Good luck.
    Thanks-- I do try my best to avoid cross-chaining, although as I am new to this, I have accidentally shifted into a cross chain position sometimes (I shift out ASAP).

    I guess the other question is that if I have to pay to replace it myself, is it worth it at this point or should I wait? If replacing it is the best bet, then is it possible to just purchase the big ring (I can't seem to find just the big online)?

  14. #14
    'brifter' is a lame word.
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    Quote Originally Posted by Dbcycle4 View Post
    Thanks-- I do try my best to avoid cross-chaining, although as I am new to this, I have accidentally shifted into a cross chain position sometimes (I shift out ASAP).

    I guess the other question is that if I have to pay to replace it myself, is it worth it at this point or should I wait? If replacing it is the best bet, then is it possible to just purchase the big ring (I can't seem to find just the big online)?
    Don't worry too much about cross chaining, at least big/big. ALL modern drive trains are designed w/ that in mind...it will work on ANY bike. Of course the more you do it, the faster your drive train will wear, but it should work. Small/small is not generally possible w/o some rub.
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  15. #15
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    Not the first time I've heard this story. Not that I believe it "just happened" but I've heard it before from someone with Praxis rings.

    Anyway, contact Praxis and explain. I'm pretty sure Specialized will just tell you to screw without any consideration.....but from everything I've heard Praxis is a stand up company with good customer service. Not to imply they will, or should, cover it though but of the options they'd be your best bet for trying to get help, I think.

  16. #16
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    Quote Originally Posted by kiwisimon View Post
    If you bought that new recently, (a) you need someone to show you how to shift and ride (b) see (a). How come the derailleur is so scuffed up? It looks like something has hit the outside of the derailleur.
    What details have you left out?
    That FD looks mounted way too high IMHO.
    "‘Photograph me on horseback,’ wrote Teddy Roosevelt in 1908. ‘Tennis, no. And golf is fatal.’ "

  17. #17
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    Quote Originally Posted by Marc View Post
    That FD looks mounted way too high IMHO.
    Ditto
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  18. #18
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    Quote Originally Posted by Jay Strongbow View Post
    Not the first time I've heard this story. Not that I believe it "just happened" but I've heard it before from someone with Praxis rings.

    Anyway, contact Praxis and explain. I'm pretty sure Specialized will just tell you to screw without any consideration.....but from everything I've heard Praxis is a stand up company with good customer service. Not to imply they will, or should, cover it though but of the options they'd be your best bet for trying to get help, I think.
    In all honesty, I don't know how it happened. I'm not saying it is not my fault, only that I don't know... Just frustrating to have it happen w/n the first 2 weeks and not have a definitive answer as to how.

  19. #19
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    Quote Originally Posted by Marc View Post
    That FD looks mounted way too high IMHO.
    I'd have no idea how to identify the appropriate FD height.

    Could the FD being too high lead to having to double tap the shifter on big ring --> small ring transfer and vice versa? This keeps happening to me A LOT (even before the bent tooth).

  20. #20
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    Quote Originally Posted by Dbcycle4 View Post
    In all honesty, I don't know how it happened. I'm not saying it is not my fault, only that I don't know... Just frustrating to have it happen w/n the first 2 weeks and not have a definitive answer as to how.
    FD looks setup wrong....it over shifted as a result (looks like the bet tooth was next to a shifting ramp/pin), bending the tooth when the chain was forced improperly to derail. LBS ground the tooth down rather than admit their biff.

    For giggles take a photo of the FD over the front chainring (chain on granny cog). Emphasis to capturing how much space there is between the bottom-of-the-outer-plate and the teeth. HINT: it should be only 1mm or so give or take a skoche.
    "‘Photograph me on horseback,’ wrote Teddy Roosevelt in 1908. ‘Tennis, no. And golf is fatal.’ "

  21. #21
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    Quote Originally Posted by Dbcycle4 View Post
    Thanks-- I do try my best to avoid cross-chaining, although as I am new to this, I have accidentally shifted into a cross chain position sometimes (I shift out ASAP).

    I guess the other question is that if I have to pay to replace it myself, is it worth it at this point or should I wait? If replacing it is the best bet, then is it possible to just purchase the big ring (I can't seem to find just the big online)?
    Just as an update, I took the bike out for 20 miles...didn't really notice too much difference with the tooth shaved down and confirmed that it is just grease on derailleur and NOT scuffs.

    Any thoughts on why I have to double tap shifts on ring transfers; is this normal? Could it be the result of the FD mounted too high?
    Last edited by Dbcycle4; 2 Weeks Ago at 04:53 PM.

  22. #22
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    Quote Originally Posted by Marc View Post
    FD looks setup wrong....it over shifted as a result (looks like the bet tooth was next to a shifting ramp/pin), bending the tooth when the chain was forced improperly to derail. LBS ground the tooth down rather than admit their biff.

    For giggles take a photo of the FD over the front chainring (chain on granny cog). Emphasis to capturing how much space there is between the bottom-of-the-outer-plate and the teeth. HINT: it should be only 1mm or so give or take a skoche.
    I will take a pic next time i have the bike out and measure the gap.

  23. #23
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    Quote Originally Posted by Dbcycle4 View Post
    Just as an update, I took the bike out for 20 miles...didn't really notice too much difference with the tooth shaved down and confirmed that it is just grease on derailleur and NOT scuffs.

    Any thoughts on why I have to double tap shifts on ring transfers; is this normal? Could it be the result of the FD mounted too high?
    Yes, if you're referring to front deraillleur shifter. One tap will clear the chain from the cage when in the outer cogs in back. Two taps let it relax a little more, to clear the front derailleur cage when on the inner cogs in back.

    BTW the teeth adjacent to that bent tooth are really worn down. Do you really mash down hard when you ride? Was the bent tooth as worn down as the adjacent teeth? This is evidence of greater pressure around that broke tooth, which could explain why it got bent.

    Heck, I'd take it to the LBS and have them put a new big ring on and adjust the front derailleur. And quit punishing that big gear, cowboy!

  24. #24
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    Quote Originally Posted by Fredrico View Post
    Yes, if you're referring to front deraillleur shifter. One tap will get clear the chain from the cage when in the outer cogs in back. Two taps let it relax a little more, to clear the front derailleur cage when in the inner cogs in back.

    BTW the teeth adjacent to that bent tooth are really worn down. Do you really mash down hard when you ride? Was the bent tooth as worn down as the adjacent teeth? This is evidence of greater pressure around that broke tooth, which could explain why it got bent.

    Heck, I'd take it to the LBS and have them put a new big ring on and adjust the front derailleur. And quit punishing that big gear, cowboy!
    I'm sure I mash fairly hard due to inexperience and that I'm pretty big (not fat). Seems like it would be hard to wear down teeth in a week regardless of mashing...

  25. #25
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    Quote Originally Posted by Dbcycle4 View Post
    I'm sure I mash fairly hard due to inexperience and that I'm pretty big (not fat). Seems like it would be hard to wear down teeth in a week regardless of mashing...
    Well, I'm just going by the evidence in the picture. What's your average cadence and do you mash big gears? That'll do it on a cheap aluminum chain ring, if we can believe the picture. Those teeth look more worn than after the first couple of thousand miles.

    I knew a guy who completely flattened all his big ring teeth. He did it in one season. He was complaining how the chain was skipping. The teeth on the inner cog looked spanking brand new, not even any chain lube residue.

    After that derailleur gets adjusted, you'll be ok for awhile on that ring, but I'd get my "spin" down a little better. Don't always try the hardest gears. Instead increase leg speeds. The drive train will last a lot longer.

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