i have recently bought a giant defy 2 with tiagra components, problem is when i'm pedalling (mainly on the big ring) the chain rubs outside of front derailleur at top of stroke and inside of front deraillleur at bottom of stroke.
would appreciate any suggestions about this, like i say bikes new and just put it through its first service and really thought it would come back noise free.
also fairly new to cycling so for all i know this could be normal
if just one chainring is bent then you can bend/hammer it back to shape. if the whole spider is off center then you can try rotating it in 90 degree increments if its a square taper crank. also check if the bottom bracket is loose