Chain Rub Front Derailleur

maklabouhlel · 6 Jul 2015 at 04:12

I was wondering if someone could give me some advice please. I've got a road bike with a 105 front derailleur and whenever the chain is in the smallest outer three cassette sprockets then there is chain rub with the outer plate of the front derailleur in both chainrings. I tried adjusting the outer limit screw but to no avail. Thanks in advance.

mattyfez · 6 Jul 2015 at 06:40

Is the front derailleur in line with the chain, I. E. Does the bracket need rotating on the seat post slightly. May have worked lose and twisted around slightly or been knocked?

When you say the H limit screws to no avail, can you see it moving the cage, and it's not moving out far enough?

eXist · 6 Jul 2015 at 07:38

should be an inline adjuster somewere on your front gear cable, turn it anti clockwise to tighten the gear cable a little, also put your limit screws to were they sat before.

neil_g · 6 Jul 2015 at 08:13

sounds like it just needs a little more cable tension.

either (with the front derailleur in the smallest cog) undo the cable nut on the derailleur and pull through any slack. or use the adjuster on the shifter.

limit screw probably wont help here.

dodg3rman · 6 Jul 2015 at 08:50

Doesnt 105 have a trim function for the last 2 or 3 gears ?

FrenchTart · 6 Jul 2015 at 09:15

Exist and neil_g have got it.

@dodg4rman - this isn't a situation where you would use the trim feature.

maklabouhlel · 6 Jul 2015 at 14:13

mattyfez said:
Is the front derailleur in line with the chain, I. E. Does the bracket need rotating on the seat post slightly. May have worked lose and twisted around slightly or been knocked?

When you say the H limit screws to no avail, can you see it moving the cage, and it's not moving out far enough?

I'm not at home but I didn't notice it moving the cage. I did quarter anticlockwise turns until I reached 5 full turns. By this time, the chain would not move over to the big ring. I reversed the turns and the chain now moves over to the big ring. I'll try adjusting the cable tension later. Thanks guys.

maklabouhlel · 6 Jul 2015 at 18:05

I tried tightening the cable but the bolt snapped.

So now I need a new bolt/nut. Is it a standard part or does it have to be Shimano specific?

FrenchTart · 6 Jul 2015 at 18:22

You should have been tightening with the barrel adjuster - you didn't need to tighten the bolt that holds the cable in place.

I imagine most LBS will have spares they can give you for free/a few pounds.

maklabouhlel · 6 Jul 2015 at 18:23

Thanks.

maklabouhlel · 6 Jul 2015 at 19:12

FrenchTart said:
You should have been tightening with the barrel adjuster - you didn't need to tighten the bolt that holds the cable in place.

I imagine most LBS will have spares they can give you for free/a few pounds.

The cable looked a little loose so I thought I would tighten it. I couldn't tighten any further with the cable adjuster.

neil_g · 6 Jul 2015 at 22:22

If it takes more than a couple turns of the shifter/inline adjuster then its best practice (in my opinion) to undo the cable nut. The adjuster is for fine tuning not tightening a sloppy cable.

Snapping the bolt though? I know shinano like their chocolate bolts but cable clamps aren't normally those

maklabouhlel · 7 Jul 2015 at 00:39

When I get my new bolt and tighten the cable, what position should the cable adjuster be in?

arknor · 7 Jul 2015 at 01:44

he says what gears the chain should be on, how your barrel adjusters should be etc

He probably doesn't cover how to use the trim on shimano 105 though