# Help~ Rear Derailleur killing my frame!



## amegazero (May 4, 2009)

Hello, my fellow experts in the matter, another super noob questions for yall all, So I was practicing my bunnyhops but what REALLY bugs me is that my rear derailler (Shimano Deore) keeps hitting my frame on my land. (Or simply if I just bounce my bike it hits it too). Happens the same way with me and my friends giant yukons. 

First thing that comes to my mind was to tighten the derailler, does it make sense? Would tightening the derailler affect the shifting of the gears? 

Or can be ghetto and and put like a rubber piece to absorb the impact when it hits? (my poor frame has already a dent in it from the derailleur, 

Please enlighten me =)


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## Yukon-RSX (Feb 6, 2007)

You can wrap an inner tube round your chain stay, or cable tie a fat block of rubber onto the stay where the derailleur hits.


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## highdelll (Oct 3, 2008)

I'm not sure what you mean by 'tightening the derailleur'... do you mean screwing in the 'B-screw'? That _may_ help a smidge - not much tho.
It sounds like you may have a bit too much slack in your chain - what gear combo are you in when this happens? small-small is never a good idea.
You can wrap your stay w/ an old tube or some bar-tape or similar. 
You could also try to fashion a ghetto rubber wrap on the mech itself (comes stock on many derailleurs anyways) - Just be careful not to impede the movement of any 'hinges'.

BTW - what brand is it? I can only speak to Shimano derailleurs - I know that SRAMs 'movement' is different.


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## Yukon-RSX (Feb 6, 2007)

Even if the chain is tight I still find that my Deore derailleur clangs most of the time.


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## amegazero (May 4, 2009)

So is that how you all stop the rear derailluer from hitting the frame? mine goes up and hits it really hard, so you would not suggust tightening it? see the yukon 09 pic for reference. =) so just wrap a FAT RUBBER? lol

see that screw on the left top of the rear derailluer? can i just tighten that???

When i bunnyhopp, i'm using all the middle gears, and thats a shimano deore RD


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## amegazero (May 4, 2009)

see that screw on the left top of the rear derailluer? can i just tighten that???


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## Yukon-RSX (Feb 6, 2007)

Tightening that screw won't make any difference, but you can if you want. That screw, regardless of how tight it is, is a pivot point for the mech itself.


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## amegazero (May 4, 2009)

Well, I think my biggest concern would be if this constant hitting of the RD on the frame is good for the derailleur? Is the derailleur meant for this type of abuse? I am also starting to think it might be just my frame, does other bike frames have the RD so close to the frame that it hits when you do any jumping or bouncing?

How else do you all stop that from happening?!? =)


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## highdelll (Oct 3, 2008)

amegazero said:


> see that screw on the left top of the rear derailluer? can i just tighten that???


The screw that is facing us in that pic is the mounting bolt (allen head) - it should be snugged all the way up - period.
The 'B-screw' (phillips head usually) is also on the top-left, but not visible in the pic.
That screw MUST be behind the little tab on the derailleur hanger - if it's not there is no real tension on the fore-aft motion on the derailleur.(and you may not be able to screw in the derailleur mounting bolt properly if it isn't)
The 'B-screw' is primarily used to adjust clearance between the cogs and the top jockey wheel - but it can also have a slight effect on the overall position of the mech and thus effect how far forward the mech can swing with increasing spring tension.

gosh...I hope I'm making sense here


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## highdelll (Oct 3, 2008)

amegazero said:


> ...
> 
> How else do you all stop that from happening?!? =)


On mine (XT) there is no way for the mech to really hit the stay unless I'm in a slack-chain gear combo - even then,the part that would hit would be the cage near the top jockey-wheel - no way to wrap that part. Otherwise, the chain would 'wrap' up the cog and the jockey wheel would prevent any further forward movement.
You may have a stay that drops down further than my bike however.
First check and make sure the 'B-screw' is behind that tab (rotationally) as I suggested above (it is situated to the rear of the derailleur and located on the main pivot)...I have seen a few bikes where someone just screwed the derailleur on without paying attention to that spring-loaded pivot and just bending the screw or hanger - the derailleur might even shift 'OK' because of the friction or jamming of the screw sideways into the hanger, but the overall position of the derailleur would be more forward than it was supposed to be.


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## amegazero (May 4, 2009)

highdelll said:


> The screw that is facing us in that pic is the mounting bolt (allen head) - it should be snugged all the way up - period.
> The 'B-screw' (phillips head usually) is also on the top-left, but not visible in the pic.
> That screw MUST be behind the little tab on the derailleur hanger - if it's not there is no real tension on the fore-aft motion on the derailleur.(and you may not be able to screw in the derailleur mounting bolt properly if it isn't)
> The 'B-screw' is primarily used to adjust clearance between the cogs and the top jockey wheel - but it can also have a slight effect on the overall position of the mech and thus effect how far forward the mech can swing with increasing spring tension.
> ...


soo.........which one do i tighten? is it a good idea to stop the derailler from hitting the frame bar by making it tighter or simply rubber pad it


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## suprcivic (Aug 17, 2008)

don't tighten that screw too much or you will strip out the aluminum threads it sits in. it won't do anything for your problem.

is it the actual derailluer hitting or is it chainslap?

also, not to insult, but a lot of this could have to do with your technique. landing lightly is an art, but if you perfect it, your bike will thank you and you will spend a lot less time and money on maintaining your rig.


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## emtnate (Feb 9, 2008)

parktool.com look for the repair section. Sounds like you are not sure which one is the "B" screw and which is the mounting bolt. If you're not sure which screw does what, you shouldn't be adjusting them, you'll mess up your shifting. (not beyond repair though) 

Read up on rear dérailleur adjustments and check the slack on your chain. Like was said, if the chain is too loose, things are more likely to slap your chainstay. Are you positive it is the derailleur hitting the frame stay? It is pretty common for the top run of the chain to slap the chainstay, this is why many of us wrap a tube or tape or commercial protector around the chainstay.


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## emtnate (Feb 9, 2008)

...


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## amegazero (May 4, 2009)

Ye ait is the actual derailuer which is why its weird, i looked up on google for the chainstay and i don't think its the chaistay. I DO HOWEVER think its my technique lol, but still it should not be so "movable" that the derailler is swaying up and down with every boucing motion. "from teh picture, the top right side of the derailler hits the bottom of the bike frame

sorry for my noob bike lingo, hehe =) but yea i guess its the chainstay but only the back part that is right on top of the derailer that it is hitting


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## emtnate (Feb 9, 2008)

If it is not hitting the chainstay, then what is it hitting?


edit: the chainstay is the piece of the frame connecting the bottom bracket (where the cranks are) to the dropouts (where the rear wheel and derailleur is).

You're right, it shouldn't be so loose that things are banging around, however if you don't know the parts of the frame, you are probably in over your head with fixing it. Read the cleaning and maintenance sticky at the top of this forum and read up on bike repair at parktool.com There are some other great resources on the web as well.

Bike repair is not hard if you have basic mechanical skills. I enjoy wrenching my bike, not as much as riding, but it's still fun. I'm no expert as it takes me twice as long to fix things as it does the shop. I save money and fully understand my bike. Win / win if you ask me.


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## Yukon-RSX (Feb 6, 2007)

To make it clear. This is what's happening...


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## highdelll (Oct 3, 2008)

amegazero said:


> soo.........which one do i tighten? is it a good idea to stop the derailler from hitting the frame bar by making it tighter or simply rubber pad it


dood, not to be mean but, are you reading my posts?
The big bolt/ screw necessarily needs to be tightened all the way - if it's already tight (ie. not easily turned) do not go any further - as you will strip the threads - think of it as a normal bolt - tight=tight (roughly - people, don't get on me w/ semantics)
there is another screw... 'B'-screw that... aww fcuk it - re-read my posts 

***EDIT*** to be clear...the big bolt (usually shiny chrome hex/allen) DOES NOT restrict movement on the derailleur!!! It simply mounts it to the hanger or frame. If it IS loose, that certainly is a problem - but because the body of the derailleur moves does not mean that it is not tight enough... It is SUPPOSED to pivot there!! :thumbsup:


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## amegazero (May 4, 2009)

sorry for my noob bike lingo, hehe =) but yea i guess its the chainstay but only the back part that is right on top of the derailer that it is hitting


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## amegazero (May 4, 2009)

I was looking up the issue with a bunch of different forums and it appears that it happens a lot to low-end beginner bikes, and some even suggests that it was my chain that was too long. 

Does any of you know how to check for chain length? THANKS!


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## Ken in KC (Jan 12, 2004)

*You're killing me, Smalls...*



amegazero said:


> sorry for my noob bike lingo, hehe =) but yea i guess its the chainstay but only the back part that is right on top of the derailer that it is hitting


You have a couple options:

1. Add a chain stay protector. This is what most experienced riders do. Whether it's a specific, purchased chainstay protector (Lizard Skin) or a tube wrapped and ziptied to your chainstay, this is what most of us do to prevent chain slap from damaging our bikes. Chain slap is the chain slapping the chainstay.

2. Take your bike in to a local shop and ask them for help in ensuring that your rear derailer is adjusted properly. There are basically 3 screws that you can adjust on a rear derailer (as others have already mentioned): The mounting screw. It's an allen head that should be tight. The two adjustment screws are phillips heads and they're used to adjust the upper and lower adjustment limits of the derailer. No amount of adjusting these will stop the derailer from moving up and down along the same plane as your chainstay.

3. If your rear derailer is adjusted properly and it still slapping your chainstay, consider a newer, better rear DR.


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## highdelll (Oct 3, 2008)

amegazero said:


> I was looking up the issue with a bunch of different forums and it appears that it happens a lot to low-end beginner bikes, and some even suggests that it was my chain that was too long.
> 
> Does any of you know how to check for chain length? THANKS!


To check for proper chain-length, FIRST!!, make sure you have a good chain-breaker, and more importantly, be able to use it ( ie. pinning the chain back together).

If you know how to use it, OR have a 'master-link' of some sort (you should still master breaking/ joining chains regardless), Pull the chain all the way out of you drive-train.
THEN, (without routing through the derailleur), wrap the chain around your biggest cog in the rear (cassette) and the biggest chain-ring in the front (crankset) and pull the ends taut.
The formula simplified is 'big-big+2' - the 2=two links (always 'cheat' on the loose side- better to have loose chain than broken mech)...if you you are using a 'quick-link' or similar, add another, but make sure the links that remain to be joined will fit. Pinned=male (inner-plate) to female (outer-plate) OR of having a 'quick' link, make sure you leave it 'male' to 'male'. <~~~ man that's gay  J/K
I'm an elementary humorist sometimes


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## EJ_92606 (Jul 11, 2004)

The video shows it well...shimano derailleurs bang against horst link pivot bikes. I just put a shimano shadow on and it no longer bangs...you still have a little chain slap though. SRAM will give the same benefit.


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## amegazero (May 4, 2009)

ahahahahah u crack me up buddy! will do, what would you all recommend a nice chain removing tool, i was looking at the Park tool http://www.rei.com/product/760717

Would that be good enough to take off my KMC Z72 chain?


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## highdelll (Oct 3, 2008)

amegazero said:


> ahahahahah u crack me up buddy! will do, what would you all recommend a nice chain removing tool, i was looking at the Park tool http://www.rei.com/product/760717
> 
> Would that be good enough to take off my KMC Z72 chain?


Nah man, the way they try to make you break the chain is weak!!
I first, recommend a real breaker for home use, and for trail-side repairs a multi-tool like the CB-17 (crank bros.) The nice thing about the CB-17, is that it's set to stop right before it pushes the pin all of the way out - very handy while being on the trail - plus the whole tool is unsurpassed IMO for everything else IMO...I'll try to find links to what 'I' think is good.


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## highdelll (Oct 3, 2008)

home chain-breaker comparable to park tool (park is better IMO in many cases, but I'm givin a cheaper/*quality* link) - HERE ( in this case, 'cheaper' does not equal crap - it equals inexpensive - Sette is USUALLY awesome)

Trail - nuthin beats CB-17 IMO
there is a 'cheaper' version available there - it's just NOS and missing anodized and grippy side rails - link...


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## amegazero (May 4, 2009)

thanks guy, also a chain breaker also puts it back together right? it doesn't just "break it" right???


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## emtnate (Feb 9, 2008)

You can replace the pins with the chain breaker, provided you

1. don't have a shimano brand chain
2. don't push the pin out all of the way

just flip the chain around in the tool and use it to push the pin back in.

Your best option will be to get a master link. Then you can take the chain on and off without breaking it each time.

I own the park multi-tool you linked to. It isn't bad. There's a tire lever that has a hex shaped hole that fits in the bolt of the chain tool acting as a nice handle. It isn't perfect, but works for trailside repairs.

I use a different tool at home.


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## pauldaft (Aug 10, 2009)

I have the same problem of the rear derailleur (top jockey wheel cage) hitting the frame just forward of the pivot point when in the smallest cog. it only happens when i'm going pretty fast over big bumps but it is annoying.

My bike is new so i don't think the chain length is the issue. it's a Kona cinder cone btw.

the only way i've found to stop it is to ride in a higher gear on the back. this moves the derailleur out of the way of the frame.


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## Dremer03 (Jun 19, 2009)

Are you positive that it is the actual derailluer hitting? More than likely it is the chain hitting, and there is no way to prevent it. You can buy one of these to keep the annoying sounds down and help prevent damage.

http://www.pricepoint.com/detail/15...ection/Sette-Neoprene-Chainstay-Protector.htm

http://www.pricepoint.com/detail/14...ection/Lizard-Skins-Chainstay-Super-Jumbo.htm

http://www.pricepoint.com/detail/15...tte-Kevlar-_-Neoprene-Chainstay-Protector.htm

If it is a aluminum frame you will need a large or jumbo protector. You can also cut up and attach a old tube or tire with zip ties, but using a protector is a cleaner look.


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## boomn (Jul 6, 2007)

Vtolds said:


> Are you positive that it is the actual derailluer hitting? More than likely it is the chain hitting, and there is no way to prevent it. .


My wife's bike came with a Deore derailleur and did this very same thing. It was definitely the derailleur body hitting the frame, which I easily verified based on the large chip in the paint in the exact spot where the body would hit. It did this starting with the very first ride and was "loose" from the day I bought it

The root cause of this problem appears to be a very weak spring in the main pivot (derailleur hanger bolt) of the Deore derailleur and no physical stop to prevent it from rotating that far. I could push the body up into contact with the frame with surprisingly little effort (almost none), so it is no surprise that it was smacking the frame after every bump. I installed an SLX Shadow on her bike and it solved the problem. That main spring is stiffer and there is also a physical stop built in so it can't possibly hit the chainstay


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## pauldaft (Aug 10, 2009)

Boom, this seems to be exactly what's happening to me, big chip in the paint where the point of contact is (it's so close to the wheel spindle that there's no way to put protection there). Mine has shimano LX on the rear. I will just have to live with it i suppose, unless there are any other suggestions? is there any adjustment on the spring tension on these derailleurs?


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## JonathanGennick (Sep 15, 2006)

Some of the newer Shimano derailers have stronger spring tension than their older models. Look for one of the "Shadow" models, like the SLX Shadow. You could also switch to SRAM, but then you'd need new shifters as well, and that gets into real money.


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