Evadd19

I have followed parktool and other guides regarding front derailleur adjustment, however even when cable tension is slack and cage is on lowest chain ring, the chain still rubs against the inner cage, I have fully tuned out the L limit screw which would otherwise bring the cage away from the chain towards the frame. Seems like my cage is just shifted away from the frame.

ClydeClydeson

great story.

Bill Kapaun

What's the rest of the story?
Which inner side?
What did you change?

blamester

What changed?
​​​​​​Just the derailleur?
The cranks?
You sure you are turning the right screw.

Evadd19

Sorry about the lack of detail but to reiterate, I tried to adjust the limit screws on the front derailleur first adjusting the lower limit screw. I had back out the L screw all the way so that the inner cage would stop rubbing against the chain side closest to the frame. But even after adjusting screw the chain still rubs with no further screw thread to play with. How could I get space between chain and cage for lower limit?

Hope this makes more sense. Additional info: inner cable was slack.

Bill Kapaun

Longer BB spindle. Or the correct crank for the BB you have.

You still don't give any history for this bike.
Did it function properly before or is it a bike you recently acquired with no known history?
IOW- What got you to where you are?

70sSanO

If you have removed the cable and it will not move any further, there are a few things you can do. Although it is odd to happen if nothing was changed.

The obvious is loosen the clamp screw and slightly rotate the derailleur. Adjust the H limit screw and make sure that everything shifts fine.

There are a couple of small tweaks, only minor rubbing, I’ve done, if I have changed something and can’t bring the derailleur in enough. I’ve never done these on an already well setup drivetrain.

The easiest is to remove the cage screw at the back of the cage that holds the outer and inner plates together and add a small washer. This is really just a minor tweak and is nice for just a bit of cushion.

I will look and see what the cage is hitting against and have been know to judiciously file that area if it appears that it won’t impact functionality.

If I’m using a FD that needs clamp spacers, I have on one occasion used a thicker than needed on the opposite clamp side and sanded the thickness on the cage side, blending in the middle to move the whole FD closer to the seat tube.

John

cyccommute 

I’ll leave the snark for others. If this is a new derailer install, the crank is probably too far out board for the derailer. You’ll need to move the crank inboard. If you have a square taper, that will mean you need a new spindle. A few millimeters smaller will probably do.

If this is an existing derailer, pull the derailer outboard with the cable slack and see if there is debris behind the derailer. Perhaps lubricate the pivot points and work the derailer until it frees up. Worst case, remove the derailer and soak it in mineral spirits.

Evadd19

Thanks a lot Cyccommute and John will give your solutions ago although I have checked for obstructions and lubed the derailleur. I don’t think I’ve explained properly from the start. I have a Carrara Vengeance 2017 (3 front chainrings) it was rubbing before and shoring wasn’t so smooth. I’ve only adjusted the barrel adjuster, pinch bolt and derailleur height. Without any wire tension and L screw fully out the cage is still too far out when selected to the smallest chainring thus causing chain rub with the inner cage. It seems to me the positioning of the cage is in a better position for the middle chainring rather than the smallest as it’s positioned more away from the frame. What do you guys think could help?

Crankycrank

Is the derailleur aligned properly, cage parallel with the chainrings?

Evadd19

Yes everything is straight

cyccommute 

It sounds like the spindle on the bottom bracket is too short. The bottom swing derailer your bike has can be a bit persnickety. That kind often can’t move far enough back and tend to rub, in my experience. A new bottom bracket is easy enough but a bit more work. You could also replace the bottom swing derailer with a top swing front derailer. I find the top swing can go a bit more inboard than the bottom swing. You need a bottom pull as well.

Evadd19

I appreciate your input but I do have a top swing derailleur still it lies outbound

cyccommute 

Did you replace the OEM front derailer? The original one was a bottom swing. Just to be sure we are on the same page, Top swing on the left, bottom swing on the right.



You can see the problem with the bottom swing. It can’t go inboard as far because it is trapped against the clamp.

If you have the top swing, you probably need a narrower bottom bracket.

cranky old road 

Did I miss when you stated where the chain is on the rear cogs when you have the rub?

70sSanO

First step is to put the chain on the middle chainring and a cog in the middle of the cassette and see how close it is to 90 degrees to the axle/hub. It doesn’t have to be a exact but it will give you and idea of the chainline.

Hopefully the chain will look like it is angled out at the cassette and you need to move the chain to a lower cog to square it up.

From the little I could find on your bike I think it has a SRAM square taper crank. Before you remove it try and figure out how much further out it has to sit to not rub on the lowest cassette cog in the small chainring. You are basically getting a bottom bracket with a wider spindle. But too wide and the derailleur may not reach the outer ring.

The one caveat of all this has to do with a bent frame. Now since it is aluminum, you can’t (shouldn’t try to) bend it back. But that could be a reason why you are getting chain run. If it is bent, it is up to you whether you want to pursue a wider bottom bracket spindle.

John