Front Derailer Rubbing Noise

[mlugo]

Alex,
I have a Trek 7.5FX, with a triple up front and 9 cogs in the back. Typically when riding to work (20 miles round trip). I stay in the 2nd chain ring up front and use most of the nine cogs in the back.
It has been adjusted so that the higher gears are not rubbing but when I am going up a steep hill and have to go to a low gear (#3) it begins to rub. It also rubs in the highest gear, #9.
Should I expect to be able to use all 9 gears in the rear without having the front derailer rub when on the 2nd chain ring?
Is the front derailer not parallel to the bike frame?

[TESTUser111]

The outer cage of the front derailleur is generally set parallel to the largest front chainring. There should also be about 2mm clearance between the bottom of the front derailleur cage and the top of the largest chainring teeth. If it stills rubs, try playing with the front derailleur angle slightly one way or the other.
Maybe this video will help:
http://bikeride.com/adjust-front-derailer/