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  1. #1
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    Please look at these pics and tell me why this chainring is misbehaving. shark teeth?

    Hello everyone. I just replace the chain on my Blur. I'm generally a high cadence spinner, but I do ride in very sandy conditions. My chain appeared to be stretched less than 1/16", but I decided to replace it anyway since it was a year old. This is the bikes first chain. In the pic, 12" should fall on the edge of the outer plate, so you can see it aught to have a little wear left in it still.

    I replaced it with a new dura ace/XTR chain. In the granny and big gears, it seemed to working fine in my parking lot test ride. However, in the middle ring the chainring would yank the lower part of the chain around on every pedal stroke, causing all sorts of torment to my rear derailer. If I apply the rear brake and torque the crank I can see the lower part of the chain sort of jump outwards on the chainring. However, this chainring doesn't look too worn to me. What do you think the problem is?

    BTW- these are octalink LX rings.
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  2. #2
    Over the Hill
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    Dreaded chain suck!

    Here is a link that will tell you more than you ever wanted to know about chain suck. But it sounds like you need a new middle ring.

    http://www.fagan.co.za/Bikes/Csuck/OVERALL.htm

  3. #3
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    could it be a stiff chain link, you said you replaced the chain, the link where you connected the chain might need worked side to side until free.

  4. #4
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    Well, I used a Shimano Dura Ace / XTR chain, but I put it together with a SRAM Powerlink, so there shouldn't be any stiff links. Also, it works OK in the big and granny rings.

    I don't know...that middle ring doesn't look all that bad to me though. Weird.

  5. #5
    nnn
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    To me the middle ring looks very bad, it's wider than the big ring and it's supposed to be narrower like the granny compared to ring 2.

  6. #6
    mmm, carbon
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    Quote Originally Posted by nnn
    To me the middle ring looks very bad, it's wider than the big ring and it's supposed to be narrower like the granny compared to ring 2.
    Ever heard of perspective?

    Seems perfectly fine to me. Maybe a little wear but nothing that would cause chain skip.

  7. #7
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    Hey guys. I was looking at my chain this morning, and there is some "shark finning". The picture, as it turns out, as at the section where I'm generating the least torque (6 & 12). Right under the cranks there are a few teeth with a definite curve to them. Also, the casette has some teeth that are starting to look pretty vertical on their faces, and there are little flashes of metal around some teeth, probably fromt he occasional hard shift. It probably doesn't have much wear left. I should probably take off that XTR chain and put on a cheapie, eh?

    So, why do you think I have so much wear with so little chain stretch? Guesses?

  8. #8
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    I think you answered your own question about the sand thing.

    I HATE SHIFTING PROBLEMS; one the reasons I singlespeed. That said, at 2,800 miles I replaced the chain on my 5-Spot. I just went ahead and replaced the XT cassette and middle ring at the same time. Too much money for a XT middle ring, so I went LX for $16.00.

    Besides inflecting harm to the rider, chain suck can cause severe damage to your drive train. It falls in the “you can pay me now, or you can pay me more later category”.

  9. #9
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    Quote Originally Posted by dstepper
    I think you answered your own question about the sand thing.

    I HATE SHIFTING PROBLEMS; one the reasons I singlespeed. That said, at 2,800 miles I replaced the chain on my 5-Spot. I just went ahead and replaced the XT cassette and middle ring at the same time. Too much money for a XT middle ring, so I went LX for $16.00.

    Besides inflecting harm to the rider, chain suck can cause severe damage to your drive train. It falls in the “you can pay me now, or you can pay me more later category”.
    Well, I just got a new middle LX ring at the LBS, but I had to pay $27.50. Where'd you get them for $16 dstepper? They are $23 at Performance!

    Turns out there were 6 teeth on the ring that were particularly shark finned- the two teeth above every shift ramp. I guess I must've had too many hard shifts. That doesn't explain why it worked with the old chain but not the new though. Anyway, it pedals fine now with the new ring.

    Here are some pictures comparing the old ring to the new. One is a side-by-side, the other overlapping. You can't really appreciate how much material is missing until you see the overlapping shot. I still don't get how my old barely-stretched chain was working fine on this ring.
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  10. #10
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    Rainbow Cycle in Laguna Beach had one. That was over a year ago and he probable had for some time.

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