Just another thought... If the one-footed pedal drill I mentioned in my other post sounds boring / dangerous, etc... The other drill is to find a downhill grade. Pop it into a low gear -- i.e., the type of gear you'd use for climbing said hill. And then just pedal. There will be absolutely no resistance. If you're over-emphasizing the down-stroke portion of your pedal stroke, you'll bounce yourself all over the place. If you're really pedalling smoothly, you should be able to really wind up your cadence into the 150 range.