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HELP front derailleur problems

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HELP front derailleur problems

Old 01-26-17, 10:22 AM
  #1  
TomTcyling
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HELP front derailleur problems

Hello, first time posting on a forum but I have used this a few times to help me repair bits and pieces on my bikes.


However, I have a problem with a bike I cant get to the bottom of or find a relevant thread about. My gears (11 speed ultegra) were working okay ready for my first race of the year in a few weeks, but I noticed my front derailleur was rubbing slightly when in my hardest gear (big cog on front and lowest gear of my rear cassette) so thought I would adjust the limit screws slightly to prevent the rub and annoying noise.


When I did this, I realised my limit screws didn't seem to be moving the derailleur at all. With the chain then on the inner ring and lowest gear, I tried to adjust and still nothing. I then made a decision to play with the cable tension which proved to be a big mistake. After disconnecting it, I tried the limit screws again and seemingly nothing happened. I then decided to move the limit screws back to their original position and reconnect the cable. However, I then realised that my shifter then would then not make the derailleur move at all. I'm probably doing something stupid, but the cable is seemingly a similar tension to before I disconnected it, but using the shifter seems to be having no effect at al on the derailleur, not moving even a smidge. Anybody come across this before? and any solution other than taking it to a bike shop? As funds are not at a good place at this moment in time!


Cheers
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Old 01-26-17, 10:36 AM
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I think you were (maybe) describing the big-big combo (big ring in front to big ring in back) which is generally to be avoided and does put the greatest demand on the front derailleur with most liklihood to rub a little bit. Regarding how to fix what you may have messed up --I think someone experienced would need to look at it directly. Front der's can be finnicky and difficult to set up just right.
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Old 01-26-17, 10:54 AM
  #3  
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Remove the shift wire from your front derailleur (document how it was routed so that you can get it back right) and then follow this procedure from the beginning, without skipping any steps as if it was a new insatallation: Front Derailleur Adjustment | Park Tool


Since many steps depend upon the previous ones being done correctly, do not go ahead until you are sure the current step has been done right. Take you time and make adjustments gradually, lest you go past the sweet spot. 1/4 or 1/8 turn or less can make the difference between great shifting and so-so. Do not leave too much clearance when setting the low limit or you may run out of throw on the other end. You are fortunate in that your adjustments are probably close, but fiddling with things without a plan is a recipe for failure. You may not be able to avoid some rubbing in the extreme cross-chained gear combinations.
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Old 01-26-17, 11:25 AM
  #4  
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I'll guess that the cable fell out of a guide on the frame.

Yes a small change in the limit screw and a little more tension (There should be a fine adjuster) would have been the fix for what you described.

-SP
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Old 01-26-17, 11:32 AM
  #5  
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Try this tutorial on page 2
http://www.bikeforums.net/bicycle-me...rubbing-2.html

Watch this

And this

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Old 01-26-17, 11:43 AM
  #6  
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FIRST of all you need to understand the basics.

The Limit screws do just what the name implies. They determine the extreme limits in the FD's range of travel. They don't control the position which is controlled by the cable.

So, let's get back to the FD and get it dialed in.

First, let's reset the outer limit. (you'll need a stand, friend, or a way to hold the bike up with the wheel off the ground)

Shift to the inner ring. Now, disregard the levers and shift to the outer ring by pulling the bare wire away from the frame. Back off the outer limit until you can make the chain overshift and fall off the outside. Now bring the limit in by degrees until you cannot overshift, no matter hard you try. (later if you ever overshift, you'll bring it in another hair, but no more).

With the outer limit set, use the lever to shift to the outer and note the position. If it's not right, you'll need to adjust the cable length (tension) using the adjuster (if you have one), or by pulling it down in the pinch bolt. It's the cable that's key to getting the outer cage correctly positioned in high, so take your time and get it right. (A trick to make setting the cable in the pinch bolt easier is to jam a pencil into the FD mechanism to hold it out, while shifting to low to slacken the cable).

Finally, you'll set the inner limit, so it correctly trims the FD in low, when the cable is slack.
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Old 01-26-17, 11:55 AM
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on the 6800 FD the cable is never slack. So the procedure is slightly different. if it ever gets slack ,it would result in no trim at all. These FD require more tension than any previous FD's.
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Old 01-26-17, 03:52 PM
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I wasn't in my largest ring on my cassette and the top of the front cog, I don't ever ride like that so wouldn't be bothered by the clicking. The initial clicking was being in my full on hardest gear (as I I was descending on a large hill etc)
Thanks for all the advice, the derailleur is now moving again when I get the shifter going which is atleast an improvement on yesterday. But now it won't move into the top cog as the limit screw are off. Before I touch something I clearly don't understand that well again, ultegra 6800 FD, the screw furthest from the frame should set the outer limit correct? so if I turn that it should move it across? As at the moment I am turning it, but there is no movement.
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Old 01-26-17, 04:29 PM
  #9  
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Originally Posted by TomTcyling View Post
I wasn't in my largest ring on my cassette and the top of the front cog, I don't ever ride like that so wouldn't be bothered by the clicking. The initial clicking was being in my full on hardest gear (as I I was descending on a large hill etc)
Thanks for all the advice, the derailleur is now moving again when I get the shifter going which is atleast an improvement on yesterday. But now it won't move into the top cog as the limit screw are off. Before I touch something I clearly don't understand that well again, ultegra 6800 FD, the screw furthest from the frame should set the outer limit correct? so if I turn that it should move it across? As at the moment I am turning it, but there is no movement.
The front derailleur limit screws limit the how far the derailleur will travel, they are merely stops. Their adjustment won't cause the derailleur to move.
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Old 01-26-17, 04:45 PM
  #10  
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The ''top cog'' is better refered to as the outer chainring (or big ring).

If the chain wont shift from the inner ring onto the big ring that suggests the outer limit screw (furthest screw from the frame) is in too WAY far, and needs to be turned outwards.

On the FD look closely at the bottom of the outer limit screw, atm it will be touching a stop on the FD. Back the screw off and the FD now has more room of travel. If its touching the stop it cannot travel any further. So the chain will not move up onto the big ring.

The outer limit screw comes into play once the chain is on the big ring. Its function is to prevent the outer cage moving too far and throwing the chain off over the big ring. So its purpose is to limit the travel of the cage.

When the chain is on the big ring, look at the small gap between the chain and outer cage. It should 1mm or less without rub if you spin the crank. If the gap is bigger, the outer limit screw needs to be turned inwards in small increments, so it will move the cage inwards to the desired position.

Last edited by trailflow1; 01-26-17 at 05:21 PM.
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Old 01-26-17, 04:48 PM
  #11  
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But watching the video, turning the screws changes the alignment, im turning the screw (now with cable unattached) and there is no movement. Any ideas?
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Old 01-26-17, 05:05 PM
  #12  
trailflow1
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The inner screw changes the cage alignment but only on the inner position. Because the FD naturally rests on the inside stop when not under tension.

To adjust the inner limit screw (closest to the frame) , put the chain on the inner ring and biggest cog (easiest gear). Then turn the inner limit screw inwards and the FD cage will move outwards and vice versa. It should adjusted so the gap between the inner cage plate and chain should be 1mm or less.

Check the outer limit screw is not preventing the cage from moving. If so, turn it outwards nearly all the way before hand. If you don't do this first, the cage cannot travel anywhere.

Last edited by trailflow1; 01-28-17 at 04:16 PM.
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Old 01-26-17, 05:40 PM
  #13  
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Originally Posted by trailflow1 View Post
The inner screw changes the cage alignment but only on the inner position.

To adjust the inner limit screw (closest to the frame) , put the chain on the inner ring and biggest cog (easiest gear). Then turn the inner limit screw inwards and the FD cage will move outwards. It should adjusted so the gap between the inner cage plate and chain should be 1mm or less.

Check the outer limit screw is not preventing the cage from moving. If so, turn it outwards nearly all the way before hand. If you don't do this first, the cage cannot travel anywhere.
That's a good way to ruin a FDER.
The aluminum casting is too soft to use the STEEL limit screw as a jacking screw. It doesn't take long and you have sloppy threads.
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Old 01-26-17, 05:49 PM
  #14  
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How else would you adjust it, magic ? The limit screw is designed to touch the metal. what are you on about ?

Been cycling 25 years never had a sloppy inner limit screw thread, what am i doing wrong ?

Last edited by trailflow1; 01-26-17 at 05:58 PM.
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Old 01-26-17, 06:06 PM
  #15  
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To set the lower limit, have the chain on a larger ring and screw it in enough that the chain WON'T drop to the smallest ring.
Push the cage over a bit and back the screw out a bit.
Repeat until the shift to the smallest ring occurs reliably.
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Old 01-26-17, 06:13 PM
  #16  
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OP consistently does exactly the wrong thing and ignores excellent advice. This thread must be a troll.
[Just for reference: front chain rub would indicate first touching the FD barrel adjuster as the high limit screw would not be in play except during an up-shift -- all the rest is nonsense.]
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Old 01-26-17, 06:24 PM
  #17  
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Originally Posted by Bill Kapaun View Post
To set the lower limit, have the chain on a larger ring and screw it in enough that the chain WON'T drop to the smallest ring.
Push the cage over a bit and back the screw out a bit.
Repeat until the shift to the smallest ring occurs reliably.
or just adjust the screw that was put there for the sole purpose of adjusting the inner limit.
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Old 01-26-17, 06:52 PM
  #18  
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Originally Posted by trailflow1 View Post
or just adjust the screw that was put there for the sole purpose of adjusting the inner limit.
It is put there to limit the travel of the derailleur not to move the derailleur by working against the pressure of the derailleur spring. I agree that adjusting it under pressure may lead to damage and is best avoided.
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Old 01-26-17, 07:11 PM
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Originally Posted by Bill Kapaun View Post
That's a good way to ruin a FDER.
The aluminum casting is too soft to use the STEEL limit screw as a jacking screw. It doesn't take long and you have sloppy threads.
Originally Posted by L134 View Post
It is put there to limit the travel of the derailleur not to move the derailleur by working against the pressure of the derailleur spring. I agree that adjusting it under pressure may lead to damage and is best avoided.
Every time a shift is made between the inner/outer ring, the screw(s) rests against the stop(s) under the springs pressure, and can withstand repeated numbers (thousands) of shifts. Which suggests the screw and it's thread have a reasonable degree of strength and durabilty. The small adjustment that is needed (half a full turn) of the inner screw whilst its resting on the stop is really insignificant. It was designed to cope with much more force. By your reckoning. The screw thread would get damaged from the shifting alone. yet it does not.
Shimano doesn't say to use the method you describe.
So i think what you say is a myth sorry. But the screw is easier to turn if its not resting of the stop, i'll agree with that.

Last edited by trailflow1; 01-28-17 at 04:59 PM.
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Old 01-27-17, 02:40 PM
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I now have the front derailleur moving freely thanks, but now, as when I began, the chain is rubbing on the front derailleur when I am in my hardest gears (lowest in casette).
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Old 01-28-17, 04:14 PM
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Then either

1. There isn't enough tension on the cable to pull the cage to give the clearance needed. If you have a barrel adjuster. Turning the barrel outwards incrementally will move the derailleur cage further outwards.

2. The high limit screw is still in too much, and is preventing the cage moving outwards any further.

or a combination of both.

Also, If the outer cage edge is not perfectly parallel with the chain ring. It will cause rubbing rub on the chain. So make sure it is properly aligned.

If you have a braze-on style FD. Make sure the support bolt is touching the frame. So there is sufficiant stiffness of the FD and there isn't any unwanted flex or movement when shifting.

Last edited by trailflow1; 01-28-17 at 04:56 PM.
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Old 01-28-17, 05:20 PM
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Originally Posted by trailflow1 View Post
Every time a shift is made between the inner/outer ring, the screw(s) rests against the stop(s) under the springs pressure, and can withstand repeated numbers (thousands) of shifts. Which suggests the screw and it's thread have a reasonable degree of strength and durabilty. The small adjustment that is needed (half a full turn) of the inner screw whilst its resting on the stop is really insignificant. It was designed to cope with much more force. By your reckoning. The screw thread would get damaged from the shifting alone. yet it does not.
Shimano doesn't say to use the method you describe.
So i think what you say is a myth sorry. But the screw is easier to turn if its not resting of the stop, i'll agree with that.
The screw IS the stop.
1/2 turn? You must be quite lucky.

The steel screw is HARD compared to the aluminum. Some screws don't have as smooth of a thread as they should, which can easily "cut" into the aluminum.

Back when I first started and was ignorant about FDER adjustments, I wallowed out the threads bad enough that I had to use blue locktite to keep the screw from backing out under normal use.

Your belief that a stop screw and a jacking screw function the same is just plain flawed.
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Old 01-31-17, 08:11 AM
  #23  
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Originally Posted by trailflow1 View Post
Then either

1. There isn't enough tension on the cable to pull the cage to give the clearance needed. If you have a barrel adjuster. Turning the barrel outwards incrementally will move the derailleur cage further outwards.

2. The high limit screw is still in too much, and is preventing the cage moving outwards any further.

or a combination of both.

Also, If the outer cage edge is not perfectly parallel with the chain ring. It will cause rubbing rub on the chain. So make sure it is properly aligned.

If you have a braze-on style FD. Make sure the support bolt is touching the frame. So there is sufficiant stiffness of the FD and there isn't any unwanted flex or movement when shifting.
Hi, I still can't get it to work for some reason. The derailleur is paralell, the support bolt is touching the frame, the cable has about as much tension as I can give it. It just won't stop rubbing. I've followed steps from parktool, the alignment etc was right all the way through the steps, I just can't stop this rubbing! Any other ideas?
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Old 01-31-17, 08:50 AM
  #24  
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Could it be that the bottom bracket spindle is not the correct length for the crank and is placing the chainrings out too far?
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Old 01-31-17, 09:00 AM
  #25  
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Try EXTRA tension. Do the trick in the second video above but pull the cable even harder when clamping it. You'll be able to get a better grip of the cable if you pull it with small set of pliers with your right hand, and tighten the bolt with your left hand and hex key.

Remember if you dont first back out the high limit screw outwards far enough. No matter how much high tension the cable has, the FD cage movement will be prevented from moving if the screw is in too much. That is important. Back the screw out nearly all the way so there is no chance whatsoever of it stoping the FD from moving before attempting anything else.

Once you achieve the correct tension, there should be a big gap and sufficiant clearance. Only then, should you turn high limit screw inwards until the gap is around 1mm.

Last edited by trailflow1; 01-31-17 at 09:07 AM.
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