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Rear derailleur confusion here

Old 09-20-23, 07:29 PM
  #26  
oldbobcat
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https://www.parktool.com/en-us/blog/...eur-adjustment
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Old 09-20-23, 07:43 PM
  #27  
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And it looks like the wheel is not all the way up in the drop out if you see the outline above where the QR attaches.
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Old 09-20-23, 08:20 PM
  #28  
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Each limit screw touches part of the derailleur body to prevent it from moving farther. In your photo, with the chain on the biggest cog , one of the two screw's points will be touching or close to the corresponding spot on the derailleur body, while the other one has a big gap. Shifted to the smallest cog (the High limit), now that other screw will be close or touching, and the one for the biggest cog (the Low limit) will have a big gap.

The advice to follow the Park Tool Repair Guide is really helpful -- I like that it starts from scratch, with essentially no prior knowledge needed, and works through the derailleur alignments step by step.
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Old 09-20-23, 08:26 PM
  #29  
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Originally Posted by Kontact
And the cable is routed wrong. It goes to the outside of the bolt, and that's the explanation.
Do these older derailleurs have a groove in the clamp faces that the bolt holds together? The cable fits into the groove. That's a good clue on newer derailleurs.

Which side the cable goes at the clamping bolt is critical!
Years ago, I unknowingly clamped my Campagnolo 10 speed derailleur cable on the wrong side of the bolt. That difference in cable angle was enough to throw off the shifting. I could get either the top half or bottom half of the cog to shift cleanly, while the other half was very noisy. It took me a lot of wasted troubleshooting to figure it out -- after I noticed the correct clamping on a new bike at the bike store.
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Old 09-20-23, 08:26 PM
  #30  
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Is it just me or does that dropout look bent open?
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Old 09-20-23, 09:20 PM
  #31  
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Originally Posted by dedhed
Is it just me or does that dropout look bent open?
think it might be the lack of hanger?

Also the fact both the high limit & low limit screws are at the extreme outboard end of their travel suggests to me the mount point is bent inwards or maybe it’s a symptom of the wheel not being fully in the dropout on that side.
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Old 09-20-23, 09:23 PM
  #32  
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Originally Posted by rm -rf
Do these older derailleurs have a groove in the clamp faces that the bolt holds together? The cable fits into the groove. That's a good clue on newer derailleurs.

Which side the cable goes at the clamping bolt is critical!
Years ago, I unknowingly clamped my Campagnolo 10 speed derailleur cable on the wrong side of the bolt. That difference in cable angle was enough to throw off the shifting. I could get either the top half or bottom half of the cog to shift cleanly, while the other half was very noisy. It took me a lot of wasted troubleshooting to figure it out -- after I noticed the correct clamping on a new bike at the bike store.
Worked on a mate’s Allez recently where he’d upgraded the group to Tiagra 4700 and got the FD cable clamped the wrong side of that little pin. Made the front shifting horrible. Such a tiny mistake.
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Old 09-21-23, 02:33 AM
  #33  
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Originally Posted by grumpus
Move the derailleur in and out while looking at the threaded ends of the adjusting screws - the one that gets closer to the stop tab when you push the derailleur in is the low limit screw.

The floor is in focus, the derailleur isn't. Probably not easy to see on a small screen.Focus is fine in that one, but the cable clamp looks incorrectly positioned.
except the Cable is EXACTLY where it Should Be in the pic... I have an STX RD sitting here on the desk, and a few more in the bin, plus three on bikes here....The Cable is Routed Correctly.

the Cable Housing is a couple inches too short, though.... meh, it'll work for now..

Last edited by maddog34; 09-21-23 at 02:37 AM.
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Old 09-21-23, 05:15 AM
  #34  
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Originally Posted by choddo
think it might be the lack of hanger?
Of course it’s got a hanger. What do you think the derailleur is attached to?

It doesn’t have a “replaceable” hanger.

Last edited by smd4; 09-21-23 at 05:27 AM.
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Old 09-21-23, 05:29 AM
  #35  
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Originally Posted by smd4
Of course it’s got a hanger. What do you think the derailleur is attached to?

It doesn’t have a “replaceable” hanger.
Given I am a lifelong pedant, I have to concede that one.
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Old 09-21-23, 05:58 AM
  #36  
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Originally Posted by dedhed
Is it just me or does that dropout look bent open?
Bingo. The missing paint seems to confirm this.
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Old 09-21-23, 06:27 AM
  #37  
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Maybe there's enough wrong with the bike to justify buying a new one!

And this time...try to take care of it.
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Old 09-21-23, 07:16 AM
  #38  
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Originally Posted by maddog34
except the Cable is EXACTLY where it Should Be in the pic... I have an STX RD sitting here on the desk, and a few more in the bin, plus three on bikes here....The Cable is Routed Correctly.

the Cable Housing is a couple inches too short, though.... meh, it'll work for now..
The cable shouldn't be routed through the bent tab. That tab is to prevent the plate from turning, and should be rotated out of the cable path.
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Old 09-21-23, 08:20 AM
  #39  
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Originally Posted by Kontact
The cable shouldn't be routed through the bent tab. That tab is to prevent the plate from turning, and should be rotated out of the cable path.
I think the cable is routed correctly. Here are a few pictures of an STX on my Trek 750.





There really isn't another cable-and-clamp configuration that makes sense here.

For what it's worth, I have this shifting a 7-speed cassette with a Suntour 8-speed indexed thumb shifter and it shifts well.
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Old 09-21-23, 09:52 AM
  #40  
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Originally Posted by juntjoo
The axle slots on the vertical dropout are supposed to be parallel, those are not.Bent dropout.

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Old 09-21-23, 10:41 AM
  #41  
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I wouldn't claim the drop out as bent until seeing it with the wheel out. vertical drops usually are intended for the axle to be fully inserted in them. This axles does not appear to be fully inserted as noted by some others. So possibly it's hiding the edge that is parallel to the other.

The cassette is a CS-HG30-81. Which I think is a 32T on the biggest cog. I wonder if the OP swapped cassettes and is outside the specs and tried to make it work by not putting the wheel all the way in the drop? Haven't looked up the specs for that RD. Just wildly guessing though as we all do sometimes. Maybe it'll make the OP give additional info though.
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Old 09-21-23, 10:45 AM
  #42  
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Originally Posted by hokiefyd
I think the cable is routed correctly. Here are a few pictures of an STX on my Trek 750.





There really isn't another cable-and-clamp configuration that makes sense here.

For what it's worth, I have this shifting a 7-speed cassette with a Suntour 8-speed indexed thumb shifter and it shifts well.
You make me so ashamed of my filthy bike! But even after I clean it, I'll still be ashamed. I know I won't have the wherewithal to clean it often enough. Or is that why you probably have several dozen bikes? So the dirty one can be hid! <grin>
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Old 09-21-23, 11:47 AM
  #43  
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Originally Posted by Iride01
You make me so ashamed of my filthy bike! But even after I clean it, I'll still be ashamed. I know I won't have the wherewithal to clean it often enough. Or is that why you probably have several dozen bikes? So the dirty one can be hid! <grin>
That cassette is almost criminally clean.
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Old 09-21-23, 12:07 PM
  #44  
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Originally Posted by smd4
Cable puller is complete and unnecessary overkill. Pliers are fine; needle nose probably the easiest.
I usually just put it in a low gear, click up several gears without pedaling, so the chain holds the derailleur and the cable is slack. Then you can pull the cable with nothing more than a finger and thumb. If you pull too much you can slacken the pinch bolt and let the derailleur pull it back.
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Old 09-21-23, 12:14 PM
  #45  
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Originally Posted by hokiefyd
I think the cable is routed correctly. Here are a few pictures of an STX on my Trek 750.
There really isn't another cable-and-clamp configuration that makes sense here.
Rotate the anti-rotation tab 90 degrees in either direction, whichever way it locates properly. The cable shouldn't be trapped by the tab, just held in the groove on the derailleur arm. That's just general advice, there may be exceptions (I'm thinking of some old Simplex derailleurs, I'm sure there are more).
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Old 09-21-23, 12:30 PM
  #46  
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Originally Posted by choddo
That cassette is almost criminally clean.
To be fair, this is a nearly new cassette. Microshift 12-28 7-speed jobbies were recently on a huge discount on Amazon and I bought a few.
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Old 09-21-23, 12:38 PM
  #47  
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Originally Posted by grumpus
Rotate the anti-rotation tab 90 degrees in either direction, whichever way it locates properly. The cable shouldn't be trapped by the tab, just held in the groove on the derailleur arm. That's just general advice, there may be exceptions (I'm thinking of some old Simplex derailleurs, I'm sure there are more).
The plate with the tab will not clock 90 degrees to either direction. The cable is designed to be trapped between the tab and the cinch bolt shaft. I have a picture below of the serrations on the derailleur body (inboard of the cinch bolt), the serrations on the plate, parallel with and next to the tab, and an image showing how the plate won't turn 90 degrees and still clamp on the derailleur. If you look closely, the washer plate has a non-circular center hole, which actually matches the bolt with a non-circular shaft. The plate can be rotated 180 degrees on the bolt, but not 90 degrees.

juntjoo has this cable routed correctly.




Last edited by hokiefyd; 09-21-23 at 12:53 PM.
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Old 09-21-23, 12:48 PM
  #48  
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Originally Posted by hokiefyd
The plate with the tab will not clock 90 degrees to either direction. The cable is designed to be trapped between the tab and the bolt threads. I have a picture below of the serrations on the derailleur body (inboard of the cinch bolt), the serrations on the plate, parallel with and next to the tab, and an image showing how the plate won't turn 90 degrees and still clamp on the derailleur. If you look closely, the washer plate has a non-circular center hole, which actually matches the bolt with a non-circular shaft. The plate can be rotated 180 degrees on the bolt, but not 90 degrees.

It's actually not an anti-rotation tab in this case...the shape of the bolt shaft and nut keep that plate from spinning -- not the tab itself.

juntjoo has this cable routed correctly.



Excellent post. Wonder if @Kontact will ever admit he was wrong?

Originally Posted by Kontact
And the cable is routed wrong. It goes to the outside of the bolt, and that's the explanation.
​​​​​​​

Originally Posted by Kontact
The cable shouldn't be routed through the bent tab. That tab is to prevent the plate from turning, and should be rotated out of the cable path.
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Old 09-21-23, 01:21 PM
  #49  
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Originally Posted by smd4
Excellent post. Wonder if @Kontact will ever admit he was wrong?

I have built and serviced a hundred STX equipped bikes, and Shimano never made tabs you need to remove or fish through. If this one won't locate properly, it isn't the right part or has been modified.

How often am I ever wrong about this kind of thing?





​​​​​​​See the tab? Image search is your friend.

Last edited by Kontact; 09-21-23 at 01:28 PM.
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Old 09-21-23, 01:50 PM
  #50  
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Shimano have several different styles of cinch bolts on the STX line of deraillers. I have two of them. One as pictured on the Trek 750 and one matching what is more commonly seen in an image search (my picture below). Critically, it's not correct to route the cable to the outside of the bolt, with either style.

With the style of cinch bolt and plate juntjoo has, the cable is routed correctly.

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