IMHO the best way to radically increase cadence is to do various cadence-oriented workouts on bike trainer: it is just so much easier to follow the prompts and see your power output and cadence on the screen right in front of you without worrying about traffic. I know that for me it was *very* efficient and very noticeable improvements came fast - in less then a month. I know that on a trainer if workout asks me for something like 125 RPM at 125% FTP I can do it, it is just a matter of pedaling. Doing the same on the road will mean that I'll ride *real fast* and carefully monitoring cadence while still paying attention to the road will be IMHO much more difficult.