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FD-6500 - Should Cable Contact Derailleur Body

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FD-6500 - Should Cable Contact Derailleur Body

Old 05-01-23, 11:21 AM
  #1  
Harold74
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FD-6500 - Should Cable Contact Derailleur Body

I've got one of these derailleurs on a bike with downtube shifting (friction up front). Over time I noticed that, when in the small chainring, the front derailleur would ghost shift towards the right unless I really tightened up the friction on the lever for the front derailleur. I tore the bike down to the frame and rebuilt it recently but, sadly, did not properly document the original derailleur setup.

I've diagnosed the source of the "problem" as being a roller in the derailleur bumping into the shift cable such that the shift cable deflects like a bow and tends to push the derailleur back towards the right. I've tried to illustrate this condition below.

Originally, thought that surely the derailleur would not be designed for this contact to take place. I have both older, and more modern derailleurs where this doesn't happen. On the other hand, I can think of no way to adjust the derailleur setup to prevent cable contact with the derailleur body. Consequently, I'm starting to wonder if the cable contact might actually be some kind of design feature.

Perhaps the idea is to try to keep the cable pull force more consistent as the derailleur moves through it's shifting arc?

So my fundamental question is this: should my shift cable be contacting the front derailleur body like this?


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Old 05-01-23, 11:45 AM
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This der was intended to have the cable pass by the anchor bolt above it, like the grey one and not what I think you did. If your shift lever were to be an indexed one the cable would be routed soiti ran over the little tab on the arm at about the 8: position WRT the anchor bolt. Again like the grey image shows. But with friction there's nothing wrong routing the cable to either side of the bolt (as long as the clamping bit is achieved), except for changing the leverage the lever has over the der. By clamping the cable on the closer to the arm pivot side of the bolt (the blue) the lever has to have more friction resisting the added cable tug. Moving the cable to the above the bolt routing will improve the lever's ability to maintain the der's position but will also mean that the lever will have a greater amount of rotation to wind up the greater cable movement length. Andy
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Old 05-01-23, 11:49 AM
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BTW those parallelogram pivot bolts (called "shoulder screws") tend to come loose and allow more flex and slop to the cage's travel. Use a good sharp/square ended 3mm hex wrench as the socket is shallow. I generally add a drop of lube and work the der a bit before tightening the bolts. Andy
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Old 05-01-23, 01:06 PM
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@andy: thank you for your responses thus far, I'm grateful for you input.

Originally Posted by Andrew R Stewart
This der was intended to have the cable pass by the anchor bolt above it, like the grey one and not what I think you did.
I have the derailleur set up just like the one shown in the grey, schematic sketch. I also have the cable running from the bottom bracket cable guide at the position furthest left. I'll try to post some photos of the setup sometime soon.

When setup as intended, is it your opinion that the cable should NOT come into contact with the derailleur body? While I'm interested in any advice that you, or others, may have to offer, this is my fundamental question. If the cable contact is not a design feature, then I'll focus my efforts on trying to rectify the situation. If it IS a design feature, then I'll just live with it or find another derailleur.
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Old 05-01-23, 01:15 PM
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Cable contact with the pivot bolt is not an intended design for this family of ders. But don't trust my saying so. Just try it and see if things work ok. It won't hurt your bike to try. If you decide the function is worse then go back. Andy
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Old 05-01-23, 01:32 PM
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I have a 6500 der. on a bike that's done around 20K miles and is setup like in the photo above. Drove me crazy trying to figure out why the cable rubbed on the derailleur but that's the way it was designed and has worked flawlessly and without sawing into the der all this time but I do have the STI indexed shifters which may do more to prevent the der from moving to the right when in the small chainring but not sure about that. Shimano's official mounting instructions. Shimano_Ultegra_6500_Front_Derailleur_Instructions.pdf (sjscycles.com)
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Old 05-02-23, 12:20 AM
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I can envision scenarios in which the cable may come into contact with the derailleur itself. Not by design, I would think, but incidentally depending on the exact setup (frame geometry, FD mounting height, BB shell cable routing path). Lowering the FD mount height will increase the angle of the cable (moot if the FD is already at the correct height for the chainrings), as would routing the shifter cable through the NDS-most channel under the BB shell, but maybe still not enough to matter for OP.
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Old 05-08-23, 11:45 AM
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Originally Posted by Crankycrank
I have a 6500 der. on a bike that's done around 20K miles and is setup like in the photo above. Drove me crazy trying to figure out why the cable rubbed on the derailleur but that's the way it was designed and has worked flawlessly and without sawing into the der all this time but I do have the STI indexed shifters which may do more to prevent the der from moving to the right when in the small chainring but not sure about that. Shimano's official mounting instructions.
Thanks for that. I'm grateful for everyone's input but it is especially nice to hear that I'm not alone in experiencing the problem. Either there is contact by design or we both suck at setting up derailleurs.
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Old 05-08-23, 11:50 AM
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Originally Posted by tFUnK
I can envision scenarios in which the cable may come into contact with the derailleur itself. Not by design, I would think, but incidentally depending on the exact setup (frame geometry, FD mounting height, BB shell cable routing path). Lowering the FD mount height will increase the angle of the cable (moot if the FD is already at the correct height for the chainrings), as would routing the shifter cable through the NDS-most channel under the BB shell, but maybe still not enough to matter for OP.
I see what you're getting at and I agree. Some related thoughts of my own:

1) The only frame oddity that I'm aware of is that the seat tube is a bit slacker than other road bikes. That said, the difference is slight and I'd think that this would be mitigated by the angle of the FD rotating in space to match the seat tube.

2) The mounting height is proper for 53/39 rings which was the original setup and, given the age of the bike, likely the originally anticipated setup when the bike was spec'd new.

3) Regarding the bottom bracket routing, I'm in the most advantageous channel as it stands. To further exploit that, I'd have to either drill a new BB hole or get my hands on a plastic guide thing with the channels differently located.

Thanks for your contribution.
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Old 05-29-23, 11:37 AM
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I promised a photo of the real condition and never followed through on that since:

1) I felt as though my question was adequately answered and;

2) I struggled to get a meaningful photo of the condition with the wheels on. Too many shadows...

I had the wheels off out in the sunshine this weekend and took the opportunity to snap a couple of decent photos. You can see how slight the effect is.

Follow up question:

If the barrel guard thing is not a design feature meant to alter shift leverage, what is the purpose of it? Aesthetics? Half assed attempt to keep whatever's under there clean and dry? I ask because I'm tempted to remove the barrel guard to smooth out my FD friction shifting issue. The Ultegra FD is a nice part and I'll likely end up downgrading to a 105 5700 if I'm stuck with the contact issue and am unable to solve it with a reasonable amount of friction in my FD downtube shift lever. That seems like a waste of sexy kit.


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Old 05-29-23, 11:54 AM
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just leave it alone and go ride your bike.... once you're done doing whatever you're doing..
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Old 05-29-23, 11:56 AM
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I think that barrel guard is there to keep dirt out of the spring ?

I would not worry about it. What exactly is the problem you are trying to solve ? High lever effort ? long lever travel ? poor shifting ?

the fact that the cable drags on the derailleur is nothing to worry about. IMHO.

/markp
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Old 05-29-23, 12:42 PM
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Originally Posted by Harold74
I promised a photo of the real condition and never followed through on that since:

1) I felt as though my question was adequately answered and;

2) I struggled to get a meaningful photo of the condition with the wheels on. Too many shadows...

I had the wheels off out in the sunshine this weekend and took the opportunity to snap a couple of decent photos. You can see how slight the effect is.

Follow up question:

If the barrel guard thing is not a design feature meant to alter shift leverage, what is the purpose of it? Aesthetics? Half assed attempt to keep whatever's under there clean and dry? I ask because I'm tempted to remove the barrel guard to smooth out my FD friction shifting issue. The Ultegra FD is a nice part and I'll likely end up downgrading to a 105 5700 if I'm stuck with the contact issue and am unable to solve it with a reasonable amount of friction in my FD downtube shift lever. That seems like a waste of sexy kit.

That doesn't look bad at all, wouldn't worry about it. When you begin the shift, the cable will move away from the contact point as the arm moves and the contact point also moves away. So, only the initial small movement at the start of the shift has any affect. Should have minimal rubbing & friction.

Whether you have contact, is frame dependent, one of my frames has a little contact at the rivet (closer to the camera in your picture), and another frame has no contact at all.
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Old 05-29-23, 01:30 PM
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Originally Posted by KCT1986
That doesn't look bad at all, wouldn't worry about it.
Thanks for your response. However, I do intend to resolve this, at least to my own satisfaction. As it stands, I have to either:

1) Tighten the FD shifter down so greatly that it's "too tight" from my perspective OR;

2) Accept that the FD drifts to the right and will require intermittent adjustment as I ride when I'm at the leftmost position of the low ring.

I dislike both of those options and will get a new FD to solve the problem if there's no other way.
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Old 05-29-23, 02:10 PM
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Are you using this FD with a 6500 crank and bottom bracket?
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Old 05-29-23, 02:21 PM
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Originally Posted by rccardr
Are you using this FD with a 6500 crank and bottom bracket?
Originally Posted by shelbyfv
You might look for a 9 or 10 speed DuraAce FD. I think that will resolve it.
The crank is Dura Ace 7700.

Are you gentlemen suggesting that there is some geometric property of the DA crank / BB that makes it incompatible with the Ultegra 6500 FD? To remove the contact, I'd think that property would have to be one of:

1) The FD gets mounted lower and/or.

2) The chain line on the DA 7700 is further out board.
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Old 05-29-23, 03:56 PM
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Originally Posted by Harold74
The crank is Dura Ace 7700.

Are you gentlemen suggesting that there is some geometric property of the DA crank / BB that makes it incompatible with the Ultegra 6500 FD? To remove the contact, I'd think that property would have to be one of:

1) The FD gets mounted lower and/or.

2) The chain line on the DA 7700 is further out board.
How high is the FD? I position mine with the outer plate about a mm above the large chainring. The Ultegra FD should work fine. That barrel is the spring dust cover. On my bike the cable is 1 mm from the dust cover when the chain is on the small ring (both FD and crank are 7700).
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Old 05-29-23, 04:09 PM
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you know what i noticed? you don't even have a chain on the bike, and the Der. is set too far inwards which will allow the chain to derail to the frame side.

oh, and the cable isn't actually touching the inner pivot link, so you're just speculating about something that every advisor here is telling is not a problem.

i've set up dozens of bikes with front der. cables touching all sorts of things... the cable rides ON THE BOTTOM BRACKET or RIDES ON A GUIDE on top of the bottom bracket... and also, the CABLE HOUSING is in Direct Contact with the Cable for FEET, not a tiny point.... in your case, the actual contact POINT is ridiculously tiny, and the second you put tension on the cable to shift, that contact ENDS..

You have been Fretting endlessly about a "problem" that only exists IN YOUR MIND and you are totally ignoring, even arguing with, the advice you claimed to have been seeking.... You just went so far as to PRE-ARGUE what hadn't been said.

that's messed up.


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Old 05-29-23, 04:23 PM
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Originally Posted by smd4
How high is the FD? I position mine with the outer plate about a mm above the large chainring.
Same here.

Originally Posted by smd4
That barrel is the spring dust cover.
Excellent. I shall disappear the dust cover then.
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Old 05-29-23, 04:28 PM
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Originally Posted by Harold74
Same here.



Excellent. I shall disappear the dust cover then.
Well, it is there for a reason, but even the DA 25th Anniversary FD seems to have dispensed with itů
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Old 05-29-23, 04:35 PM
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Originally Posted by maddog34
you know what i noticed? you don't even have a chain on the bike, and the Der. is set too far inwards which will allow the chain to derail to the frame side.
I look into it. However:

1) To my knowledge, I set the derailleur up per the instructions of Shimano and my bike mechanics books.
2) This setup has been working flawlessly for a couple of hundred rides now. No inner chain drops yet, just the annoying thing where the contact keeps the FD shifter from staying put.

Originally Posted by maddog34
oh, and the cable isn't actually touching the inner pivot link, so you're just speculating about something that every advisor here is telling is not a problem.
The cable is most definitely touching the thing that others have called the "dust cap". That is the source of the shifting problem that I've been having.

Originally Posted by maddog34
i've set up dozens of bikes with front der. cables touching all sorts of things... the cable rides ON THE BOTTOM BRACKET or RIDES ON A GUIDE on top of the bottom bracket... and also, the CABLE HOUSING is in Direct Contact with the Cable for FEET, not a tiny point.... in your case, the actual contact POINT is ridiculously tiny, and the second you put tension on the cable to shift, that contact ENDS.. You have been Fretting endlessly about a "problem" that only exists IN YOUR MIND and you are totally ignoring, even arguing with, the advice you claimed to have been seeking....
I don't get the impression that you understand what my problem truly is. The problem isn't so much the contact between cable and dust cap -- although I find that strange too -- but, rather, that said contact is pushing the FD to the right and causes rubbing when I'm in my small chainring and large cassette cogs. It causes my FD friction shifter to ghost shift sort of (no actually gear change occurs).
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Old 05-29-23, 04:52 PM
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Originally Posted by smd4
Well, it is there for a reason, but even the DA 25th Anniversary FD seems to have dispensed with it…
Yeah. Based on the diagram below, I believe that the thing residing below the dust cap is just the spring that you pull against when you move the FD upwards. And, if that's the case, then I suspect that the cap is just either:

1) A cosmetic thing.
2) A safety feature to keep the FD cable from getting stuck in the spring (maybe in conjunction with a leverage improvement).

I commonly see utterly filthy RD springs that function flawlessly.

I'll pull the cap off and give it a go unless it feels as though the cable and spring are too close for comfort. I doubt that a snapped FD cable would do me any real harm but, who knows, maybe it could slash my tire or somehow get caught in the spokes.

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Old 05-29-23, 08:07 PM
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The cable guide under the BB may have two positions for the mounting bolt. See if you can move the cable guide to the left to produce more clearance.
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Old 05-30-23, 12:51 AM
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Originally Posted by Harold74
The crank is Dura Ace 7700.

Are you gentlemen suggesting that there is some geometric property of the DA crank / BB that makes it incompatible with the Ultegra 6500 FD? To remove the contact, I'd think that property would have to be one of:

1) The FD gets mounted lower and/or.

2) The chain line on the DA 7700 is further out board.
My second question is whether you are using the correct BB. DA 7700 was available with two, one for doubles and one for triples. They are identical except for width. If your double is mounted on a triple BB, it would sit further out from the frame than optimal.

6500 should be fully inter-group compatible with 7700.
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Old 05-30-23, 06:04 AM
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Originally Posted by rccardr
My second question is whether you are using the correct BB. DA 7700 was available with two, one for doubles and one for triples. They are identical except for width. If your double is mounted on a triple BB, it would sit further out from the frame than optimal.

6500 should be fully inter-group compatible with 7700.
I replaced the OEM BB last summer with another of the same proportions. I think that the original was Ultegra and the replacement was 105. I'll see if I can find the OEM BB in my parts bin to verify the width.

If I did have a triple BB in there, and that would push the crank outboard as you say, would that not reduce the likelihood of contact rather than increase it?
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