Front Derailleur H-Limit Adjustment
 

I need to adjust the h-limit screw since there’s chain rub when on the big ring and smallest cog. I can do this without having to do the whole fd tune up, right? L-limit is set ok and the shifting is ok as well. Bike mechanic didn’t set the h-limit properly last time i had it tuned up. I now do the bike tinkering on my own. While i’m confident doing the rd tune up, i find the fd tune up a bit tricky, especially setting the cable tension correct. Cable tension is currently set ok, shifting is fine, so i don’t want to tinker with it unless necessary.

Sure, back it off 1/4 turn, see if it helps. You can always turn it back.

If limit doesn't work, you need to check the mounting position and see if it has slipped or just needs an adjustment to be correct.

Great! Will do it later.

Limit’s ok, mechanic just did not set the h limit correctly last time he tuned it up. Been riding like that for a while, avoiding the big ring-smalllest cog combo. I’ll correct it later and check anyway as you said.

If you get the limit set ok and the derailleur looks in good alignment, but you still get some rubbing and you don’t want to keep futzing with the shifter to dress it while you’re riding, you could try something I think I heard on GCN: Use the next size narrower chain. If it’s possible to do that, it might get you just that bit of extra clearance you need. I’ve done it and it’s helped my situation.

It's possible that setting the H limit screw to not rub in big-big combination will make it difficult to shift up in the front. What I usually do:

1. Make sure the derailleur cage is at the right height and is aligned perfectly with the big chainring.
2. With the chain in big-big combination, loosen the H screw until it starts to rub, then tighten 1/4-turn.
3. Try shifting the front down and up a few times. If it shifts okay, you're done.

If it doesn't shift okay:

1. Unscrew the H screw a bit, try shifting up and down.
2. Repeat until it shifts up easily.

Now use the cable tension adjuster to eliminate any rub in big-big:

1. Shift into big-big combination.
2. Loosen cable adjuster until rub is gone.

This method also makes it easier to shift up and down the front, as you're not pushing hard against the H limit to get the shifter on and off the "big ring" click.

His rubbing is with big in front, small in back, not big-big

Ugh! Can't read, obviously.

Adjusting to prevent rub in big-small is quite straightforward.

(Maybe someone else will benefit from my instructions on adjusting for big-big)

I will. I’ll try that when i do a full fd tune up. I’m not yet confident with the fd tune up compared with the rd tune up. It’s the trimming that confuses me a bit. I’ve watched some vids who said there’s no need to adjust for the trimming, but today when someone gave me a link to the shimano manual, it says there is a trimming adjustment. Haven’t read it thoroughly yet, will do later.

The newer type Shimano FD makes my head hurt. I can't make any sense of what's going on and have to follow the instructions step-by. Each time. There's definitely stuff I like about the way it works, just wish I could understand why. :foo:

Based on my own experience, you can chase adjustments around on the FD. I would recommend that you consider a full "fresh" installation if/when you feel it's not working right: remove the chain and cable then follow the manufacturer's or Park Tool instructions from Step A, not skipping any steps even if you feel you can. Height, alignment, limit screws without the cable attached, then attach the cable and get it to shift to both chainwheels without the chain and observe the limits - then see how it works pedaling with the chain and tweak accordingly. It's really an easy mechanism, but you can get messed up by trying to adjust something when really it's something else that's needed. Once you've got a good idea of the A-Z of installing and adjusting, you can better home in on what needs to be done.

How about the trimming? How do you go about setting this? Some vids say no need to set or adjust it. Manual said if you try and test the trim and it instead shifts fully to the lower chainring, you adjust the h limit counter-clockwise by 1/8 turn.

I found the Park site very helpful. Originally posted by another member: https://www.parktool.com/en-us/blog/...?area%5B%5D=52

Thanks!

I avoid all cable tension issues by using friction shifters. I own several bikes with indexed shifters that work fine but I prefer the simplicity and function of friction. All you need do is make sure the derailleur is mounted properly and set upper and lower limits. If there is any rubbing after the shift, you simply adjust the trim using the shifter. I can see the benefits of indexed shifting if racing, but for everything else friction is vastly superior IMHO.

Obviously not helpful for the OP.

Another good source of videos is Art's Cyclery's "Ask a Mechanic":

https://www.youtube.com/results?search_query=art%27s+cyclery+shimano+front+derailleur+setup

Could be if he wants to simplify bike maintenance. Absolutely as helpful as a post judging another post as useless.

So you're advocating his shopping for legacy equipment to replace his current equipment as a way to solve his shifting problem? About as helpful as suggesting he simplify maintenance by just walking.

Just found this on youtube literally a few minutes ago, hehe. Was just about to post it here too. This trim adjustment is what’s confusing to me why i’m afraid to tinker with the fd. Tried looking for vids on youtube but found none about trim setup, until that Art’s Cyclery vid. I’ll give this a try for sure. Sweetsbench mentioned trimming, but did not do any trim setup.

Your problem probably isn’t a limit screw problem. Shift to the big ring and push on the shift lever. If the derailer won’t move outward, you can adjust limit screw outward a little. But if you see derailer movement when you push on the lever, it’s a cable problem. Your cable isn’t tight enough to move the derailer over and hold it there. This is the most likely problem.

Your derailer could also be misaligned. Shift so that the outer plate of the derailer is aligned with the chainwheel. The outer plate should be parallel to the chainring. If it isn’t, you’ll need to loosen the derailer and move the tail so that it is parallel to the ring.

Wow. Know what, now that you mentioned it, there is indeed derailleur movement when i push on the lever when i’m on big ring. Not sure how much exactly, but maybe a mm or two. I actually thought then that this is part of trimming, but there is no click. When on the small ring and there’s chain rub while on the smaller cogs, i’d push it, and it’ll give me a few mm so there’s no chain rub. So this is cable problem? What’s the fix? Just tighten the barrel adjuster? In Calvin Jones’ fd adjustment, after the h-limit setup, he did fd indexing ( which i don’t see in any fd tune up tutorials) where while on the big ring, he intentionally caused movement on the derailleur via the barrel adjuster, then readjusted it until there is no more movement. Is this the fix? Cause i also thought of doing that as a possible fix.

As for the fd plate, it is aligned, no prob there at all.

i don't think all FD shifters have trimming. yours may not. my older ones don't but my newer ones do.

5800/6800/9000 (the 1st 11-speed generation) was the first Shimano generation to have trimming. Generations before that didn't.