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Is my rear derailleur in the wrong position?

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Is my rear derailleur in the wrong position?

Old 10-12-15, 02:21 AM
  #1  
gatto karma
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Is my rear derailleur in the wrong position?

HI,

I am fixing this bike and I was a bit puzzled by how the rear derailleur was set up. Please see picture.

Shouldn't the left part of the dereilleur (where it opens into a 'C' - sorry but I don't know how to call it in English) be aligned with the frame's rear dropouts, meaning it should also 'contain' the wheel's axle?

I have tuned the derailleur and it works fine, except the screw that limits the low gear is broken so if the cable is pulled too much it falls between the freewheel and the spokes.

Summing up:

1. Is it OK if RD sits like that?
2. Does anyone know how to get around the low gear limit screw being broken? I do not seem to be able to take it out withough breaking some of the plastics

Thanks!

Attached Images
File Type: jpg
rear derailleur.jpg (90.0 KB, 177 views)

Last edited by gatto karma; 10-12-15 at 02:26 AM.
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Old 10-12-15, 03:12 AM
  #2  
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The RD isn't meant to sit like that. The axle should go through the slot in the hanger.

The screw that is holding it in at the moment is only meant to hold the RD in position when the wheel is out. I'd worry about it being strong enough for the repeated strain from shifting even if everything is working at the moment.

How is the limit screw broken? Messed up tool slot? Stripped? All I've ever seen have been possible to simply back right out.
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Old 10-12-15, 04:00 AM
  #3  
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Thanks a lot! I suspected so.

it looks like the thread within the RD has been broken so the screw would not screw/unscrew.. if I pull it, it comes out in a tilted way (like tiliting left and right) but would not unscrew completely...

if you look the picture closely you would see that the two limit screws are not parallel two each others? one comes out in a kind of tilted way

maybe i will post a better picture with a closeup to the screws today/tomorrow

Last edited by gatto karma; 10-12-15 at 04:12 AM.
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Old 10-12-15, 05:37 AM
  #4  
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Originally Posted by gatto karma View Post

Shouldn't the left part of the dereilleur (where it opens into a 'C' - sorry but I don't know how to call it in English) be aligned with the frame's rear dropouts, meaning it should also 'contain' the wheel's axle?

I have tuned the derailleur and it works fine, except the screw that limits the low gear is broken so if the cable is pulled too much it falls between the freewheel and the spokes.

Summing up:

1. Is it OK if RD sits like that?
2. Does anyone know how to get around the low gear limit screw being broken? I do not seem to be able to take it out withough breaking some of the plastics

Thanks!
That's called a "Claw", and yes, as dabac says, it should be under the axle nut, with the small screw, and a semi-circle nut should be in the slot to hold the derailleur in place when the wheel is off. You can probably get a spare nut from a bike shop.

Maybe you can carefully bend the low limit screw back to straight, so it screws in ?? Surprised you can't remove it without causing damage.

You could replace the derailleur, but need to make sure it's a compatible model for the indexing to work properly
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Last edited by Homebrew01; 10-12-15 at 06:00 AM.
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Old 10-12-15, 05:41 AM
  #5  
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I would suggest a new derailleur (they are not terribly expensive and the derailleur going into the spokes is serious) mounted properly as in the pic below. You may need a new mounting bolt assembly, unless the inner part of yours is still present. Below is a pic of a properly mounted "claw" adapter (comes attached to the derailleur) as well as a derailleur properly mounted and the mounting bolt. Note that it's possible the derailleur is bent inward (last photo).
Attached Images
File Type: gif
claw adapter.gif (8.1 KB, 187 views)
File Type: jpg
Claw derailleur.jpg (97.1 KB, 27 views)
File Type: jpg
claw mechanism.jpg (19.3 KB, 19 views)
File Type: png
bent hanger.png (56.8 KB, 27 views)
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There's no such thing as a routine repair.

Don't tell me what "should" be - either it is, it isn't, or do something about it.

If you think I'm being blunt take it as a compliment - if I thought you were too weak to handle the truth or a strong opinion I would not bother.

Please respect others by taking the time to post clearly so we can answer quickly. All lowercase and multiple typos makes for a hard read. Thanks!

Last edited by cny-bikeman; 10-12-15 at 05:47 AM.
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Old 10-12-15, 06:30 AM
  #6  
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If you cannot adequately adjust the low limit screw then the derailleur is a goner IMO. As mentioned above replacements can be had cheaply and having the derailleur go into the spokes is a major problem/expense.
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Old 10-12-15, 07:31 AM
  #7  
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It's a fairly common mistake to try to anchor the claw using the mudguard mounting hole. The anchor for the claw should be in the dropout slot itself, thus:



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Old 10-12-15, 11:55 AM
  #8  
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I've seen this before; always worth a chuckle.

gatto karma thanks for including a photo; probably saved about 7 pages of guesswork...
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Old 10-13-15, 01:45 AM
  #9  
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Originally Posted by rmfnla View Post
I've seen this before; always worth a chuckle.

gatto karma thanks for including a photo; probably saved about 7 pages of guesswork...
haha thank you people for all the replies. i also would like to point out that the bike came like that - just to safeguard my reputation as a beginner mechanic
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Old 10-13-15, 06:29 AM
  #10  
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@gatto karma, you may or may not need a new derailleur. Consider this one to be a learning tool. If you take precautions, you can avoid any damage to the wheel from an improperly adjusted or bent derailleur.

Once you correct the installation problem, try to straighten the bent screw gently with pliers so that it can unscrew without striking the derailleur body. Judging from the photo, the screw was probably bent because the bike was dropped on its side.

Install the chain and use the last photo in Post #5 to check if the derailleur is bent. If so, determine whether it's the hanger, the derailleur, or both that need straightening. They should be straightened while off the bike to avoid bending the dropout. Reinstall them and check again for alignment.

The next step is important since you don't have a spoke protector. With the shift lever in the lowest position and the chain manually placed on the largest cog and smallest chain ring, check that the derailleur (viewed from the rear) is aligned with the cog and not trying to push the chain to the left. Adjust the lower limit screw accordingly.

If everything is good so far, try rotating the pedals and shifting through the gears. With the chain on the largest chain ring and smallest cog, adjust the upper-limit screw if the derailleur is trying to move the chain to the right of the cog.

If the cable is properly adjusted and shifting is normal, you don't need a new derailleur.

Last edited by habilis; 10-13-15 at 07:19 AM.
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Old 10-13-15, 10:41 AM
  #11  
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Just get this, and follow the instructions:
http://www.amazon.com/Shimano-Tourne...ear+derailleur
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Old 10-15-15, 01:18 AM
  #12  
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Originally Posted by habilis View Post
Judging from the photo, the screw was probably bent because the bike was dropped on its side.
...
If the cable is properly adjusted and shifting is normal, you don't need a new derailleur.
That was correct! The screw was indeed not only bent but the phillips head had been destroyed and would not turn with a screwdriver. I took off the plastic covers and with pliers i managed to take it out and replace it with a new one.

And yes, I did not need a new RD. Generally, I follow a principle of "conservation of bike parts", for both financial and environmental reasons..so thanks to those who suggested to get a new RD, but so far this one looks OK (I have not yet test-ridden the bike, but turning it upside down and testing the gears everything looked OK).

Would you guys mind doing a quality check to see if the RD has been re-installed properly? Any comment/suggestion is welcome. The onyl problem I see is that, installed so, the RD will come out each time I take out the back wheel, not ideal. I wasnt able to get th esemi-circle nut that should hold the derailleur in place when the wheel is off into the hole in the frame.

I attach pics from the side (chain in low and high position) and from the back (chain in low position - the RD low limit is conservatively aligned a bit on the inside to avoid the RD to catch the spokes... there are no many hills around here so I practically never use the biggest cog anyway).
Attached Images
File Type: jpg
RDlowside.jpg (98.0 KB, 31 views)
File Type: jpg
RD2highside.jpg (97.5 KB, 29 views)
File Type: jpg
RDlowback.jpg (95.0 KB, 26 views)

Last edited by gatto karma; 10-15-15 at 02:07 AM.
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Old 10-15-15, 02:20 AM
  #13  
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Originally Posted by gatto karma View Post
Would you guys mind doing a quality check to see if the RD has been re-installed properly?
Looks fine to me.

POSSIBLY, both wheel and derailer is a bit far back, as the d-shaped nut/washer would originally have sat behind the axle in the dropout.
But as long as brakes line up OK and there's no issue with fender clearance etc it should work just fine.

Having the derailer flop around when the wheel is out should be a manageable issue. How often do you plan to remove your wheel anyway?

You might pop in at any bike shop you pass, maybe they'll have, and let you scrounge a d-nut/washer from a parts bin or a discarded derailer.
Depending on the amount of clearance to the smallest sprocket, you might be able to use a longer screw, a washer and a regular nut instead.
Or drill and tap a corresponding hole in the dropout for where the derailer sits now.
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Old 10-15-15, 03:11 AM
  #14  
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Originally Posted by dabac View Post
Looks fine to me.

POSSIBLY, both wheel and derailer is a bit far back, as the d-shaped nut/washer would originally have sat behind the axle in the dropout.
dabac, do you mean a screw should go through the hole next to the claw, the frame's droputs (it could not possibly pass through anywhere else, excpet i drill a hole) with the D-shaped washer on the other side of teh frame so the screw screws on it?

I do still have the D-shaped washer.. just didnt know what to do with it
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Old 10-15-15, 05:57 AM
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Originally Posted by gatto karma View Post
dabac, do you mean a screw should go through the hole next to the claw, the frame's droputs (it could not possibly pass through anywhere else, excpet i drill a hole) with the D-shaped washer on the other side of teh frame so the screw screws on it?

I do still have the D-shaped washer.. just didnt know what to do with it
Look at the pics posted by JohnDThompson earlier. The D-shaped washer will be a nice fit in the axle slot in the dropout.
Remove wheel, install derailer with D-washer riding in axle slot. Tighten screw. Install wheel. Axle will sit maybe 1/2" further ahead, so you need to align manually. Done.
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Old 10-15-15, 06:00 AM
  #16  
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Ok! NOW I got it!
Sorry for being a bit dense!
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Old 10-15-15, 06:13 AM
  #17  
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Look at the pics previously provided in post 5 and 7 above. They show how to mount the derailleur properly, using the bolt and d-shaped nut. You remove the wheel completely, mount the derailleur with the bolt/nut IN the dropout, then mount the wheel, being careful to center the wheel. That way the derailleur is in the best position for shifting and will not fall off when mounted. The hole in the frame is for fenders or a rack.
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There's no such thing as a routine repair.

Don't tell me what "should" be - either it is, it isn't, or do something about it.

If you think I'm being blunt take it as a compliment - if I thought you were too weak to handle the truth or a strong opinion I would not bother.

Please respect others by taking the time to post clearly so we can answer quickly. All lowercase and multiple typos makes for a hard read. Thanks!
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