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  1. #1
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    Chain rubbing against front deraillur after fixing chain...Advice sought.

    My chain broke after a bike accident. I bought a new link, and put the chain back on the bike. Rear deraillur is Sram-x7, can't think of what front is and am quite frankly to tired to go in the garage and look. But the only gear the bike will stay in is 1st, and the chain is dragging against the front deraillur. Did I lose more than one link when my chain snapped? Is my chain now a link short? When I fed the chain back on the rear deraillur I think I went around the smallest areas I could get the chain around, but I may have mixed that up. I'm sorry I sound like such a moron, I have been riding for a while, but was always lucky with the quality of my bikes (Kona the first time, 5-6 solid years) and only had to do basic maintenance, and change tires etc..

    So basically, what does it mean when the chain is rubbing against the front deraillur? Is the chain too short? Did I put it on wrong? I can't find the master-link on the chain, and popping it back off is a pain thusfar. I am probably missing something so obvious because I am just starting to attempt to become a novice bike mechanic, but I would really appreciate any expert advice I could attempt to follow.

  2. #2
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    I don't see how shortening a change can make the chain rub the FD but I'm no veteran.

    Maybe the wreck bent, or otherwise through off the proper adjustment of the FD? I did recently manage to properly adjust mine to perfection without help, take it from, its meticulous and even an 8th of a turn of limit screws can make it rub

    Google parktool.com front Deraillur for a detailed write up and video on how to properly adjust. I found the one on pinkbike to leave out a few important steps.

    Edit: before we get ahead of our selves, check the obvious. Is the link you just put on rubbing or the whole clench of the chain? Are all pins of the chain set properly? Are you certain your chain has a master link? If so you should be able to find it. Good luck.

  3. #3
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    One other simple check is the orientation of the front derailleur. If you went down, you may have banged the FD and twisted it around the seat tube. The outer edge of the FD "cage" should be parallel to the outer chain ring. If it isn't, you'll get rub.

    And, yep, double check the routing of the chain. I'm sure all of us DIY'er have gotten it wrong at one point or another. Just spin the crank backwards (at least four rotations to run the whole chain through) and make sure the chain passes through the RD smoothly.
    Joe
    Chicago, IL

  4. #4
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    Quote Originally Posted by ZmyDust View Post
    I don't see how shortening a change can make the chain rub the FD but I'm no veteran.

    Maybe the wreck bent, or otherwise through off the proper adjustment of the FD? I did recently manage to properly adjust mine to perfection without help, take it from, its meticulous and even an 8th of a turn of limit screws can make it rub

    Google parktool.com front Deraillur for a detailed write up and video on how to properly adjust. I found the one on pinkbike to leave out a few important steps.

    Edit: before we get ahead of our selves, check the obvious. Is the link you just put on rubbing or the whole clench of the chain? Are all pins of the chain set properly? Are you certain your chain has a master link? If so you should be able to find it. Good luck.
    I don't think the wreck had any major effect on the FD. It was an odd crash, I was side tracked by the bottom of one of those larger construction signs which was hidden in longer grass. There was a wall on my right, which I ran into and basically just dragged across for some nice road rash. The chain did not break until I tried to ride away, and it just snapped.

    It is the whole chain that is rubbing, not just the new link. Thx for the route to the instruction.

  5. #5
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    Like I sadi in the previous quote, I do not think I banged the FD. And igf you get the routing of teh chain wrong, does it not usually correct itself? I will mess with it again today, and thank you very much for posting.

  6. #6
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    I'm not sure it takes a big hit to move the FD just slightly out of alignment, so it's worth a look. Press on the pivot point of the FD (to get it to swing out) and sight it from above.

    I went down hard recently and landed on the opposite (left) side. Apparently, that was enough force from the chain, maybe my foot or something to knock the FD just a little bit out of alignment. If there's a spacer/rubber collar between the FD mounting ring and seat tube, it doesn't take an extreme amount of force to rotate the FD.

    As for routing and self-correcting. When you pedal forward, the derailleurs will simply shift the chain into the right gears. Rotating the cranks backwards (once shifted) will highlight any routing errors, kinks, excess dirt, etc in the drivetrain. It should make vey little noise with a smooth chain.
    Joe
    Chicago, IL

  7. #7
    Trail Ninja
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    Are you sure it's the FD?

    Make sure the chain wraps around the pulleys properly in the back. Some novices accidentally route the chain incorrectly around the rear derailleur pulley, running on the outside of the tab.

    Without pics, vids, or seeing it in person, all I can do is guess.

  8. #8
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    Quote Originally Posted by joeinchi View Post
    I'm not sure it takes a big hit to move the FD just slightly out of alignment, so it's worth a look. Press on the pivot point of the FD (to get it to swing out) and sight it from above.

    I went down hard recently and landed on the opposite (left) side. Apparently, that was enough force from the chain, maybe my foot or something to knock the FD just a little bit out of alignment. If there's a spacer/rubber collar between the FD mounting ring and seat tube, it doesn't take an extreme amount of force to rotate the FD.

    As for routing and self-correcting. When you pedal forward, the derailleurs will simply shift the chain into the right gears. Rotating the cranks backwards (once shifted) will highlight any routing errors, kinks, excess dirt, etc in the drivetrain. It should make vey little noise with a smooth chain.
    I will check it closely. I'm kind of freaked out because the darn bike is shifting so smoothly now lol, I am afraid if I adjust it I will thow the whole drive-train out of whack. But I will see if I can just move it a little.

  9. #9
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    Quote Originally Posted by Varaxis View Post
    Are you sure it's the FD?

    Make sure the chain wraps around the pulleys properly in the back. Some novices accidentally route the chain incorrectly around the rear derailleur pulley, running on the outside of the tab.

    Without pics, vids, or seeing it in person, all I can do is guess.
    that is really funny, I did run it on the outside of teh tab, but I got the chain off and routed it correctly. There is still a problem with the chain making too much contact with the FD. Thanks for posting, and way to be spot on about a novice bike fixer.. Once I do it once, I'll never forget though, so I am learning.

  10. #10
    skilldest©
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    What happens if your turn it over an peddle it frontwards then backwards? Go to the noise. Just my thoughts! Probably not much help...

  11. #11
    Trail Ninja
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    There's a "barrel adjuster" on the front shifter, where the cable housing enters the shifter. While riding, maybe on the road in front of your house, shift into the middle ring and turn the barrel adjuster while pedaling forward and listen carefully for chain rub. Turn it one way other the other, until you get less chain rub. Stay in the middle ring and shift to various cogs in the back, and try to fine tune it to the point that there's no rub while using most of the gears in the back. Once you are satisfied with the tuning, test to see if you can shift into the other gears up front.

    Don't expect to get rid of all the rubbing, while shifting into all gears smoothly, but it should be a vast improvement. Might have to compromise with smooth shifting and noise in rub in some gears. High end bikes typically

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