The Trek 7.5fx has a triple crank, 48/36/26, and lists at $700. The 7.6fx had a double crank,50/36, and the bike lists at $1040. There are other differences between the bikes, as well, but obviously Trek feels that the double is an upgrade to the triple crank.
Can someone explain what's better about the double, what's gained and what's lost? Which is better for hills, the triple or the double? It's not just a weight thing, right?