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Thread: Cog Fail

  1. #1
    veinte nueve pulgadas
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    Cog Fail

    Instinct told me when I first saw the 2 piece cogs that something was wrong w/ em. To a pseudo-minimalist, it just seemed unnecessary and destined to fail. However, when the time came for me to put my fingers on a steel 21t cog, and there was an HBC 2-piece in stock, I figured...what the hell, I'll give it a whirl. It was pricey, but blingy too. And after all, cogsets are riveted together, and they seem to work well enough.

    I've been running the 21t 2-piece since ~mid-September, and it is toast. The steel is basically caving in on itself near the riveted arms (imagine a pentagonal cog). I'm glad I caught it before it failed catastrophically.

    It may be that the smaller sizes work well, but this was a disaster. I got ~2.5 months out of a ~$60 cog. At least there was no 6+ month wait for it.

    Buyers of 2-piece cogs: be warned.

  2. #2
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    Pictures please.

  3. #3
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    Glad I didn't get one of those. Deys shore purty, dough.

  4. #4
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    Regular cogs fail too...


  5. #5
    veinte nueve pulgadas
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    Quote Originally Posted by Econoline View Post
    Pictures please.
    as you wish. not a great pic, but you get the idea. as you can imagine, the tooth profile is all sorts of wonky where the thing is flattening and wrapping around the arm.
    Attached Thumbnails Attached Thumbnails Cog Fail-bad_cog.jpg  


  6. #6
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    Whoa!

  7. #7
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    There is nothing wrong with that cog, it is just a new Rotor rear cog.

  8. #8
    one chain loop
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    everything sucks but my vacuum cleaner.

  9. #9
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    I thought Dan was shipping these cogs out like that to offset the out of round chainrings he was producing.

  10. #10
    veinte nueve pulgadas
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    Damn. Should have done better research.

  11. #11
    one chain loop
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    It will be a good christmas tree ornament
    everything sucks but my vacuum cleaner.

  12. #12
    Big Gulps, Alright!
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    Quote Originally Posted by fryed_1 View Post
    Regular cogs fail too...

    That looks like a single sprocket pulled out of a cassette, which isn't nearly as beefy as a SS sprocket.

  13. #13
    gran jefe
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    Quote Originally Posted by Spinning Lizard View Post
    There is nothing wrong with that cog, it is just a new Rotor rear cog.
    That's like Biopace, but for cogs, right?

  14. #14
    Poacher
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    Freyed 1, it looks that was the wrong tool for the job. Scary though. God, that could hurt grinding up a steep hill! nzumbi, I had a 2 part Shimano brake rotor loosen at rivets. I learned my lesson about simplicity. I like the the Stainless steel Chris King cogs these days.

  15. #15
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    The problem is not that it is two pieces. The pins are holding the steel cog to the aluminum body just fine. The problem is that the steel piece is underbuilt. If there were a little more material there, it would be fine. But then people would say that it's too heavy.

  16. #16
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    New product idea for Rotor?


    Edit-
    Damn, I was way late to that party...
    Last edited by rob1035; 12-01-2012 at 11:17 AM.

  17. #17
    veinte nueve pulgadas
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    Quote Originally Posted by icantdrive65 View Post
    The problem is not that it is two pieces. The pins are holding the steel cog to the aluminum body just fine. The problem is that the steel piece is underbuilt. If there were a little more material there, it would be fine. But then people would say that it's too heavy.
    Agreed. Thin, and probably the wrong steel too. Something tells me there wasn't a lot of r&d and engineering with this line of components.

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