if no one answered the question which I do not think they did, if you cannot pedal a fast cadence which many people cannot it is a good idea to do some cadence work to help this but chainrings.... You can get a double crankset and not have to change your shifter depending on what type of shifters you have. You would want a 53/39 in this case and the 12/25 should still be sufficient for hill climbing. You could also swap out your cassette with an 11-25, 11-26 which would give you that 11 to pedal with the 50 ring. Not sure what crankset you have but chainrings are probably around same price if not close to a used crankset...