The stock 2 by 9 gives a nice touring /all around range between 23 and 90 gear inches with an 11-34 cassette and the dual drive offers 23 to 97 gear inches with a 42 tooth chainwheel... this is nearly the same gearing I have on my bikeE recumbent (Sachs 7 dual drive on a 20 inch wheel) while my folding touring bike has the same 2 by 9 derailleur set up with the 11-34.