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  1. #1
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    front derailleur rubbing issue

    I have a new to me KHS AM1000 (2006) and in the process of tuning it up I find the front derailleur (SR SUNTOUR) not shifting reliably to low gear especially when the rear (SRAM X-7) is on a higher (smaller) gear. As far as I know everything is stock on this bike.

    Inspection reveals 2 things:
    1: if it does shift the chain rubs on the lateral side of the front arm (side toward the big gear) when on the highest (smallest) rear gear.
    This is minor and I might can twist the unit just a tad.
    2: If the rear derailleur is in 4 or above (smaller gears) it rubs on the bottom of the front arm. This is the major issue.

    There is no adjustment that will move the bottom of that arm lower that I can see. It almost appears that the arm is not made for this gear arrangement.
    The arm appears parallel to the gears.
    There is no more movement left between the derailleur and the frame - The screw is at the point where any CC turn will start to move it out.
    The outside limit screw appears to be right since there is no issue with that.
    The arm is as close to the top of big gear teeth as it can be.
    When in highest gear the tension arm is fully extended.

    Is there a way to stop the chain from riding on the derailleur arm?
    thx

  2. #2
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    Sounds like you might be cross chaining if you're on the small gear front and back.

  3. #3
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    Quote Originally Posted by unaware View Post
    Sounds like you might be cross chaining if you're on the small gear front and back.
    Don't know what that means.
    How does it relate?

  4. #4
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    Yes you're cross chaining.
    It's not unusual, especially women and children have problems understanding the complexity of a 3x9 drivetrain.

    To ease things up I'd get rid of the front derailleur and run a 1x9 setup, it will remedy the issue.

  5. #5
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    Quote Originally Posted by Steel Calf View Post
    ...women and children have problems understanding the complexity
    ...really?

    Ruggb: cross chaining is when you have the chain in a big-big or small-small combo, making the chain go across from one side of the front gears to the other side of the back gears. It's considered poor form, and will wear your drivetrain out faster, as well as often rubbing the front derailleur. There is overlap between the gear ratios anyway, so if you have everything adjusted correctly and the front is rubbing, you should probably shift up in front and down multiple steps in back, or vice versa.
    Riding a Brooks saddle mounted to Reynolds 853

  6. #6
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    if someone already deliberately shifts into small/small or large/large gear combinations and creates a thread based on the resulting problems maybe visiting a bike store for once in a while is the best option around.

    It's not like as if there's no explanation about cross chaining on the internet available either...

  7. #7
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    Quote Originally Posted by Steel Calf View Post
    if someone already deliberately shifts into small/small or large/large gear combinations and creates a thread based on the resulting problems maybe visiting a bike store for once in a while is the best option around.

    It's not like as if there's no explanation about cross chaining on the internet available either...
    there is always at least one person to make newbees feel unwelcome. Thank you

  8. #8
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    Quote Originally Posted by ruggb View Post
    there is always at least one person to make newbees feel unwelcome. Thank you
    No offense meant but sometimes it's not a shame to actually speak with someone knowledgeable in person. Bring your LBS a sixpack after hours and and everything will be eplained and fixed in an instant.

    And maybe next time try a little harder and at least post your inquiry in right sub forum, it's called "Drivetrain - shifters, derailleurs, crank"

  9. #9
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    Hey ruggb, we all were newbies once. Welcome to the forum and enjoy your stay.

  10. #10
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  11. #11
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    Best solution I've found for front derailleur issues is a 1x setup.

    Sent from my XT1575 using Tapatalk
    "I may be old and fat, but at least I'm slow." - Me


  12. #12
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    If the 1 by is not wide enough, a 2 by system can reduce the rubbing issue as well (I'm assuming you currently run a 3 by). You could put a bash guard on the outside and just use the two smallest gears up front to save $$.
    BTW, this wasn't a stupid question.

  13. #13
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    thx to all. Now I know what cross chaining is.
    I have a number of 21 gear bike - never had an issue with any of them. My wife just got a used Trek 4500 and has no issue with 24 gears rubbing anything. However, this KHS - which is labeled an ALL MOUNTAIN bike (which is why I originally posted here) beside having the cross chaining issue has the chain rubbing on the bottom of the derailleur (which was the issue of this post) and technically, I don't think that is actually a cross issue. It rubs because the front gear is so small it needs a big gear in the rear to lift it high enough to clear the bottom part of the derailleur. Or the derailleur is not appropriate.
    Anyway, sticking to not using the higher ratios with that gear will solve that issue as well as any cross chaining, which obviously, is severe with a 9 gear cassette.

    now for a little technical humor - I found this in Reader's Digest
    Why is it that if the Earth had no atmosphere we would not observe any meteors?

    scroll down





    read just the caps
    WdsfEe pgsWOldasULdgvbD ALL BrtE rtDEldgmAD.

  14. #14
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    Quote Originally Posted by ruggb View Post
    My wife just got a used Trek 4500 and has no issue with 24 gears rubbing anything. However, this KHS - which is labeled an ALL MOUNTAIN bike (which is why I originally posted here) beside having the cross chaining issue has the chain rubbing on the bottom of the derailleur (which was the issue of this post) and technically, I don't think that is actually a cross issue. It rubs because the front gear is so small it needs a big gear in the rear to lift it high enough to clear the bottom part of the derailleur.
    You're supposed to shift into a bigger cog when running in the smallest chainring front, if you're not you're basically cross chaining once again. (logic behind a drivetrain?)

    Cross chaining is not an issue of the bike, it's a users fault, I could easily cross chain a 10000$ bike and cause the same issues so don't blame the bike for it.

    Maybe you wanna switch bikes with your wife, hers is obviously working at any chain combination so let her have the headache.

  15. #15
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    U obviously are not married.
    I would then have a bigger headache.
    Yes it is cross chaining as is my wife's even though her's is not rubbing on anything.
    since cross chaining mostly refers to the fact that the chain is coming off/going onto the sprocket at an angle I wasn't expecting it to be running on top of the derailleur bottom brace. anyway onto adjusting the fork.

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