Should I accept the chain rubbing on the front derailleur?

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John_S
Posts: 329
Joined: 16 Sep 2014, 10:34pm

Should I accept the chain rubbing on the front derailleur?

Postby John_S » 13 Jun 2018, 12:04pm

Hi All,

I've currently got a problem, mainly of my own making, with the front derailleur on my 2016 Kona Roadhouse bike ( http://2016.konaworld.com/roadhouse.cfm ).

The drive train components include the following although I can’t see which specific model codes apply to each part.
Front derailleur: Shimano 105
Rear derailleur: Shimano Ultegra
Rear cassette: Shimano 105 11-32t 11spd
Front Chain Rings: 34/50t

Now up until yesterday I'd never made any adjustments at all to the gears and all was working pretty much fine. However I had noticed that at the extremes of the cassette I would get some noise when say in the small ring and 1st & 2nd gears or the big ring and the 10th & 11th gear cogs on the rear cassette.

In all honesty I don’t really use the extremes at either end of the cassette very often because I live in Norfolk and although there are some lumps to go up & down it’s not as if we have long mountain ascents or descents. However when going downhill I would sometimes get into either 10th or 11th and always notice some noise coming from the drivetrain. Therefore when cleaning the bike I decided to look at this and on inspection I noticed that the chain was rubbing on the derailleur when at the extremes of either the easiest or hardest gears.

Now in hindsight I wished that I’d left things well alone without touching a thing and had just lived with the noise at the extremes of the cassette, given that I hardly ever use them, because other than that in the middle of the cassette everything was working absolutely fine. Unfortunately I didn’t do this and I watched a few videos including the following and decided to have a go at adjusting the front derailleur to try and get 1mm of distance in-between the chain and the derailleur as recommended in these videos.

https://youtu.be/Ea03ChN-7Vg

https://youtu.be/ZNG7g83lI-s

https://youtu.be/sQkvCmg1ckM

Now starting with the chain in the small chain ring and in 1st gear on the cassette I tried to use the limit adjustment screw to move the derailleur but it didn’t go anywhere at all. At first I thought maybe I was using the wrong limit screw and so I tried the other but again nothing moved. On the videos that I’d watched it said that this may happen because the cable tension is too tight and if this was the case I should undo it. Therefore I undid the bolt on the cable clamp to let the cable go completely loose and then I was able to adjust the derailleur to get 1mm of distance in-between the chain and the derailleur when in the small ring and in 1st gear.

However from that point it’s gone wrong because having put the cable back into place and secured it with the bolt the front derailleur will no longer put the chain into the big ring. Now before I undid the cable I made a note of how much cable was showing above the clamp at it was 5.5cm. However even when using a pair of pliers to try and grip the cable to pull it tight the most that I can get above the clamp is about 5.2cm. Therefore I’m wondering it this might be part of the problem. The videos said that I could use a barrel adjuster on the cable to make adjustments. However on my bike where the cable is secured to the frame at the top of down tube the bare cable enters a cable outer at the point where there is a braze on but this doesn’t seem to move/twist/turn at all. Further up the cable and roughly half way in-between the top of the down tube and where the cable goes on into the shifter there is a very small barrel which spins. I tried turning this to see if it would help at all but I couldn’t detect any movement or change in the slightest. Therefore I don’t know whether this is a barrel adjuster or not because if there was any movement I couldn’t detect it but either way it hasn’t helped.

I’m now stuck in the small chain ring only and so I’m probably going to admit to defeat due to my mechanical ineptitude and take it to a LBS for them to take a look at.

Now at worst I’d like them to get it back to how it was before I touched it but ideally to a point of improvement on before whereby there is no longer any rubbing of the chain against the derailleur in the extremes of either the easiest or hardest gear.

However last night when continuing reading on this subject I read this on the Park Tool website ( https://www.parktool.com/blog/repair-help/front-derailleur-adjustment#article-section-9 );

“9. Front Derailleur Performance
The front derailleur should shift the chain between chain rings without throwing the chain off the extreme outer and inner rings. It is possible that the front derailleur will rub the chain slightly even on properly adjusted bikes. This is likely on some bikes when riding in the largest sprocket in front and the smallest cog in back.”

Now I wish that I’d read this before I ever tried to adjust anything at all because should I just have accepted that the chain will rub against the derailleur when in say 1st or 2nd and 10th & 11th gears and so even after my bike has been to the LBS this is the best situation that I can expect to have or should it be possible to get the front derailleur setup without the chain rubbing on it?

Thanks to anyone for any advice!

John

chris_suffolk
Posts: 390
Joined: 18 Oct 2012, 10:01pm

Re: Should I accept the chain rubbing on the front derailleur?

Postby chris_suffolk » 13 Jun 2018, 12:25pm

If you can get it back as it was, then...

On my bike with Tiagra STI shifters, there is a setting on the shifter to move the front derailleur a tiny amount depending on whether iI'm running on the large or small cogs on the rear. It's quite hard to miss unless you know it's there, but just press the left shifter gently until it clicks, but doesn't cause the chain to switch rings. This just adjusts the front a tiny bit and is designed to avoid rubbing in the manner you describe.

First however you have to get it back as it was.

Brucey
Posts: 35906
Joined: 4 Jan 2012, 6:25pm

Re: Should I accept the chain rubbing on the front derailleur?

Postby Brucey » 13 Jun 2018, 12:27pm

to fix your problem;

1) anchor the cable anywhere (with the bike in the workstand)
2) whilst pedalling by hand, pull the cable sideways (on the bare run on the DT) so that the chain goes onto the big ring.
3) stop pedalling; the front mech should now hang up on the big ring and the cable should be slack
4) adjust the cable to where you started
5) trim out using the inline barrel adjuster (*) and the stop screws.

(*) best if you free this off (it is most likely the thing in the cable run, and it is probably seized) first I guess

Running big-big or small-small is not recommended; not only are you likely to get rubbing but running the chain at those angles isn't good for it.

BTW if you have the correct STI shifters for 'road' mechs they should have 'trim clicks' in the shifters so that you can avoid the worst of the rubbing. With bar end shifters etc you have to trim manually.

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

flat tyre
Posts: 466
Joined: 18 Jul 2008, 1:01pm

Re: Should I accept the chain rubbing on the front derailleur?

Postby flat tyre » 13 Jun 2018, 7:10pm

If set up correctly the Shimano 11 speed FD will rub at one end or the other, unless you use the trim click on the shifter. I find the 11 spped takes a bit of care to get it adjusted correctly and it's best done by following the instructions on the shimano website (see http://si.shimano.com/pdfs/dm/DM-FD0002-05-ENG.pdf.)

John_S
Posts: 329
Joined: 16 Sep 2014, 10:34pm

Re: Should I accept the chain rubbing on the front derailleur?

Postby John_S » 13 Jun 2018, 11:40pm

Hi All,

Thanks for the all of the messages which I'm just reading now after I'm home from work.

I actually took my bike to a local shop today and the mechanic there is great and solved the problem really quickly there and then making it look easy when I'd been struggling with it.


Hi chris_suffolk, thanks for your message and if only I'd known about the trim function in the first place I probably could have saved myself a whole load of hassle. The gears were pretty much fine apart from the slight rubbing at the extremes of the cassette at both ends of the spectrum in 1st & 2nd plus 10th & 11th and perhaps I could have managed/sorted this issue had I have known about the trim function. I guess that it just exposes my lack of knowledge about Shimano STI levers. Not that there's much to be said in order to defend myself but despite having been cycling for over 30 years I've not had many bikes nor am I mechanically minded. My first proper bike was a Raleigh Mustang MTB and that had friction shifters and that was followed by a Raleigh Apex MTB which had index shifters but I can't remember major problems from back then. After that I picked up a second-hand Trek 7.1 FX before getting my first drop bar bikes when I was in my 30's which was a Genesis Day One Alfine 8 so that had a Shimano Alfine 8 IGH and a bar end shifter. This bike, the Kona Roadhouse, is the first drop bar road bike with STI levers that I've had. Therefore I don't really have much experience with or knowledge of STI levers but the messages received on here have really helped!


Hi Brucey, many thanks for the step by step guide which is really useful! Although the mechanic a the LBS has fixed this now I'll keep this just in case I had to work on the from derailleur again and hopefully if other people search for something similar they'll find this as well.


Hi flat tyre, thanks for the advice and the the link that you've sent.


Thanks to everyone for the help & advice that you've sent which is really handy and so much appreciated.

Cheers,

John

esuhl
Posts: 115
Joined: 22 Mar 2017, 3:20am

Re: Should I accept the chain rubbing on the front derailleur?

Postby esuhl » 14 Jun 2018, 1:20am

I've been cycling for a few years now, and the MAIN thing that makes cycling frustrating (for me) is poor gear changes.

The best thing I ever did was learn how to adjust the front and rear gears fairly accurately. It's a bit daunting the first time when you don't really know the best way to do things, but with just a little bit of experience and practice, you get the hang of fine-tuning it. If it helps in the future, this is my technique:

Align the mech itself
Shift the chain so it's on the pair of inner gears, then the pair of outer gears, and compare the gap between the chain and the mech in each position -- it should be the same at both extremes. If the chain is too close on one side, shift to the smallest front gear (so the gear cable is slack), then loosen, align, and re-tighten the front mech accordingly. Then check the alignment again, and repeat if necessary.

You might also want to check the height of the front mech in relation to the chainring -- there should be a millimetre-or-so gap between the bottom of the mech and the teeth of the large gear. (Have a look at photos online.)

Adjust the H/L screws
Shift to the inner-most REAR gear, and shift the front gears up-and-down to the inner-most gear. Keep loosening the relevant High/Low screw on the gear mech until the chain falls off when you shift down. Then tighten it by a 1/2 or 3/4 turn so you can shift reliably without the chain falling off. Do the same for the outer gears. N.B. It helps to loosen the gear cables (by shifting down) first so there's nothing pushing against the end of the screws.

Barrel adjustment
Once that's done, you just need to fine-tune using the barrel adjusters. You'll need to shift up and down a few times to even-out the tension in the cable after making an adjustment (which is why you might not be seeing instant changes). Then check again.

Rear gears
Rear gear adjustment is pretty similar, but the dérailleur mech is attached to a hanger that's designed to bend easily (to prevent damage to the mech itself). If that gets bent out of shape and the rear gears aren't aligned with the mech's jockey wheels, you'll either need a new rear hanger, or a tool to re-align it like this:

https://www.amazon.co.uk/Park-Tool-DAG- ... B010T6L22E

Hope this helps. :-)

John_S
Posts: 329
Joined: 16 Sep 2014, 10:34pm

Re: Should I accept the chain rubbing on the front derailleur?

Postby John_S » 15 Jun 2018, 1:56pm

Hi esuhi,

Thanks for your message which is much appreciated! Whilst my bike is now fine following the work by my LBS I will be now more equipped to deal with a similar problem next time with the advice from you and others above.

Thanks again to all for taking the time to help!

John