Originally Posted by
ThermionicScott
My vote would be to switch to an 11-28 cassette, find a double with 110BCD (old or new), and use 46/34 rings. You'll gain more low-end, the RD should be happy, the FD will be able to handle it after lowering it a little, and the top gear will be about the same.
The 5000 series Treks have a braze-on type front derailleur hanger that will maybe barely support lowering the FD enough for a 50 big ring. On my wife's 5200 I had to use a Dremel to grind the slot down enough so that the FD would work with a 49-39-28 triple.