3rd visit to LBS and still not useful solution.. New chainrings question- Mtbr.com
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  1. #1
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    3rd visit to LBS and still not useful solution.. New chainrings question

    Just got back from the 3rd local shop asking for a solution to my, to me, simple question.

    I currently run a Shimano XT FC-M760 – 3x9 – 175 mm (22/32/42) setup and I would like to update to a 2x set of 24/38/bashguard

    I got some new rings from Jenson the other day but the 38t dont really fit.. same bcd but it wont lay flush on two of the spider arms!! The chainring is for a M785 - i noticed that after a couple of hours trying to figure it out. After some searching I could see some older post with people using a dremel tool on the spider for a mm or two to make it fit.

    Or should I get a universal ring that would fit? I believe raceface would fit?

    Please help me get back on the trails again.


  2. #2
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    Reputation: RustyIron's Avatar
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    If you're buying your parts online and putting them together yourself, why exactly are you going around asking the bike shops for help?

  3. #3
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    Several reason since you ask. I can't wait for the lbs to get parts. All of them mentioned 5 days tt. Also, they don't support my crank any longer I guess. I have supported two of the Lbs before and they encourage diy work.

    Thanks for your comment. Do you want to chime in with a solution for my problem?

  4. #4
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    It seems you've found two possible solutions: wait five days for the shops to get the right parts, or hack away at your crank apart with a Dremel tool. I recommend the former.

  5. #5
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    Quote Originally Posted by RustyIron View Post
    It seems you've found two possible solutions: wait five days for the shops to get the right parts, or hack away at your crank apart with a Dremel tool. I recommend the former.
    Thank you again for your insight. Perhaps there was a 3rd, 4th and maybe 5th solution.

  6. #6
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    I recommend replacing the crank with a 2x specific and selling your current crank on ebay. Probably will need a new front der and shifter as well or just make it a 1x and save some weight by removing the front der and shifter.

  7. #7
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    Quote Originally Posted by LargeMan View Post
    I recommend replacing the crank with a 2x specific and selling your current crank on ebay. Probably will need a new front der and shifter as well or just make it a 1x and save some weight by removing the front der and shifter.
    In most cases a 3x crank is identical to a 2x with a bashring. replacing his existing crank with the same thing doesn't make any sense. same with the derailleur, no need to replace that either, a limit screw adjustment will do just fine.

    OP, either get the right rings or dremel your chainring. Dont dremel your crank. chainrings are replaceable wear items, cranks are more expensive to replace if you mess it up.
    Rigid SS 29er
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    Stop asking how much it weighs and just go ride it.

  8. #8
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    Quote Originally Posted by *OneSpeed* View Post
    In most cases a 3x crank is identical to a 2x with a bashring. replacing his existing crank with the same thing doesn't make any sense. same with the derailleur, no need to replace that either, a limit screw adjustment will do just fine.

    OP, either get the right rings or dremel your chainring. Dont dremel your crank. chainrings are replaceable wear items, cranks are more expensive to replace if you mess it up.
    Thank you very much. Appreciate it.

  9. #9
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    you'll be hard pressed to find a 38 tooth chain ring for the middle position on a 3X crank. What you bought was designed for a 2X crank, and believe it or not the mounting tabs are a bit different which is why everyone is resorting to dremel tools and files. The suggestion to get a 2X crank isn't that odd.

  10. #10
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    Quote Originally Posted by pcmark View Post
    you'll be hard pressed to find a 38 tooth chain ring for the middle position on a 3X crank. What you bought was designed for a 2X crank, and believe it or not the mounting tabs are a bit different which is why everyone is resorting to dremel tools and files. The suggestion to get a 2X crank isn't that odd.
    This... the chain rings are usually specific to the crank and vice versa. Most cranks will only have an "acceptable" range of rings that will be accepted. If you really want to keep your crank that much you pretty much have your solution at hand (finding the proper rings by waiting or by dremeling your current).

    My suggestion would be to go with a used 2x specific crank and go from there. Any specific reason you want the bashguard on the chain ring and not attached to the bottom bracket?

  11. #11
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    It's not that unusual for ring with the same hole centres to not fit on other brands of crank, or even other cranks from the same brand!

    Taking a couple of mm off the inside of the tab on the ring is no big deal and is the simplest thing to do. Just take your time so that you don't remove too much metal. You want the ring to still be a snug fit. Do it right and it'll work just fine.

  12. #12
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    I would modify the chain ring before I started grinding on the crank itself. Shimano has made some cranks and rings over the years that had minor compatibility issues like this. I wouldn't be shocked if a shop wound up ordering a chain ring that needed a little filing to fit.

  13. #13
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    Thanks all! I will work on the ring one of the next days and let you know how it turns out. thanks!

  14. #14
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    All done. Just need to adjust the front derailer and check if I need to loose a few links on the chain


  15. #15
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    Heads up, rotate your bash ring so the thin section is hidden behind the crank arm. As pictured it will snap on the thin section on the first good strike.

    Sent from my Moto G (5) Plus using Tapatalk

  16. #16
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    Quote Originally Posted by Nutball View Post
    Heads up, rotate your bash ring so the thin section is hidden behind the crank arm. As pictured it will snap on the thin section on the first good strike.

    Sent from my Moto G (5) Plus using Tapatalk

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