Hi All,

I need some help desperately and I can't seem to find a remedy anywhere. When setting the high limit it only moves a few millimeters out then stops. I notice if I push the shift lever it does still push out slightly past that point. Does this point to cable tension issues? Not tight enough? I can't really pull it any tighter and if I barrel adjust it rubs heavily in the middle chainring.

Would appreciate any help

Thanks!

Did you search the "old" FDER questions?

Without saying what type of system such as brand, # chain rings, shifters etc., one can only try to guess what you are talking about.
Start here from STEP ONE-
https://www.parktool.com/blog/repair-...ur-adjustments

The high limit is set with full cable tension, adjust the high limit, then pull on the cable on the downtube to make sure it is set correctly. If it doesn't get close to the high limit when upshifting then it is a cable tension issue. If, when you adjust it to adequately shift onto the big ring and it is still rubbing alot in the middle ring, it may be a derailleur alignment issue or you may just have to trim the shifter more often if you have the option. A properly set up triple shouldn't rub in any of the middle ring combos though except for possibly the two extreme ends of the cassette.

It's a Shimano Deore FD, 3x chainrings. Followed parktools and spent hours reading on forums trying different things.

It does seem to be a cable tension issue because if I increase tension by pushing down on the shift lever, it stops rubbing. How can I tighten the cable without using the barrel adjuster on the big ring? Or will that give the same rubbing issue on the middle ring?

I think you don't understand what the limit screws do.

Imagine you need to park your car between two others at the curb. The position of those cars determines how much room you have to move back and forth. If you move either car forward or back slightly, it'll affect how far your car has more or less room to move in that direction, but your car won't actually move there until you move it.

Likewise the limits. They determine how far the derailleur can move, but it's the cable movement (not tension) that moves it.

Applying that, if you want to move the derailleur farther out in high, you have to back off the limit a bit to make the room, then adjust (sighten/shorten) the cable to move the derailleur out.

Sorry for not making myself clear. The problem is not the limit screws but the fact that cage doesn't move far enough out to stop rubbing against the chain in the biggest ring. If I push on the shift lever it goes to where the limit screw is set but then just drops back a millimeter or so causing it to rub.

Going back to the car analogy, there's enough room for the cage to move out, but the cable isn't moving it. That's why I made a point of moving away for the term "tension" in describing cable adjustment. You need to shorten the cable, either with an adjuster if the bike has one, or by pulling it down a bit through the pinch bolt, so the cage is farther out when the lever clicks into position.

BTW-
One of the worst things in modern design and production, is the loss of a FD cable adjusters. Historically mtn bikes had adjusters on the levers, and road bikes on the frames, now many bikes don't have either. So, if your bike does not have a barrel adjuster, either on the lever, or on the frame someplace, consider buying an inline adjuster and putting on the handlebar to frame section of housing. This will make it easier to fine tune the cable length for optimal FD trim.

Now for some specifics that might help. I always adjust Shimano triple fronts for best trim on the middle chainring. Then adjust the inner limit to set the trim on the granny, since the cable is usually slightly slack there. Usually a correctly adjusted FD cage will be a bit outboard of perfect trim on the outer, and you'll pinch that back with the limit.

If the FD trims perfectly on the middle but is too far in on the outer, there's not much you can do, but this is abnormal, and means the lever isn't pulling enough cable. This is exceptional, but one trick you can try (after eliminating any possible cause) is to anchor the cable to the inside of the pinch bolt (between the bolt and pivot). This shortens the lever arm translating to more cage movement for any given cable movement. I don't suggest you try this remedy casually, it's strictly a last resort when ALL other possibilities are eliminated.

Thanks FBinNY. So just focusing on the middle chainring for the moment, I can't seem to get the chain to clear on both the highest and lowest sprocket at the back. If I trim to clear on the one side, it will rub on the other and vice versa. Could it be that the cage is just to narrow to accommodate the rear gears?

Am I understanding you correctly? Trim doesn't allow you to use all the rear sprockets without rubbing, it is there to stop rubbing in either end of the cassette. Trim up when you are rubbing in small sprockets, and trim down when you are rubbing in the high sprockets

Yes, the cage is narrow, which is why better Shimano shifters have extra clicks for fine tuning. Sram and Campagnolo don't have actual indexing FDs and allow the rider to trim the FD cage at any time.

If you cannot span the entire cassette from a single position, set the trim to just barely clear the with the sprockets that are actually used with either chainring. ie, the outer should just barely clear on the outermost, and clear with the middle rears though the inner one or two may rub (but you don't generally ride crossed over anyway, because it's hard on the chain). The middle should best clear with the middle and inner side of the cassette, and the granny is trimmed for the inner rear sprockets.

That should allow you to get all the combinations you'd normally use, though it may rub on ones you wouldn't.

BTW- this is a PIA to dial in trial and error so consider getting an inline adjuster if your levers or frame mounted cable stops don't have built in adjusters.

That's what I meant, it only rubs at biggest and/or smallest rear sprocket. I can't get it to not rub on both. I would have thought it's possible not to have any rubbing when on the middle chainring and any of the rear gears.

Would it be considered cross chaining if I'm in the middle chainring and on the biggest/smallest gear at the back? If that's bad on the chain I might just leave the rubbing as is, to warn me to change to higher/lower front gear.

Most people them the FD so the middle can be used with the middle and inner cassette sprockets, and don't plan on using the outer. But you can leave it that way if you expect to go to the granny rather than middle/inner combination. BTW- a bit of gentle rubbing once in a while in rarely used combinations is fine. Just don't have the cage rubbing in the gears you always ride. Before index many people would poorly trim the FD, and ride all day with it rubbing pretty hard.

I remember seeing them bring in repairs, with the FD cage worn all the way through, in some cases with a 5/16" section missing at the height of the chain on the ring. I always wondered how long it took, and how they couldn't hear it.