Shimano front derailleurs and cage size?

[jockster]

I am having terrible chain rubbing when riding most of my gears, due to a too narrow chainline and are trying to find a workaround that would help me ride more gears without scraping.

Can I get a DA 7900 FD and add washers to the cage for increased clearance? What about using a 9sp front derailleur with 10sp shifters?

[eflayer]

what about a thin spacer between the bb shell and the bearing? that would move the crank further outward and maybe stop the rubbing?