Front Derailleur Help

[Hop3y]

My bake has been making a strange rattling and I have managed to find the source of the problem. My chain (whilst the front gear is on the middle cog) scrapes alongside the front derailleur whilst its in certain gears. The derailleur isn’t bent or anything, I think it might just need some cables either tightening or loosening. What’s the best way to go about it rather than paying through the nose for a service?

 

[raleighnut]

On the middle ring of a triple the only adjustment is in the tension. try tightening slightly first (as its most usual for cables to stretch) but not much before you try it until its right for the whole centre of the block, it is possible to get the whole cassette sometimes but more usual to get slight rub on the 2 outer rings.

 

[Hop3y]

Yeah, its not the whole cassette but it is the 2 outer rings... is that normal then?

 

[raleighnut]

Depends on how tightly the front mech runs to the chain and which chain you use, but that's pretty standard as you shouldn't really use those combinations. (I do know we all grab them sometimes)

 

[Brommyboy]

Try adjusting the lever when in gear - there is usually a small amount of movement for each chain ring setting.

 

[Hop3y]

Tried it and it doesn't seem to be working!

 

[mrandmrspoves]

Also look at whether the derailleur is running parallel with the chain. If not, the position of the derailleur may need adjusting slightly.
Assuming the derailleur does not need repositioning, if the chain is rubbing on the inner side of the derailleur (side nearest to the frame) the cable tension needs loosening slightly. If the chain is rubbing on the outer side of the derailleur the cable needs tightening slightly. All the above assumes that you are riding small chain ring to largest sprockets, middle chain ring to middle sprockets and largest chain ring to smallest sprockets (so the chain remains relatively straight)

 

[ColinJ]

On the middle ring of a triple the only adjustment is in the tension.

Not true for Campagnolo systems.

I have just stuck a triple on my Cannondale and the 10 speed Chorus left shifter and front mech which I had for the old double chainset work perfectly with the triple. I have multiple trimming clicks available to me on the middle ring to avoid chainrub across the whole range of the cassette.

 

[raleighnut]

Not true for Campagnolo systems.

I have just stuck a triple on my Cannondale and the 10 speed Chorus left shifter and front mech which I had for the old double chainset work perfectly with the triple. I have multiple trimming clicks available to me on the middle ring to avoid chainrub across the whole range of the cassette.

Not come across them, my Campagnolo equipped bike (Centaur 10 mechs and Centaur double crank) has Record bar-endshifters and a matching Record 10 cassette, but that has a centre stop for use with a triple.

 

[Hop3y]

Mine is a MTB by the way...

 

[raleighnut]

My initial reply was for a flat bar changing system with none of this trim gubbins fitted. I own 3 MTBs and a touring hybrid which have trigger shifter/brakes combined and on none can I access all gears quietly on the rear whilst in the middle ring, I can get the gear but have minor rub at the extremes.