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  1. #1
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    Rear derailleur folded

    Hello there, my rear derailleur folded up. Can someone give me an advice on how to fix it? I'm new to the bike scene And did search but didn't find much on how to fix it. It is a used diamondback mountai bike. Thank you

  2. #2
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    Define "folded up". If it means bent, you're looking at likely replacement (or at least the derailleur hanger). If it means the cable came undone then look at Park's setup guide.

    Rear Derailleur Adjustment | Park Tool

  3. #3
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    Subscribed, waiting for good clear pic of derailleur.

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  4. #4
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    Thank you I'm hoping it just cable came undone I'll read the guide you provided.
    Last edited by Fngride; 05-18-2017 at 11:12 AM. Reason: Info

  5. #5
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    Hello guys this is the pic of the rear derailleur it is upside down.

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  6. #6
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    Do you have the gears adjusted to the smallest chainring in the front and the smallest sprocket in the rear? That's what it looks like, which isn't the best gear to try to run in. If you switch to a/the bigger chainring in the front or bigger cassette sprockets in the rear, does that make it less "folded"?

    Depending on the gear combination you are using at any particular time, the chain will have more or less tension/slack in it, which is the purpose of the spring action that the derailleur cage with the jockey wheels serves...to keep tension in the chain.
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  7. #7
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    At the time I had it smallest on front and smallest on rear. Now the cable all loose. I wasn't suppose to run gear like that? I didn't know it seem to help most when I'm going uphill

  8. #8
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    Yes, the cable will have slack because you have it in the gear that requires no tension to hold it in that gear.

    Not sure what gearing you have (3 front x9 rear?), but you should be able to pedal in that gear combination. If it won't turn (like it's bound up..doesn't sound like it, though) the answer would be a b-screw adjustment.

    That is a cross-chained condition, though, and I would not use that gear (because of the cross-chaining and because of the "folded" condition you are concerned about). Before I used that gear, I would change the front chainring to the next bigger and the rear up 2 bigger sprockets which should be about the same gear difficulty-wise.

    Sounds like you need to do a little studying on gear selection and cross-chaining.
    Maybe try Sheldon Brown's website.
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  9. #9
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    The gear is 3 front and 8 rear. And u right I am able to change gear and now it unfold but still shifting a bit strange. So I should adjust the B screw to tighten this? I've been reading gear adjustment but it seen very confusing to me

  10. #10
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    Quote Originally Posted by Fngride View Post
    The gear is 3 front and 8 rear. And u right I am able to change gear and now it unfold but still shifting a bit strange. So I should adjust the B screw to tighten this? I've been reading gear adjustment but it seen very confusing to me
    take it to a bike shop and let them talk you through it. if you start turning things willy-nilly, you'll make it worse. The b-screw has nothing to do with this. The b-screw only adjusts how far the upper pulley is from the cassette cogs. It can bind up if it's too close to your cassette, but that's it.

    Many bike shops do small adjustments on the bike for free for some period of time, and if you're new (with a new bike), you should take advantage of this and learn something from it. If you don't have such an arrangement with your shop (used bike, internet purchase, etc), a derailleur adjustment is pretty cheap if you haven't made it worse already.

  11. #11
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    It is shifting funny because the cable tension is WAY off, you need to loosen the bolt holding the cable and pull it through to tighten it up, do not mind the rocket surgeon quoted below, a properly setup and adjust RD will not have that sort of cable slack, no matter what gear combo it's in. If reading through the Park page doesn't help, then I'd suggest you take it into a shop and have them do it for you and try to see if you can watch what they do. Also you could try searching YouTube for videos showing how to setup/adjust a rear derailleur.

    Quote Originally Posted by Fngride View Post
    The gear is 3 front and 8 rear. And u right I am able to change gear and now it unfold but still shifting a bit strange. So I should adjust the B screw to tighten this? I've been reading gear adjustment but it seen very confusing to me

    Quote Originally Posted by Spec44
    Yes, the cable will have slack because you have it in the gear that requires no tension to hold it in that gear.
    One day your life will flash before your eyes, will it be worth watching??

  12. #12
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    Thank you guys, after reading the guide i tried adjusting (messing with) the L H and B, i got it pretty smooth but still something is wrong when the chain is moving. So I took it to bike shop. As it turned out the screw that push ag ainst the derailleur hanger is not sitting on the hanger properly. I will also check the cable slack again when i get home.

    Thank all!

  13. #13
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    Quote Originally Posted by LyNx View Post
    It is shifting funny because the cable tension is WAY off, you need to loosen the bolt holding the cable and pull it through to tighten it up, do not mind the rocket surgeon quoted below, a properly setup and adjust RD will not have that sort of cable slack, no matter what gear combo it's in. If reading through the Park page doesn't help, then I'd suggest you take it into a shop and have them do it for you and try to see if you can watch what they do. Also you could try searching YouTube for videos showing how to setup/adjust a rear derailleur.
    Rocket surgeon, huh? How about engineer for 25 years? What is it you do?

    Why don't you point out what is wrong with that statement you quoted? I didn't say how much slack. When you're installing new derailleur cables every day, are you pre-tensioning that cable before you tighten the set screw? Hmm? How much?
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  14. #14
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    So is this too much slack? Is it true that it doesn't matter what combo of gear it's in it shouldn't has any slack?

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    The cable should have tension in it in that gear. The point I was making is that, when you are installing a new cable (or resetting the cable tension), the typical method is to first shift to the smallest cog, turn the barrel adjusters both in all the way, then out 1/4 or 1/2 turn, then pull the cable just snug/taught, and secure the set screw. If you need to, when adjusting the shift points, you turn the barrel adjusters which add small amounts of tension for each turn of the barrel.

    The limit screw keeps the chain on the smallest cog, not cable tension. After you make adjustments to the barrel adjusters when fine tuning the derailleur shifting, there may be some or no tension when in the smallest cog, but when you shift up the cogs from there it's the cable tension that moves the derailleur to each gear and holds it there, so there should always be tension when in any cog other than the smallest. In other words, the shifter on your handlebar, when you depress it to move up a cog is adding tension to the cable, and when it clicks is locking that tension at that point, meanwhile, the springs in the derailleur are continuously pulling against that tension to hold the derailleur in the left/right position of that cog and also keeping tension in the chain.

    What you're showing in the picture isn't necessarily "slack". Slack to me would be untensioned cable (you can easily manipulate with a finger). There will always be "exposed" cable between the cable stop and the set screw, but you need to start the whole process of attaching the cable as described above.
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  16. #16
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    If you are shifted into the smallest cog cog/last shift of the shifter, the cable "might" have a very litle bit of slack, but most definitely not what your photo shows, that means the cable is too slack and will not shift to the nest gear until you've probably shifted 2 more times.
    Quote Originally Posted by Fngride View Post
    So is this too much slack? Is it true that it doesn't matter what combo of gear it's in it shouldn't has any slack?

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    Rocket Surgeon/Engineer, Tomaeto/tomato You looked at HIS PHOTO, where the cable was clearly way slack and made the comment, implying that that was OK and it most definitely is not, but hey, I'm no engineer right, I just taught myself how to maintain and service my bikes and for lots of other people for the last 10+ years without complaints, so I must not know what I'm talking about :rolletyes:

    Quote Originally Posted by Spec44 View Post
    Rocket surgeon, huh? How about engineer for 25 years? What is it you do?

    Why don't you point out what is wrong with that statement you quoted? I didn't say how much slack. When you're installing new derailleur cables every day, are you pre-tensioning that cable before you tighten the set screw? Hmm? How much?
    One day your life will flash before your eyes, will it be worth watching??

  17. #17
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    Quote Originally Posted by LyNx View Post
    If you are shifted into the smallest cog cog/last shift of the shifter, the cable "might" have a very litle bit of slack, but most definitely not what your photo shows, that means the cable is too slack and will not shift to the nest gear until you've probably shifted 2 more times.


    Rocket Surgeon/Engineer, Tomaeto/tomato You looked at HIS PHOTO, where the cable was clearly way slack and made the comment, implying that that was OK and it most definitely is not, but hey, I'm no engineer right, I just taught myself how to maintain and service my bikes and for lots of other people for the last 10+ years without complaints, so I must not know what I'm talking about :rolletyes:
    Last post on this. I didn't say anything about whether you know what you're talking about. I don't like being called names, and certainly when they imply that I'm stupid. Maybe you shouldn't call people names.
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