Also riding fix gear. My first season of racing (in a distant millenium) the vets in my club told me to set my second bike up fix gear to learn to pedal smooth circles. It works really well (as long as you keep your gear low). Ride hills, both for the grunt workout going up and the ridiculous spin coming down. That spin is where you really learn. Until you have taught your leg muscles to completely relax, fast downhills are about as much fun as bronco riding on a jackhammer. But keep practicing. The day will come when you can pedal 40 downhill in a 42-17 (200 rpm). You will be pedaling perfect 100 rpm strokes on the flat. And you will have leg muscles that have learned to relax all the time they are not actually involve in the power portion of the stroke. Actually recovering while you pedal.

Now, don't get all dreamy about this - fix gear riding is hard work, on average 25-33% harder than the same ride with gears and often still not as fast. (Great in the winter. More benefit from shorter rides. Downhill are a lot warmer because you have to work.) Of course, there is the danger (?) that you will take to fix gear riding like some of us have. It can be addicting. And, set your fix gear up with good brakes. The point is to work on pedal style, not hipster showmanship. Braking with your legs to go downhill is exactly the wrong thing to be doing for your pedaling form. Spinning too fast to even think about braking with your legs is where you get the benefit. Get the good brakes so the EMS doesn't have to extract you from a tree.

Edit: Do you have only one bike? This might be a great time to find a local coop, buy a 1980s bike with horizontal dropouts and with their help, set it up as a fix gear. There are many suitable bikes out there. All the Japanese companies had models that work very well. Likewise Trek, the French bikes (but you may need the coop expertise there), many Raleigh s, etc. Bring your current bike along so you can purchase a bike you can set up with the same contact points (seat, handlebars and brake lever locations).

Ben (who's had and been riding at least one fix gear continuously since 1976)