I've got a triple crank w/ 46-34-24 rings and an 8 speed 13-34 cassette in the rear. Went into my LBS w/ a bunch of low end Shimano front derailers and the guys said none of them would work w/ that crank. Any suggestions for a mid-price range FD that could handle those rings? I've got a Deore in the back. thanks!
SRAM X.7 and X.9 front derailleurs are rated for up to 48 rings and are Shimano compatable. However, most of the MTB derailleurs that you are looking at that are rated for 44 teeth will work ok with a 46 and a 12 tooth spread between rings. You may get a little more cross chaining rub if the cages are too narrow but you can always spread the cage out a little with a washer in the screw at the end of the cage.