Australian Cycling Forums - Bicycles Network Australia

I’ve found the crank arm is coming into contact with the derailer when the large front gear is selected so I’ve reduced the tension on the barrel adjuster and that seems to have cured it
Now I’m finding when I’m in the middle front gear, the chain rubs the front Detailer when using the 3 smallest rear cogs

Watch this (Park Tools FD setup) and redo the setup on your FD. Also check the cable to see if it is sticky/worn/damaged or a mounting bolt loose - there is usually a reason for a derailleur suddenly going bad like that.

https://www.youtube.com/watch?v=vcc5-ry4fA0

It isn't uncommon for the chain to rub on FD cage when in the smallest or largest front chainring and using the opposite extreme rear gear, but it is less common to happen on the middle front ring, and especially with 3 rear gears. Sounds like something have moved outwards on the FD pushing the cage outwards. Using the barrel adjuster may be OK as a temporary fix, but there is probably something else going on.

Also make sure the derailleur is parallel with the chain. Some derailleurs have a support screw to adjust it.

The high limit probably needs to be wound in a bit to prevent the derailleur swinging that far. When in the big ring and smallest rear sprocket, there should be no more than 1mm clearance between the chain and the outer plate of the derailleur. Reducing cable tension has let it drop away from the limit, but is then affecting your low and mid-range tune.

am50em wrote: Also make sure the derailleur is parallel with the chain. Some derailleurs have a support screw to adjust it.

Yes, ensure the derailleur is parallel with the rings, however only a comparitively few models have the support screw. What model derailleur are we talking?