I have a road bike (optimo 4). Getting some issue with chain rubbing the front derailleur which I figured was partially due to derailleur alignment. However after I went to LBS and adjusted it I am still getting rubbing, although much less now. Would this be caused be a defect with the Crank chainring or something else? This only happens when set on the biggest ring in the front crank. The LBS said it was due to "soft metal" when pedaling hard. Trimming also helps but noise still there.
Crank is FSA Tempo. Should I buy a new crank e.g. 105 Shimano.